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Cannibalism is the act of consuming another individual of the same species as food. Cannibalism is a common ecological interaction in the animal kingdom and has been recorded in more than 1,500 species.^[1] Human cannibalism is well documented, both in ancient and in recent times.^[2]

The rate of cannibalism increases in nutritionally poor environments as individuals turn to conspecifics as an additional food source.^[3] Cannibalism regulates population numbers, whereby resources such as food, shelter and territory become more readily available with the decrease of potential competition. Although it may benefit the individual, it has been shown that the presence of cannibalism decreases the expected survival rate of the whole population and increases the risk of consuming a relative.^[3] Other negative effects may include the increased risk of pathogen transmission as the encounter rate of hosts increases.^[4] Cannibalism, however, does not—as once believed—occur only as a result of extreme food shortage or of artificial/unnatural conditions, but may also occur under natural conditions in a variety of species.^[1]^[5]^[6]

Cannibalism is prevalent in aquatic ecosystems, in which up to approximately 90% of the organisms^[vague] engage in cannibalistic activity at some point in their life-cycle.^[vague]^[7] Cannibalism is not restricted to carnivorous species: it also occurs in herbivores and in detritivores.^[vague]^[5] Sexual cannibalism normally involves the consumption of the male by the female individual before, during or after copulation. ^[3] Other forms of cannibalism include size-structured cannibalism and intrauterine cannibalism.

Behavioural, physiological and morphological adaptations have evolved to decrease the rate of cannibalism in individual species.^[3]

Benefits

In environments where food availability is constrained, individuals can receive extra nutrition and energy if they use other conspecific individuals as an additional food source. This would, in turn, increase the survival rate of the cannibal and thus provide an evolutionary advantage in environments where food is scarce.^[8] A study conducted on wood frog tadpoles showed that those that exhibited cannibalistic tendencies had faster growth rates and higher fitness levels than non-cannibals.^[9] An increase of size and growth would give them the added benefit of protection from potential predators such as other cannibals and give them an advantage when competing for resources. ^[3]

The nutritional benefits of cannibalism may allow for the more efficient conversion of a conspecific diet into reusable resources than a fully herbaceous diet; as herbaceous diets may consist of excess elements which the animal has to expend energy to get rid of.^[10] This facilitates for faster development; however, a trade-off may occur as there may be less time to ingest these acquired resources. Studies have shown that there is a noticeable size difference between animals fed on a high conspecific diet which were smaller compared to those fed on a low conspecific diet.^[10] Hence, individual fitness could only be increased if the balance between developmental rate and size is balanced out, with studies showing that this is achieved in low conspecific diets.^[10]

Cannibalism regulates population numbers and benefits the cannibalistic individual and its kin as resources such as extra shelter, territory and food are freed; thereby increasing the fitness of the cannibal;^[8] by lowering crowding effects.^[11] However, this is only the case if the cannibal recognizes its own kin as this won't hinder any future chances of perpetuating its genes in future generations. The elimination of competition can also increase mating opportunities, allowing further spread of an individual's genes.

Costs

Animals which have diets consisting of predominantly conspecific prey expose themselves to a greater risk of injury and expend more energy foraging for suitable prey as compared to non-cannibalistic species.^[3]

In order to combat the risk of personal injury, a predator often targets younger or more vulnerable prey.^{[citation needed]} However, the time necessitated by such selective predation could result in a failure to meet the predator's self-set nutritional requirements.^[12] In addition, the consumption of conspecific prey may also involve the ingestion of defense compounds and hormones, which have the capacity to impact the developmental growth of the cannibal's offspring.^[10] Hence, predators normally partake in a cannibalistic diet in conditions where alternative food sources are absent or not as readily available.

Failure to recognize kin prey is also a disadvantage, provided cannibals target and consume younger individuals. For example, a male stickleback fish may often mistake their own "eggs" for their competitor's eggs, and hence would inadvertently eliminate some of its own genes from the available gene pool.^[3] Kin recognition has been observed in tadpoles of the spadefoot toad, whereby cannibalistic tadpoles of the same clutch tended to avoid consuming and harming siblings, while eating other non-siblings.^[13]

The act of cannibalism may also facilitate trophic disease transmission within a population, though cannibalistically spread pathogens and parasites generally employ alternative modes of infection.^[4]

Diseases transmitted through cannibalism

Cannibalism can potentially reduce the prevalence of parasites in the population by decreasing the number of susceptible hosts and indirectly killing the parasite in the host.^[14] It has been shown in some studies that the risk of encountering an infected victim increases when there is a higher cannibalism rate, though this risk drops as the number of available hosts decreases.^[14] However, this is only the case if the risk of disease transmission is low.^[4] Cannibalism is an ineffective method of disease spread as cannibalism in the animal kingdom is normally a one-on-one interaction, and the spread of disease requires group cannibalism; thereby it is rare for a disease to have evolved to rely solely on cannibalism to spread. Usually there are different means of transmission, such as with direct contact, maternal transmission, coprophagy, and necrophagy with different species.^[4] Infected individuals are more likely to be consumed than non-infected individuals, thus some research has suggested that the spread of disease may be a limiting factor to the prevalence of cannibalism in the population.^[14]

Some examples of diseases transmitted by cannibalism in mammals include Kuru which is a prion disease that degenerates the brain.^[4] This disease was prevalent in Papua New Guinea where tribes practiced endocannibalism in cannibalistic funeral rituals and consume the brains infected by these prions.^[15] It is a cerebellar dysfunctional disease which has symptoms including a broad-based gait and decreased motor activity control; however, the disease has a long incubation rate and symptoms may not appear until years later.^[15]

Bovine spongiform encephalopathy, or mad cow disease is another prion disease which is usually caused by feeding contaminated bovine tissue to other cattle.^[16] It is a neurodegenerative disease and could be spread to humans if the individual were to consume contaminated beef. The spread of parasites such as nematodes may also be facilitated by cannibalism as eggs from these parasites are transferred more easily from one host to another.^[4]

Other forms of diseases include sarcocystis and iridovirus in reptiles and amphibians; granulosus virus, chagas disease, and microsporidia in insects; stained prawn disease, white pot syndrome, helminthes and tapeworms in crustaceans and fish.^[4]

Foraging dynamics

Cannibalism may become apparent when direct competition for limited resources forces individuals to use other conspecific individuals as an additional resource to maintain their metabolic rates.^[3] Hunger drives individuals to increase their foraging rates, which in turn decreases their attack threshold and tolerance to other conspecific individuals. As resources dwindle, individuals are forced to change their behaviour which may lead to animal migration,^[17] confrontation, or cannibalism.^[3]

Cannibalism rates increase with increasing population density as it becomes more advantageous to prey on conspecific organisms than to forage in the environment.^[3] This is because the encounter rate between predator and prey increases, making cannibalism more convenient and beneficial than foraging within the environment. Over time, the dynamics within the population change as those with cannibalistic tendencies may receive additional nutritional benefits and increase the size ratio of predator to prey.^[18] The presence of smaller prey, or prey which are at a vulnerable stage of their life cycle, increases the chances of cannibalism occurring due to the reduced risk of injury.^[19] A feedback loop occurs when increasing rates of cannibalism decreases population densities, leading to an increased abundance of alternative food sources; making it more beneficial to forage within the environment than for cannibalism to occur.^[3] When population numbers and foraging rates increase, the carrying capacity for that resource in the area may be reached, thus forcing individuals to look for other resources such as conspecific prey.

Sexual cannibalism

Sexual cannibalism is present largely in spiders and other invertebrates, including gastropods.^[3] This refers to the killing and consumption of conspecific sexual partners during courtship, and during or after copulation. Normally, it is the female which consumes the conspecific male organism, though there have been some reported cases of the male consuming the adult female, however, this has only been recorded under laboratory conditions.^[3]^[20]^[21] Sexual cannibalism has been recorded in the female redback spider, black widow spider, praying mantis, and scorpion, among others.

In most species of spiders, the consumption of the male individual occurs before copulation and the male fails to transfer his sperm into the female.^[3] This may be due to mistaken identity such as in the case of the orb weaving spider which holds little tolerance to any spider which is present in its web and may mistake the vibrations for those of a prey item.^[3] Other reasons for male consumption before mating may include female choice and the nutritional advantages of cannibalism.^[22] The size of the male spider may play a part in determining its reproductive success as smaller males are less likely to be consumed during pre-copulation; however, larger males may be able to prevent the smaller ones from gaining access to the female.^[22] There exists a conflict of interest between males and females, as females may be more inclined to turn to cannibalism as a source of nutritional intake while the male's interest is mostly focused on ensuring paternity of the future generations.^[3] It was found that cannibalistic females produced offspring with greater survival rates than non-cannibalistic females, as cannibals produced greater clutches and larger egg sizes.^[23] Hence, species such as the male dark fishing spider of the family dolomedes self-sacrifice and spontaneously die during copulation to facilitate their own consumption by the female, thereby increasing the chance of survivorship of future offspring.^[24]

Sexual dimorphism has been theorised to have arisen from sexual selection as smaller males were captured more easily than larger males; however, it is also possible that sexual cannibalism only occurs due to the difference in size between male and females.^[3] Data comparing female and male spider body length shows that there is little support for the prior theory as there is not much correlation between body size and the presence of sexual cannibalism. Not all species of spiders which partake in sexual cannibalism exhibit size dimorphism.^[3]

The avoidance of sexual cannibalism is present in many male species to increase their rate of survival, whereby the male uses cautionary methods to lower the risk of his consumption.^[3] Male orb weaving spiders would often wait for females to moult or to finish eating before attempting to initiate mating, as the females are less likely to attack.^[3] Males which are vulnerable to post-copulation consumption may gather mating thread to generate a mechanical tension which they could use to spring away after insemination, while other spiders such as the crab spider may tangle the female's legs in webs to reduce the risk of the female capturing him.^[3] Male choice is common in mantids whereby males were observed to choose fatter females due to the reduced risk of attack and were more hesitant to approach starved females.^[25]

Size-structured cannibalism

Size-structured cannibalism is cannibalism in which older, larger, more mature individuals consume smaller, younger conspecifics. In size-structured populations, (where populations are made of individuals of various sizes, ages, and maturities), cannibalism can be responsible for 8% (Belding's ground squirrel) to 95% (dragonfly larvae) of the total mortality,^[1] making it a significant and important factor for population^[26] and community dynamics.^[27]

Size-structured cannibalism has commonly been observed in the wild for a variety of taxa. Vertebrate examples include chimpanzees, where groups of adult males have been observed to attack and consume infants.^[28]^[29]^[30]

Filial cannibalism

Filial cannibalism is a specific type of size-structured cannibalism in which adults eat their own offspring.^[31] Although most often thought of as parents eating live young, filial cannibalism includes parental consumption of stillborn infants and miscarried fetuses as well as infertile and still-incubating eggs. Vertebrate examples include pigs, where savaging accounts for a sizable percentage of total piglet deaths, and cats.^[32]

Filial cannibalism is particularly common in teleost fishes, appearing in at least seventeen different families of teleosts.^[33] Within this diverse group of fish, there have been many, variable explanations of the possible adaptive value of filial cannibalism. One of these is the energy-based hypothesis, which suggests that fish eat their offspring when they are low on energy as an investment in future reproductive success.^[31] This has been supported by experimental evidence, showing that male three-spined sticklebacks,^[31]^[34]^[35] male tessellated darters,^[36] and male sphinx blenny fish^[37] all consume or absorb their own eggs to maintain their physical conditions. In other words, when males of a fish species are low on energy, it might sometimes be beneficial for them to feed on their own offspring to survive and invest in future reproductive success.

Another hypothesis as to the adaptive value of filial cannibalism in teleosts is that it increases density-dependent egg survivorship. In other words, filial cannibalism simply increases overall reproductive success by helping the other eggs make it to maturity by thinning out the numbers. Possible explanations as to why this is so include increasing oxygen availability to the remaining eggs,^[38] the negative effects of accumulating embryo waste,^[39] and predation.^[39]

In some species of eusocial wasps, such as Polistes chinensis, the reproducing female will kill and feed younger larvae to her older brood. This occurs under food stressed conditions in order to ensure that the first generation of workers emerges without delay.^[40] Further evidence also suggests that occasionally filial cannibalism might be the unfortunate by-product of cuckoldry in fish. Males consume broods, which may include their own offspring, when they believe a certain percentage of the brood contains genetic material that is not theirs.^[34]^[41]

It is not always the parent that cannibalises the offspring, in some spiders mothers have been observed to feed themselves to their brood as the ultimate provision from mother to children, known as matriphagy. ^[42]

The dinosaur Coelophysis was once suspected to practice this form of cannibalism but this turned out to be wrong, although Deinonychus may have done. Skeletal remains from subadults with missing parts are suspected of having been eaten by other Deinonychus, mainly full-grown adults.

Infanticide

Infanticide is the killing of a non-adult animal by an adult of the same species. Infanticide is often, but not always, accompanied by cannibalism. It is often displayed in lions; a male lion encroaching on the territory of a rival pride will often kill any existing cubs fathered by other males; this brings the lionesses into heat more quickly, enabling the invading lion to sire his own young. This is a good example of cannibalistic behavior in a genetic context.

In many species of Lepidoptera, such as Cupido minimus and the Indian mealmoth, the first larvae to hatch will consume the other eggs or smaller larvae on the host plant, decreasing competition.^[43]^[44]

Intrauterine cannibalism

Intrauterine cannibalism is a behaviour in some carnivorous species, in which multiple embryos are created at impregnation, but only one or two are born. The larger or stronger ones consume their less-developed siblings as a source of nutrients.

In adelphophagy or embryophagy, the fetus eats sibling embryos, while in oophagy it feeds on eggs.^[45]^[46]

Adelphophagy occurs in some marine gastropods (calyptraeids, muricids, vermetids, and buccinids) and in some marine annelids (Boccardia proboscidia in Spionidae).^[47]

Intrauterine cannibalism is known to occur in lamnoid sharks^[48] such as the sand tiger shark, and in the fire salamander,^[49] as well as in some teleost fishes.^[46] The Carboniferous period chimaera, Delphyodontos dacriformes, is suspected of having practiced intrauterine cannibalism, also, due to the sharp teeth of the recently born (or possibly aborted) juveniles, and the presence of fecal matter in the juveniles' intestines.^[50]

Protection against cannibalism

Animals have evolved protection to prevent and deter potential predators such as those from their own kind.^[3] Many amphibian eggs are gelatinous and toxic to decrease edibility. Often, adults would lay their eggs in crevices, holes, or empty nesting sites to hide their eggs from potential conspecific predators which tend to ingest the eggs for an additional nutritional benefit or to get rid of genetic competition. In amphibians, the development of non-aquatic egg deposition has helped increase the survival rates of their young by the evolution of viviparity or direct development.^[3] In bees, worker policing occurs to prohibit worker reproduction, whereby workers cannibalize other worker laid eggs.^[51] Queen laid eggs have a different scent than worker laid eggs, allowing workers to differentiate between the two, allowing them to nurture and protect queen laid eggs rather than cannibalising them.^[51] Parental presence at nesting sites is also a common method of protection against infanticide committed by conspecific individuals, whereby the parent exhibits defensive displays to ward off potential predators. Parental investment in newborns are generally higher during their early stages of development whereby behaviours such as aggression, territorial behaviour, and pregnancy blocking become more apparent.^[3]

Morphological plasticity helps an individual account for different predation stresses, thereby increasing individual survival rates.^[52] Japanese brown frog tadpoles have been shown to exhibit morphological plasticity when they are in a high stress environment where cannibalism between tadpoles and more developed individuals were present. Shifting their morphology plays a key role in their survival, creating bulkier bodies when put into environments where more developed tadpoles were present, to make it difficult for the individuals to swallow them whole.^[52] Diet shifts between different stages of development have also evolved to decrease competition between each stage, thereby increasing the amount of food availability so that there is a decreased chance that the individuals will turn to cannibalism as an additional food source.^[3]

References

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^ Stebbins, Robert C.; Nathan W. Cohen (1995). A Natural History of Amphibians. Princeton, NJ: Princeton University Press. p. 9. ISBN 978-0-691-10251-1.
^ Lund, R. (1980). "Viviparity and intrauterine feeding in a new holocephalan fish from the Lower Carboniferous of Montana". Science. 209 (4457): 697–699. Bibcode:1980Sci...209..697L. doi:10.1126/science.209.4457.697. PMID 17821193.
^ ^a ^b Santomauro, G.; Oldham, N. J.; Boland, W.; Engels, W. (2004). "Cannibalism of diploid drone larvae in the honey bee (Apis mellifera) is released by odd pattern of cuticular substances". Journal of Apicultural Research. 43 (2): 69–74. doi:10.1080/00218839.2004.11101114. {{cite journal}}: Unknown parameter |lastauthoramp= ignored (|name-list-style= suggested) (help)
^ ^a ^b Kishida, O.; Trussell, G. C.; Nishimura, K.; Ohgushi, T. (2009). "Inducible Defenses in Prey Intensify Predator Cannibalism". Ecology. 90 (11): 3150–3158. doi:10.1890/08-2158.1. hdl:2115/44963. PMID 19967870. {{cite journal}}: Unknown parameter |lastauthoramp= ignored (|name-list-style= suggested) (help)

@@ Line 3: / Line 3: @@
 [[File:A lusitanicus cannibalizing.jpg|thumb|A slug ''[[Arion vulgaris]]'' eating another individual of the same species]]
-'''Cannibalism''' is the act of consuming another individual of the same species as [[food]]. Cannibalism is a common [[ecology|ecological]] interaction in the animal kingdom and has been recorded in more than 1,500 [[species]].<ref name="PolisThe">G. A. Polis, The evolution and dynamics of intraspecific predation, ''Annual Review of Ecology and Systematics'' 12, 225-251 (1981)</ref> [[Human cannibalism]] is well documented, both in ancient and in recent times.<ref>{{cite book |editor-last= Goldman |editor-first= Laurence |year= 1999 |title= The Anthropology of Cannibalism |publisher= Greenwood Publishing Group |isbn= 978-0-89789-596-5}}</ref>
+'''Cannibalism''' is the act of consuming another individual of the same species as [[food]]. Cannibalism is a common [[ecology|ecological]] interaction in the animal kingdom and has been recorded in more than 1,500 [[species]].<ref name="PolisThe">{{cite journal|doi=10.1146/annurev.es.12.110181.001301|title=The Evolution and Dynamics of Intraspecific Predation|year=1981|last1=Polis|first1=G. A.|journal=Annual Review of Ecology and Systematics|volume=12|pages=225–251}}</ref> [[Human cannibalism]] is well documented, both in ancient and in recent times.<ref>{{cite book |editor-last= Goldman |editor-first= Laurence |year= 1999 |title= The Anthropology of Cannibalism |publisher= Greenwood Publishing Group |isbn= 978-0-89789-596-5}}</ref>
-The rate of cannibalism increases in nutritionally poor environments as individuals turn to conspecifics as an additional food source.<ref name= "Elgar">Elgar, M.A. & Crespi, B.J. 1992, Cannibalism: ecology and evolution among diverse taxa, Oxford University Press, Oxford [England]; New York.</ref> Cannibalism regulates population numbers, whereby resources such as food, shelter and territory become more readily available with the decrease of potential competition. Although it may benefit the individual, it has been shown that the presence of cannibalism decreases the expected survival rate of the whole population and increases the risk of consuming a relative.<ref name= "Elgar"/> Other negative effects may include the increased risk of [[pathogen]] transmission as the encounter rate of hosts increases.<ref name= "Rudolf">Rudolf, V.H.W. & Antonovics, J. 2007, "Disease transmission by cannibalism: rare event or common occurrence?", Proceedings of the Royal Society B: Biological Sciences, vol. 274, no. 1614, pp. 1205-1210.</ref> Cannibalism, however, does not—as once believed—occur only as a result of extreme food shortage or of artificial/unnatural conditions, but may also occur under natural conditions in a variety of species.<ref name="PolisThe" /><ref name="Laurel R. Fox 1975">Laurel R. Fox, "Cannibalism in natural populations", ''Annual Review of Ecology and Systematics'' 6, 87-106 (1975)</ref><ref>M. A. Elgar and [[Bernard Crespi|B. J. Crespi]] (eds), ''Cannibalism: Ecology and evolution among diverse taxa''. (Oxford University Press, New York, 1992)</ref>
+The rate of cannibalism increases in nutritionally poor environments as individuals turn to conspecifics as an additional food source.<ref name= "Elgar">Elgar, M.A. & Crespi, B.J. (1992) ''Cannibalism: ecology and evolution among diverse taxa'', Oxford University Press, Oxford [England]; New York.</ref> Cannibalism regulates population numbers, whereby resources such as food, shelter and territory become more readily available with the decrease of potential competition. Although it may benefit the individual, it has been shown that the presence of cannibalism decreases the expected survival rate of the whole population and increases the risk of consuming a relative.<ref name= "Elgar"/> Other negative effects may include the increased risk of [[pathogen]] transmission as the encounter rate of hosts increases.<ref name= "Rudolf">{{cite journal|pmid=17327205|year=2007|last1=Rudolf|first1=V. H.|last2=Antonovics|first2=J.|title=Disease transmission by cannibalism: Rare event or common occurrence?|journal=Proceedings. Biological Sciences|volume=274|issue=1614|pages=1205–10|doi=10.1098/rspb.2006.0449|pmc=2189571}}</ref> Cannibalism, however, does not—as once believed—occur only as a result of extreme food shortage or of artificial/unnatural conditions, but may also occur under natural conditions in a variety of species.<ref name="PolisThe" /><ref name="Laurel R. Fox 1975">{{cite journal|doi=10.1146/annurev.es.06.110175.000511|title=Cannibalism in Natural Populations|year=1975|last1=Fox|first1=L. R.|journal=Annual Review of Ecology and Systematics|volume=6|pages=87–106}}</ref><ref>Elgar, M. A. and [[Bernard Crespi|Crespi, B. J.]] (eds) (1992) ''Cannibalism: Ecology and evolution among diverse taxa''. Oxford University Press, New York.</ref>
 Cannibalism is prevalent in [[aquatic ecosystem]]s, in which up to approximately 90% of the [[organism]]s{{vague|Reason= Is this intended to reflect counts of cann'istic individuals, of species w/ any cannibals, or approx limit w/in any species. And why no distinction between predation and scavenging?|date= May 2018}} engage in cannibalistic activity at some point in their [[biological life cycle|life-cycle]].{{vague|Reason=  Is silence about plant & protozoan species merely neglectful, or intentional inclusion?|date =May 2018}}<ref>{{cite book | last1 = Rudolf | first1 = Volker H. W. | title = The Influence of Cannibalism and Size Structure on the Dynamics of Aquatic Communities | url =  https://books.google.com/books?id=SpAoAAAAYAAJ | publisher = University of Virginia | date = 2007 | page = 2 | access-date = 23 Feb 2019 | quote = Cannibalism is a common ecological interaction in the animal kingdom, and it is ubiquitous in aquatic and terrestrial food webs [...].}}</ref> Cannibalism is not restricted to [[carnivorous]] species: it also occurs in [[herbivore]]s and in [[detritivore]]s.{{vague|which interpretation of the silence about the vegetable kingdom is intended?|date= May 2018}}<ref name="Laurel R. Fox 1975"/> [[Sexual cannibalism]] normally involves the consumption of the male by the female individual before, during or after copulation. <ref name= "Elgar"/> Other forms of cannibalism include size-structured cannibalism and [[intrauterine cannibalism]].
@@ Line 12: / Line 12: @@
 == Benefits ==
-In environments where food availability is constrained, individuals can receive extra nutrition and energy if they use other conspecific individuals as an additional food source. This would, in turn, increase the survival rate of the cannibal and thus provide an evolutionary advantage in environments where food is scarce.<ref name="Snyder">Snyder, W.E., Joseph, S.B., Preziosi, R.F. & Moore, A.J. 2000, "Nutritional Benefits of Cannibalism for the Lady BeetleHarmonia axyridis(Coleoptera: Coccinellidae) When Prey Quality is Poor", Environmental Entomology, vol. 29, no. 6, pp. 1173-1179.</ref> A study conducted on [[wood frog]] tadpoles showed that those that exhibited cannibalistic tendencies had faster growth rates and higher fitness levels than non-cannibals.<ref>Jefferson, D.M., Hobson, K.A., Demuth, B.S., Ferrari, M.C.O. & Chivers, D.P. 2014, "Frugal cannibals: how consuming conspecific tissues can provide conditional benefits to wood frog tadpoles (Lithobates sylvaticus)", Naturwissenschaften, vol. 101, no. 4, pp. 291-303.</ref> An increase of size and growth would give them the added benefit of protection from potential predators such as other cannibals and give them an advantage when competing for resources. <ref name= "Elgar"/>
+In environments where food availability is constrained, individuals can receive extra nutrition and energy if they use other conspecific individuals as an additional food source. This would, in turn, increase the survival rate of the cannibal and thus provide an evolutionary advantage in environments where food is scarce.<ref name="Snyder">
+{{cite journal|author=Snyder, W.E., Joseph, S.B., Preziosi, R.F. & Moore, A.J. |title=Nutritional Benefits of Cannibalism for the Lady Beetle ''Harmonia axyridis'' (Coleoptera: Coccinellidae) When Prey Quality is Poor|journal=Environmental Entomology|volume=29|issue=6|pages=1173–1179|doi=10.1603/0046-225X-29.6.1173|year=2000}}</ref> A study conducted on [[wood frog]] tadpoles showed that those that exhibited cannibalistic tendencies had faster growth rates and higher fitness levels than non-cannibals.<ref>
+{{cite journal|author=Jefferson, D.M., Hobson, K.A., Demuth, B.S., Ferrari, M.C.O. & Chivers, D.P.|title=Frugal cannibals: how consuming conspecific tissues can provide conditional benefits to wood frog tadpoles (''Lithobates sylvaticus'')|journal=Die Naturwissenschaften|volume=101|issue=4|pages=291–303|pmid=24535171|year=2014|doi=10.1007/s00114-014-1156-4|bibcode=2014NW....101..291J}}</ref> An increase of size and growth would give them the added benefit of protection from potential predators such as other cannibals and give them an advantage when competing for resources. <ref name= "Elgar"/>
-The nutritional benefits of cannibalism may allow for the more efficient conversion of a conspecific diet into reusable resources than a fully herbaceous diet; as herbaceous diets may consist of excess elements which the animal has to expend energy to get rid of.<ref name= "Simpson">.  Simpson, J., Joncour, B. & Nelson, W.A. 2018, "Low levels of cannibalism increase fitness in an herbaceous tortrix moth", Behavioral Ecology and
+The nutritional benefits of cannibalism may allow for the more efficient conversion of a conspecific diet into reusable resources than a fully herbaceous diet; as herbaceous diets may consist of excess elements which the animal has to expend energy to get rid of.<ref name= "Simpson">{{cite journal|doi=10.1007/s00265-018-2439-0|title=Low levels of cannibalism increase fitness in an herbaceous tortrix moth|year=2018|last1=Simpson|first1=Jenna|last2=Joncour|first2=Barbara|last3=Nelson|first3=William Andrew|journal=Behavioral Ecology and Sociobiology|volume=72|issue=2}}
-Sociobiology, vol. 72, no. 2, pp.
--11.
 </ref> This facilitates for faster development; however, a trade-off may occur as there may be less time to ingest these acquired resources. Studies have shown that there is a noticeable size difference between animals fed on a high conspecific diet which were smaller compared to those fed on a low conspecific diet.<ref name= "Simpson"/>  Hence, individual fitness could only be increased if the balance between developmental rate and size is balanced out, with studies showing that this is achieved in low conspecific diets.<ref name= "Simpson"/>
-Cannibalism regulates population numbers and benefits the cannibalistic individual and its kin as resources such as extra shelter, territory and food are freed; thereby increasing the fitness of the cannibal;<ref name="Snyder" /> by lowering crowding effects.<ref>Nishimura, K. & Isoda, Y. 2004, "Evolution of cannibalism: referring to costs of cannibalism", Journal of Theoretical Biology, vol. 226, no. 3, pp. 293-302.</ref> However, this is only the case if the cannibal recognizes its own kin as this won't hinder any future chances of perpetuating its genes in future generations. The elimination of competition can also increase mating opportunities, allowing further spread of an individual's genes.
+Cannibalism regulates population numbers and benefits the cannibalistic individual and its kin as resources such as extra shelter, territory and food are freed; thereby increasing the fitness of the cannibal;<ref name="Snyder" /> by lowering crowding effects.<ref>{{cite journal|pmid=14643643|year=2004|last1=Nishimura|first1=K.|last2=Isoda|first2=Y.|title=Evolution of cannibalism: Referring to costs of cannibalism|journal=Journal of Theoretical Biology|volume=226|issue=3|pages=293–302|doi=10.1016/j.jtbi.2003.09.007}}</ref> However, this is only the case if the cannibal recognizes its own kin as this won't hinder any future chances of perpetuating its genes in future generations. The elimination of competition can also increase mating opportunities, allowing further spread of an individual's genes.
 ==Costs==
 Animals which have diets consisting of predominantly conspecific prey  expose themselves to a greater risk of injury and expend more energy foraging for suitable prey as compared to non-cannibalistic species.<ref name= "Elgar"/>
-In order to combat the risk of personal injury, a predator often targets younger or more vulnerable prey.{{citation needed|date=October 2018}} However, the time necessitated by such selective predation could result in a failure to meet the predator's self-set [[nutritional requirement]]s.<ref> Chapman, J.W. 1999, "Fitness consequences of cannibalism in [[Spodoptera frugiperda]] (fall armyworm), Behavioral Ecology, vol. 10, no. 3, pp. 298-303.</ref> In addition, the consumption of conspecific prey may also involve the ingestion of defense compounds and [[hormone]]s, which have the capacity to  impact the developmental growth of the cannibal's offspring.<ref name= "Simpson"/> Hence, predators normally partake in a cannibalistic diet in conditions where alternative food sources are absent or not as readily available.
+In order to combat the risk of personal injury, a predator often targets younger or more vulnerable prey.{{citation needed|date=October 2018}} However, the time necessitated by such selective predation could result in a failure to meet the predator's self-set [[nutritional requirement]]s.<ref>
+{{cite document|author= Chapman, J.W. |title=Fitness consequences of cannibalism in ''Spodoptera frugiperda'' (fall armyworm)|doi=10.1093/beheco/10.3.298}}</ref> In addition, the consumption of conspecific prey may also involve the ingestion of defense compounds and [[hormone]]s, which have the capacity to  impact the developmental growth of the cannibal's offspring.<ref name= "Simpson"/> Hence, predators normally partake in a cannibalistic diet in conditions where alternative food sources are absent or not as readily available.
-Failure to recognize kin prey is also a disadvantage, provided cannibals target and consume younger individuals. For example, a male [[stickleback]] fish may often mistake their own "eggs" for their competitor's eggs, and hence would inadvertently eliminate some of its own genes from the available [[gene pool]].<ref name= "Elgar"/> Kin recognition has been observed in [[tadpole]]s of the spadefoot toad, whereby cannibalistic tadpoles of the same clutch tended to avoid consuming and harming siblings, while eating other non-siblings.<ref name= "Pfennig">. Pfennig, D.W., Reeve, H.K. & Sherman, P.W. 1993, "Kin recognition and cannibalism in spadefoot toad tadpoles", Animal Behaviour, vol. 46, no. 1, pp. 87-94.
+Failure to recognize kin prey is also a disadvantage, provided cannibals target and consume younger individuals. For example, a male [[stickleback]] fish may often mistake their own "eggs" for their competitor's eggs, and hence would inadvertently eliminate some of its own genes from the available [[gene pool]].<ref name= "Elgar"/> Kin recognition has been observed in [[tadpole]]s of the spadefoot toad, whereby cannibalistic tadpoles of the same clutch tended to avoid consuming and harming siblings, while eating other non-siblings.<ref name= "Pfennig">{{cite journal|doi=10.1006/anbe.1993.1164|title=Kin recognition and cannibalism in spadefoot toad tadpoles|year=1993|last1=Pfennig|first1=David W.|last2=Reeve|first2=Hudson K.|last3=Sherman|first3=Paul W.|journal=Animal Behaviour|volume=46|pages=87–94}}</ref>
-</ref>
 The act of cannibalism may also facilitate trophic disease transmission within a population, though cannibalistically spread pathogens and parasites generally employ alternative modes of infection.<ref name= "Rudolf"/>
@@ Line 33: / Line 33: @@
 == Diseases transmitted through cannibalism ==
-Cannibalism can potentially reduce the prevalence of [[Parasitism|parasites]] in the population by decreasing the number of susceptible hosts and indirectly killing the parasite in the host.<ref name= "Benjamin">. Benjamin G Van Allen, Dillemuth, F.P., Flick, A.J., Faldyn, M.J., Clark, D.R., Volker H W Rudolf & Elderd, B.D. 2017, "Cannibalism and Infectious Disease: Friends or Foes?", The American Naturalist, vol. 190, no. 3, pp. 299-312.</ref> It has been shown in some studies that the risk of encountering an infected victim increases when there is a higher cannibalism rate, though this risk drops as the number of available hosts decreases.<ref name= "Benjamin"/> However, this is only the case if the risk of disease transmission is low.<ref name= "Rudolf"/> Cannibalism is an ineffective method of disease spread as cannibalism in the animal kingdom is normally a one-on-one interaction, and the spread of disease requires group cannibalism; thereby it is rare for a disease to have evolved to rely solely on cannibalism to spread. Usually there are different means of transmission, such as with direct contact, maternal transmission, [[Coprophagia|coprophagy]], and [[Scavenger|necrophagy]] with different species.<ref name= "Rudolf"/> Infected individuals are more likely to be consumed than non-infected individuals, thus some research has suggested that the spread of disease may be a limiting factor to the prevalence of cannibalism in the population.<ref name= "Benjamin"/>
+Cannibalism can potentially reduce the prevalence of [[Parasitism|parasites]] in the population by decreasing the number of susceptible hosts and indirectly killing the parasite in the host.<ref name= "Benjamin">{{cite journal|pmid=28829639|year=2017|last1=Van Allen|first1=B. G.|last2=Dillemuth|first2=F. P.|last3=Flick|first3=A. J.|last4=Faldyn|first4=M. J.|last5=Clark|first5=D. R.|author6=Rudolf VHW|last7=Elderd|first7=B. D.|title=Cannibalism and Infectious Disease: Friends or Foes?|journal=The American Naturalist|volume=190|issue=3|pages=299–312|doi=10.1086/692734|hdl=1911/97826}}</ref> It has been shown in some studies that the risk of encountering an infected victim increases when there is a higher cannibalism rate, though this risk drops as the number of available hosts decreases.<ref name= "Benjamin"/> However, this is only the case if the risk of disease transmission is low.<ref name= "Rudolf"/> Cannibalism is an ineffective method of disease spread as cannibalism in the animal kingdom is normally a one-on-one interaction, and the spread of disease requires group cannibalism; thereby it is rare for a disease to have evolved to rely solely on cannibalism to spread. Usually there are different means of transmission, such as with direct contact, maternal transmission, [[Coprophagia|coprophagy]], and [[Scavenger|necrophagy]] with different species.<ref name= "Rudolf"/> Infected individuals are more likely to be consumed than non-infected individuals, thus some research has suggested that the spread of disease may be a limiting factor to the prevalence of cannibalism in the population.<ref name= "Benjamin"/>
-Some examples of diseases transmitted by cannibalism in mammals include [[Kuru (disease)|Kuru]] which is a [[prion]] disease that degenerates the brain.<ref name= "Rudolf"/> This disease was prevalent in [[Papua New Guinea]] where tribes practiced [[endocannibalism]] in cannibalistic funeral rituals and consume the brains infected by these prions.<ref name= "Prusiner">. Prusiner, S.B. 2008, "Reflections on Kuru", Philosophical Transactions: Biological Sciences, vol. 363, no. 1510, pp. 3654-3656.</ref> It is a [[Cerebellum|cerebellar]] dysfunctional disease which has symptoms including a broad-based [[gait]] and decreased motor activity control; however, the disease has a long incubation rate and symptoms may not appear until years later.<ref name= "Prusiner"/>
+Some examples of diseases transmitted by cannibalism in mammals include [[Kuru (disease)|Kuru]] which is a [[prion]] disease that degenerates the brain.<ref name= "Rudolf"/> This disease was prevalent in [[Papua New Guinea]] where tribes practiced [[endocannibalism]] in cannibalistic funeral rituals and consume the brains infected by these prions.<ref name= "Prusiner">{{cite journal|pmc=2735541|doi=10.1098/rstb.2008.4024|title=Reflections on kuru|year=2008|last1=Prusiner|first1=Stanley B.|journal=Philosophical Transactions of the Royal Society B: Biological Sciences|volume=363|issue=1510|pages=3654–3656}}</ref> It is a [[Cerebellum|cerebellar]] dysfunctional disease which has symptoms including a broad-based [[gait]] and decreased motor activity control; however, the disease has a long incubation rate and symptoms may not appear until years later.<ref name= "Prusiner"/>
-[[Bovine spongiform encephalopathy]], or mad cow disease is another prion disease which is usually caused by feeding contaminated bovine tissue to other cattle.<ref name= "Finberg">. Finberg, K.E. 2004, "Mad cow disease in the United States: an update on bovine spongiform encephalopathy and variant Creutzfeldt-Jakob disease", Clinical
+[[Bovine spongiform encephalopathy]], or mad cow disease is another prion disease which is usually caused by feeding contaminated bovine tissue to other cattle.<ref name= "Finberg">{{cite journal|doi=10.1016/j.clinmicnews.2004.07.001|title=Mad cow disease in the United States: An update on bovine spongiform encephalopathy and variant Creutzfeldt-Jakob disease|year=2004|last1=Finberg|first1=Karin E.|journal=Clinical Microbiology Newsletter|volume=26|issue=15|pages=113–118}}
-Microbiology Newsletter, vol. 26,
-no. 15, pp. 113-118.
 </ref> It is a [[neurodegeneration|neurodegenerative]] disease and could be spread to humans if the individual were to consume contaminated beef. The spread of parasites such as [[nematode]]s may also be facilitated by cannibalism as eggs from these parasites are transferred more easily from one host to another.<ref name= "Rudolf"/>
@@ Line 45: / Line 43: @@
 == Foraging dynamics ==
-Cannibalism may become apparent when direct competition for limited resources forces individuals to use other conspecific individuals as an additional resource to maintain their metabolic rates.<ref name= "Elgar"/> Hunger drives individuals to increase their foraging rates, which in turn decreases their attack threshold and tolerance to other conspecific individuals. As resources dwindle, individuals are forced to change their behaviour which may lead to [[animal migration]],<ref>Milner-Gulland, E.J., Fryxell, J.M. & Sinclair, A.R.E. 2011, Animal migration: a synthesis, Oxford University Press, Oxford.</ref> confrontation, or cannibalism.<ref name= "Elgar"/>
+Cannibalism may become apparent when direct competition for limited resources forces individuals to use other conspecific individuals as an additional resource to maintain their metabolic rates.<ref name= "Elgar"/> Hunger drives individuals to increase their foraging rates, which in turn decreases their attack threshold and tolerance to other conspecific individuals. As resources dwindle, individuals are forced to change their behaviour which may lead to [[animal migration]],<ref>Milner-Gulland, E.J., Fryxell, J.M. & Sinclair, A.R.E. (2011) ''Animal migration: a synthesis'', Oxford University Press, Oxford.</ref> confrontation, or cannibalism.<ref name= "Elgar"/>
-Cannibalism rates increase with increasing population density as it becomes more advantageous to prey on conspecific organisms than to forage in the environment.<ref name= "Elgar"/> This is because the encounter rate between predator and prey increases, making cannibalism more convenient and beneficial than foraging within the environment. Over time, the dynamics within the population change as those with cannibalistic tendencies may receive additional nutritional benefits and increase the size ratio of predator to prey.<ref>Brose, U., Ehnes, R.B., Rall, B.C., Vucic-Pestic, O., Berlow, E.L. & Scheu, S. 2008, "Foraging Theory Predicts Predator-Prey Energy Fluxes", Journal of Animal Ecology, vol. 77, no. 5, pp. 1072-1078.</ref> The presence of smaller prey, or prey which are at a vulnerable stage of their life cycle, increases the chances of cannibalism occurring due to the reduced risk of injury.<ref>Daly, B. & Long, W.C. 2014, "Inter-cohort cannibalism of early benthic phase blue king crabs (Paralithodes platypus): alternate foraging strategies in different habitats lead to different functional responses", PLOS One, vol. 9, no. 2, pp. e88694.</ref> A feedback loop occurs when increasing rates of cannibalism decreases population densities, leading to an increased abundance of alternative food sources; making it more beneficial to forage within the environment than for cannibalism to occur.<ref name= "Elgar"/> When population numbers and foraging rates increase, the carrying capacity for that resource in the area may be reached, thus forcing individuals to look for other resources such as conspecific prey.
+Cannibalism rates increase with increasing population density as it becomes more advantageous to prey on conspecific organisms than to forage in the environment.<ref name= "Elgar"/> This is because the encounter rate between predator and prey increases, making cannibalism more convenient and beneficial than foraging within the environment. Over time, the dynamics within the population change as those with cannibalistic tendencies may receive additional nutritional benefits and increase the size ratio of predator to prey.<ref>{{cite journal|doi=10.1111/j.1365-2656.2008.01408.x |pmid=18540967 |title=Foraging theory predicts predator-prey energy fluxes |year=2008 |last1=Brose |first1=U. |last2=Ehnes |first2=R. B. |last3=Rall |first3=B. C. |last4=Vucic-Pestic |first4=O. |last5=Berlow |first5=E. L. |last6=Scheu |first6=S. |journal=Journal of Animal Ecology |volume=77 |issue=5 |pages=1072–1078 }}</ref> The presence of smaller prey, or prey which are at a vulnerable stage of their life cycle, increases the chances of cannibalism occurring due to the reduced risk of injury.<ref>
+{{cite journal|author=Daly, B. & Long, W.C. |title=Inter-cohort cannibalism of early benthic phase blue king crabs (''Paralithodes platypus''): alternate foraging strategies in different habitats lead to different functional responses|journal=PLOS ONE|volume=9|issue=2|pages=e88694|doi=10.1371/journal.pone.0088694|pmid=24558414|bibcode=2014PLoSO...988694D|year=2014}}</ref> A feedback loop occurs when increasing rates of cannibalism decreases population densities, leading to an increased abundance of alternative food sources; making it more beneficial to forage within the environment than for cannibalism to occur.<ref name= "Elgar"/> When population numbers and foraging rates increase, the carrying capacity for that resource in the area may be reached, thus forcing individuals to look for other resources such as conspecific prey.
 == Sexual cannibalism ==
 {{main|Sexual cannibalism}}
-Sexual cannibalism is present largely in spiders and other [[invertebrate]]s, including [[Gastropoda|gastropods]].<ref name= "Elgar"/> This refers to the killing and consumption of [[Conspecificity|conspecific]] sexual partners during courtship, and during or after copulation. Normally, it is the female which consumes the conspecific male organism, though there have been some reported cases of the male consuming the adult female, however, this has only been recorded under laboratory conditions.<ref name= "Elgar"/><ref name="esc">{{cite web |url=http://ib.berkeley.edu/courses/ib160/past_papers/suttle.html |title=The Evolution of Sexual Cannibalism |author=Kenwyn Blake Suttle |year=1999 |publisher=[[University of California, Berkeley]]}}</ref><ref name="isopod">{{cite journal |url=http://www.bioone.org/perlserv/?request=get-abstract&issn=0278-0372&volume=023&issue=03&page=0662 |title=Cannibalism within mating pairs of the parasitic isopod ''Ichthyoxenus fushanensis'' |author=Min-Li Tsai & Chang-Feng Dai |journal=[[Journal of Crustacean Biology]] |volume=23 |issue=3 |year=2003 |pages=662–668 |doi=10.1651/C-2343 |format=abstract page}}</ref> Sexual cannibalism has been recorded in the female [[redback spider]], [[latrodectus|black widow spider]], [[Mantis|praying mantis]], and [[scorpion]], among others.
+Sexual cannibalism is present largely in spiders and other [[invertebrate]]s, including [[Gastropoda|gastropods]].<ref name= "Elgar"/> This refers to the killing and consumption of [[Conspecificity|conspecific]] sexual partners during courtship, and during or after copulation. Normally, it is the female which consumes the conspecific male organism, though there have been some reported cases of the male consuming the adult female, however, this has only been recorded under laboratory conditions.<ref name= "Elgar"/><ref name="esc">{{cite web |url=http://ib.berkeley.edu/courses/ib160/past_papers/suttle.html |title=The Evolution of Sexual Cannibalism |author=Kenwyn Blake Suttle |year=1999 |publisher=[[University of California, Berkeley]]}}</ref><ref name="isopod">{{cite journal |title=Cannibalism within mating pairs of the parasitic isopod ''Ichthyoxenus fushanensis'' |author=Min-Li Tsai & Chang-Feng Dai |journal=[[Journal of Crustacean Biology]] |volume=23 |issue=3 |year=2003 |pages=662–668 |doi=10.1651/C-2343 }}</ref> Sexual cannibalism has been recorded in the female [[redback spider]], [[latrodectus|black widow spider]], [[Mantis|praying mantis]], and [[scorpion]], among others.
-In most species of spiders, the consumption of the male individual occurs before [[Sexual intercourse|copulation]] and the male fails to transfer his sperm into the female.<ref name= "Elgar"/> This may be due to mistaken identity such as in the case of the [[Orb-weaver spider|orb weaving spider]] which holds little tolerance to any spider which is present in its web and may mistake the vibrations for those of a prey item.<ref name= "Elgar"/> Other reasons for male consumption before mating may include female choice and the nutritional advantages of cannibalism.<ref name= "ElgarF">Elgar, M.A. & Fahey, B.F. 1996, "Sexual cannibalism, competition, and size dimorphism in the orb-weaving spider Nephila plumipes Latreille (Araneae: Araneoidea)", Behavioral
+In most species of spiders, the consumption of the male individual occurs before [[Sexual intercourse|copulation]] and the male fails to transfer his sperm into the female.<ref name= "Elgar"/> This may be due to mistaken identity such as in the case of the [[Orb-weaver spider|orb weaving spider]] which holds little tolerance to any spider which is present in its web and may mistake the vibrations for those of a prey item.<ref name= "Elgar"/> Other reasons for male consumption before mating may include female choice and the nutritional advantages of cannibalism.<ref name= "ElgarF">
+{{cite journal|author=Elgar, M.A. & Fahey, B.F. |title=Sexual cannibalism, competition, and size dimorphism in the orb-weaving spider ''Nephila plumipes'' Latreille (Araneae: Araneoidea)|journal=Behavioral Ecology|volume=7|issue=2|pages=195–198|doi=10.1093/beheco/7.2.195|year=1996}}</ref> The size of the male spider may play a part in determining its reproductive success as smaller males are less likely to be consumed during pre-copulation; however, larger males may be able to prevent the smaller ones from gaining access to the female.<ref name= "ElgarF"/>
-Ecology, vol. 7, no. 2, pp.
+There exists a conflict of interest between males and females, as females may be more inclined to turn to cannibalism as a source of nutritional intake while the male's interest is mostly focused on ensuring paternity of the future generations.<ref name= "Elgar"/> It was found that cannibalistic females produced offspring with greater survival rates than non-cannibalistic females, as cannibals produced greater [[Clutch (eggs)|clutches]] and larger egg sizes.<ref>{{cite journal|doi=10.1016/j.anbehav.2011.10.027|title=Sexual cannibalism benefits offspring survival|year=2012|last1=Welke|first1=Klaas W.|last2=Schneider|first2=Jutta M.|journal=Animal Behaviour|volume=83|pages=201–207}}</ref> Hence, species such as the male [[Dolomedes tenebrosus|dark fishing spider]] of the family [[dolomedes]] self-sacrifice and spontaneously die during copulation to facilitate their own consumption by the female, thereby increasing the chance of survivorship of future offspring.<ref>{{cite journal|doi=10.1016/j.cub.2016.08.010|pmid=27720621|title=Males Can Benefit from Sexual Cannibalism Facilitated by Self-Sacrifice|year=2016|last1=Schwartz|first1=Steven K.|last2=Wagner|first2=William E.|last3=Hebets|first3=Eileen A.|journal=Current Biology|volume=26|issue=20|pages=2794–2799}}
--198.</ref> The size of the male spider may play a part in determining its reproductive success as smaller males are less likely to be consumed during pre-copulation; however, larger males may be able to prevent the smaller ones from gaining access to the female.<ref name= "ElgarF"/>
-There exists a conflict of interest between males and females, as females may be more inclined to turn to cannibalism as a source of nutritional intake while the male's interest is mostly focused on ensuring paternity of the future generations.<ref name= "Elgar"/> It was found that cannibalistic females produced offspring with greater survival rates than non-cannibalistic females, as cannibals produced greater [[Clutch (eggs)|clutches]] and larger egg sizes.<ref>Welke, K.W. & Schneider, J.M. 2012, "Sexual cannibalism benefits offspring survival", Animal Behaviour, vol. 83, no. 1, pp. 201-207.</ref> Hence, species such as the male [[Dolomedes tenebrosus|dark fishing spider]] of the family [[dolomedes]] self-sacrifice and spontaneously die during copulation to facilitate their own consumption by the female, thereby increasing the chance of survivorship of future offspring.<ref>Schwartz, S., Wagner, W. & Hebets, E. 2016, "Males Can Benefit from Sexual Cannibalism Facilitated by Self-Sacrifice", Current
-Biology, vol. 26, no. 20, pp.
--2799.
 </ref>
 [[Sexual dimorphism]] has been theorised to have arisen from sexual selection as smaller males were captured more easily than larger males; however, it is also possible that sexual cannibalism only occurs due to the difference in size between male and females.<ref name= "Elgar"/> Data comparing female and male spider body length shows that there is little support for the prior theory as there is not much correlation between body size and the presence of sexual cannibalism. Not all species of spiders which partake in sexual cannibalism exhibit size dimorphism.<ref name= "Elgar"/>
-The avoidance of sexual cannibalism is present in many male species to increase their rate of survival, whereby the male uses cautionary methods to lower the risk of his consumption.<ref name= "Elgar"/> Male orb weaving spiders would often wait for females to [[Moulting|moult]] or to finish eating before attempting to initiate mating, as the females are less likely to attack.<ref name= "Elgar"/> Males which are vulnerable to post-copulation consumption may gather mating thread to generate a mechanical tension which they could use to spring away after insemination, while other spiders such as the crab spider may tangle the female's legs in webs to reduce the risk of the female capturing him.<ref name= "Elgar"/> Male choice is common in [[Mantidae|mantids]] whereby males were observed to choose fatter females due to the reduced risk of attack and were more hesitant to approach starved females.<ref>Kadoi, M., Morimoto, K. & Takami, Y. 2017, “Male mate choice in a sexually cannibalistic species: male escapes from hungry females in the praying mantid Tenodera angustipennis”, Journal of Ethology, vol. 35, no. 2, pp. 177-185.</ref>
+The avoidance of sexual cannibalism is present in many male species to increase their rate of survival, whereby the male uses cautionary methods to lower the risk of his consumption.<ref name= "Elgar"/> Male orb weaving spiders would often wait for females to [[Moulting|moult]] or to finish eating before attempting to initiate mating, as the females are less likely to attack.<ref name= "Elgar"/> Males which are vulnerable to post-copulation consumption may gather mating thread to generate a mechanical tension which they could use to spring away after insemination, while other spiders such as the crab spider may tangle the female's legs in webs to reduce the risk of the female capturing him.<ref name= "Elgar"/> Male choice is common in [[Mantidae|mantids]] whereby males were observed to choose fatter females due to the reduced risk of attack and were more hesitant to approach starved females.<ref>
+{{cite journal|author=Kadoi, M., Morimoto, K. & Takami, Y. 2017|title=Male mate choice in a sexually cannibalistic species: male escapes from hungry females in the praying mantid ''Tenodera angustipennis''|journal=Journal of Ethology|volume=35|issue=2|pages=177–185|pmc=5711982|doi=10.1007/s10164-017-0506-z|pmid=29225403|year=2017}}</ref>
 == Size-structured cannibalism ==
-[[File:Mononchidae eating a Mononchidae 1.jpg|200px|thumb|[[Nematode]] [[Mononchidae]] eating another Mononchidae.]]
+[[File:Mononchidae eating a Mononchidae 1.jpg|thumb|[[Nematode]] [[Mononchidae]] eating another Mononchidae.]]
-Size-structured cannibalism is cannibalism in which older, larger, more mature individuals consume smaller, younger [[conspecific]]s. In size-structured populations, (where populations are made of individuals of various sizes, ages, and maturities), cannibalism can be responsible for 8% ([[Belding's ground squirrel]]) to 95% ([[dragonfly]] [[larva]]e) of the total mortality,<ref>G. A. Polis, The evolution and dynamics of intraspecific predation. Annual Review of Ecology and Systematics 12, 225-251 (1981)</ref> making it a significant and important factor for population<ref>David Claessen, A. M. De Roos, and L. Persson, Population dynamic theory of size-dependent cannibalism. Proceedings of the Royal Society of London Series B-Biological Sciences 271 (1537), 333-340 (2004)</ref> and community dynamics.<ref>V. H. W. Rudolf, Consequences of stage-structured predators: Cannibalism, behavioral effects and trophic cascades. Ecology 88, 2991-3003 (2007)</ref>
+Size-structured cannibalism is cannibalism in which older, larger, more mature individuals consume smaller, younger [[conspecific]]s. In size-structured populations, (where populations are made of individuals of various sizes, ages, and maturities), cannibalism can be responsible for 8% ([[Belding's ground squirrel]]) to 95% ([[dragonfly]] [[larva]]e) of the total mortality,<ref name="PolisThe"/> making it a significant and important factor for population<ref>{{cite journal|pmid=15101690|year=2004|last1=Claessen|first1=D.|last2=De Roos|first2=A. M.|last3=Persson|first3=L.|title=Population dynamic theory of size-dependent cannibalism|journal=Proceedings. Biological Sciences|volume=271|issue=1537|pages=333–40|doi=10.1098/rspb.2003.2555|pmc=1691603}}</ref> and community dynamics.<ref>{{cite journal|pmid=18229834|year=2007|last1=Rudolf|first1=V. H.|title=Consequences of stage-structured predators: Cannibalism, behavioral effects, and trophic cascades|journal=Ecology|volume=88|issue=12|pages=2991–3003|doi=10.1890/07-0179.1}}</ref>
-Size-structured cannibalism has commonly been observed in the wild for a variety of [[taxa]]. Vertebrate examples include [[chimpanzee]]s, where groups of adult males have been observed to attack and consume infants.<ref>A. C. Arcadi and R. W. Wrangham, Infanticide in chimpanzees: Review of cases and a new within-group observation from the Kanyawara study group in [[Kibale National Park]]. Primates 40 (2), 337-351 (1999).</ref><ref>M. L. Wilson, W. R. Wallauer, and A. E. Pusey, New cases of intergroup violence among chimpanzees in Gombe National Park, Tanzania. International Journal of Primatology 25 (3), 523-549 (2004).</ref><ref>D. P. Watts, J. C. Mitani, and H. M. Sherrow, New cases of inter-community infanticide by male chimpanzees at Ngogo, Kibale National Park, Uganda. Primates 43 (4), 263-270 (2002)</ref>
+Size-structured cannibalism has commonly been observed in the wild for a variety of [[taxa]]. Vertebrate examples include [[chimpanzee]]s, where groups of adult males have been observed to attack and consume infants.<ref>{{cite journal|doi=10.1007/BF02557557|title=Infanticide in chimpanzees: Review of cases and a new within-group observation from the Kanyawara study group in Kibale National Park|year=1999|last1=Arcadi|first1=Adam Clark|last2=Wrangham|first2=Richard W.|journal=Primates|volume=40|issue=2|pages=337–351}}</ref><ref>{{cite journal|doi=10.1023/B:IJOP.0000023574.38219.92|title=New Cases of Intergroup Violence Among Chimpanzees in Gombe National Park, Tanzania|year=2004|last1=Wilson|first1=Michael L.|last2=Wallauer|first2=William R.|last3=Pusey|first3=Anne E.|journal=International Journal of Primatology|volume=25|issue=3|pages=523–549}}</ref><ref>{{cite journal|doi=10.1007/BF02629601|pmid=12426461|title=New cases of inter-community infanticide by Male Chimpanzees at Ngogo, Kibale National Park, Uganda|year=2002|last1=Watts|first1=David P.|last2=Sherrow|first2=Hogan M.|last3=Mitani|first3=John C.|journal=Primates|volume=43|issue=4|pages=263–270}}</ref>
 === Filial cannibalism ===
 {{main|Filial cannibalism}}
-Filial cannibalism is a specific type of size-structured cannibalism in which adults eat their own offspring.<ref name="Rohwer, S 1978">Rohwer, S. 1978. Parent Cannibalism of Offspring and Egg Raiding as a Courtship Strategy. American Naturalist 112:429-440.</ref> Although most often thought of as parents eating live young, filial cannibalism includes parental consumption of [[Stillbirth|stillborn]] infants and [[miscarriage|miscarried]] fetuses as well as infertile and still-incubating eggs. Vertebrate examples include [[pig]]s, where [[savaging]] accounts for a sizable percentage of total piglet deaths, and [[cat]]s.<ref>{{Cite web|url=http://messybeast.com/kill_kit.htm|title=CATS THAT KILL KITTENS|website=messybeast.com}}</ref>
+Filial cannibalism is a specific type of size-structured cannibalism in which adults eat their own offspring.<ref name="Rohwer, S 1978">{{cite journal|doi=10.1086/283284|title=Parent Cannibalism of Offspring and Egg Raiding as a Courtship Strategy|year=1978|last1=Rohwer|first1=Sievert|journal=The American Naturalist|volume=112|issue=984|pages=429–440}}</ref> Although most often thought of as parents eating live young, filial cannibalism includes parental consumption of [[Stillbirth|stillborn]] infants and [[miscarriage|miscarried]] fetuses as well as infertile and still-incubating eggs. Vertebrate examples include [[pig]]s, where [[savaging]] accounts for a sizable percentage of total piglet deaths, and [[cat]]s.<ref>{{Cite web|url=http://messybeast.com/kill_kit.htm|title=CATS THAT KILL KITTENS|website=messybeast.com}}</ref>
-Filial cannibalism is particularly common in [[teleost]] fishes, appearing in at least seventeen different families of teleosts.<ref>Manica, A. 2002. Filial cannibalism in teleost fish. Biological Reviews 77:261-277.</ref> Within this diverse group of fish, there have been many, variable explanations of the possible adaptive value of filial cannibalism. One of these is the energy-based hypothesis, which suggests that fish eat their offspring when they are low on energy as an investment in future reproductive success.<ref name="Rohwer, S 1978"/> This has been supported by experimental evidence, showing that male [[three-spined stickleback]]s,<ref name="Rohwer, S 1978"/><ref name="Mehlis, M. 2010">Mehlis, M., T. C. M. Bakker, L. Engqvist, and J. G. Frommen. 2010. To eat or not to eat: egg-based assessment of paternity triggers fine-tuned decisions about filial cannibalism. Proceedings of the Royal Society B-Biological Sciences 277:2627-2635.</ref><ref>Mehlis, M., T. C. M. Bakker, and J. G. Frommen. 2009. Nutritional benefits of filial cannibalism in three-spined sticklebacks (Gasterosteus aculeatus). Naturwissenschaften 96:399-403.</ref> male [[tessellated darter]]s,<ref>DeWoody, J. A., D. E. Fletcher, S. D. Wilkins, and J. C. Avise. 2001. Genetic documentation of filial cannibalism in nature. Proceedings of the National Academy of Sciences of the United States of America 98:5090-5092.</ref> and male [[sphinx blenny]] fish<ref>Kraak, S. B. M. 1996. Female preference and filial cannibalism in Aidablennius sphynx (Teleostei, Blenniidae); a combined field and laboratory study. Behavioural Processes 36:85-97.</ref> all consume or absorb their own eggs to maintain their physical conditions. In other words, when males of a fish species are low on energy, it might sometimes be beneficial for them to feed on their own offspring to survive and invest in future reproductive success.
+Filial cannibalism is particularly common in [[teleost]] fishes, appearing in at least seventeen different families of teleosts.<ref>{{cite journal|pmid=12056749|year=2002|last1=Manica|first1=A.|title=Filial cannibalism in teleost fish|journal=Biological Reviews of the Cambridge Philosophical Society|volume=77|issue=2|pages=261–77|doi=10.1017/s1464793101005905}}</ref> Within this diverse group of fish, there have been many, variable explanations of the possible adaptive value of filial cannibalism. One of these is the energy-based hypothesis, which suggests that fish eat their offspring when they are low on energy as an investment in future reproductive success.<ref name="Rohwer, S 1978"/> This has been supported by experimental evidence, showing that male [[three-spined stickleback]]s,<ref name="Rohwer, S 1978"/><ref name="Mehlis, M. 2010">{{cite journal|pmid=20410042|year=2010|last1=Mehlis|first1=M.|last2=Bakker|first2=T. C.|last3=Engqvist|first3=L.|last4=Frommen|first4=J. G.|title=To eat or not to eat: Egg-based assessment of paternity triggers fine-tuned decisions about filial cannibalism|journal=Proceedings. Biological Sciences|volume=277|issue=1694|pages=2627–35|doi=10.1098/rspb.2010.0234|pmc=2982036}}</ref><ref>
+{{cite journal|title= Nutritional benefits of filial cannibalism in three-spined sticklebacks (''Gasterosteus aculeatus'')|pmid=19066836|year=2009|last1=Mehlis|first1=M.|last2=Bakker|first2=T. C.|last3=Frommen|first3=J. G.|journal=Die Naturwissenschaften|volume=96|issue=3|pages=399–403|doi=10.1007/s00114-008-0485-6|bibcode=2009NW.....96..399M}}</ref> male [[tessellated darter]]s,<ref>{{cite journal|doi=10.1073/pnas.091102598|pmid=11309508|pmc=33168|bibcode=2001PNAS...98.5090D|title=Genetic documentation of filial cannibalism in nature|year=2001|last1=Dewoody|first1=J. A.|last2=Fletcher|first2=D. E.|last3=Wilkins|first3=S. D.|last4=Avise|first4=J. C.|journal=Proceedings of the National Academy of Sciences|volume=98|issue=9|pages=5090–5092}}</ref> and male [[sphinx blenny]] fish<ref>
+{{cite journal|author=Kraak, S. B. M. |title= Female preference and filial cannibalism in ''Aidablennius sphynx'' (Teleostei, Blenniidae); a combined field and laboratory study|journal= Behavioural Processes|volume= 36|issue= 1|pages= 85–97|pmid=24896420|year= 1996|doi= 10.1016/0376-6357(95)00019-4}}</ref> all consume or absorb their own eggs to maintain their physical conditions. In other words, when males of a fish species are low on energy, it might sometimes be beneficial for them to feed on their own offspring to survive and invest in future reproductive success.
-Another hypothesis as to the adaptive value of filial cannibalism in [[teleost]]s is that it increases density-dependent egg survivorship. In other words, filial cannibalism simply increases overall reproductive success by helping the other eggs make it to maturity by thinning out the numbers. Possible explanations as to why this is so include increasing oxygen availability to the remaining eggs,<ref>Payne, A. G., C. Smith, and A. C. Campbell. 2002. Filial cannibalism improves survival and development of beaugregory damselfish embryos. Proceedings of the Royal Society of London Series B-Biological Sciences 269:2095-2102.</ref> the negative effects of accumulating embryo waste,<ref name="Klug, H. 2006">Klug, H., K. Lindstrom, and C. M. S. Mary. 2006. Parents benefit from eating offspring: density-dependent egg survivorship compensates for filial cannibalism. Evolution 60:2087-2095.</ref> and predation.<ref name="Klug, H. 2006"/>
+Another hypothesis as to the adaptive value of filial cannibalism in [[teleost]]s is that it increases density-dependent egg survivorship. In other words, filial cannibalism simply increases overall reproductive success by helping the other eggs make it to maturity by thinning out the numbers. Possible explanations as to why this is so include increasing oxygen availability to the remaining eggs,<ref>{{cite journal|pmid=12396483|year=2002|last1=Payne|first1=A. G.|last2=Smith|first2=C.|last3=Campbell|first3=A. C.|title=Filial cannibalism improves survival and development of beaugregory damselfish embryos|journal=Proceedings. Biological Sciences|volume=269|issue=1505|pages=2095–102|doi=10.1098/rspb.2002.2144|pmc=1691142}}</ref> the negative effects of accumulating embryo waste,<ref name="Klug, H. 2006">{{cite journal|doi=10.1554/05-283.1 |pmid=17133865 |title=Parents Benefit from Eating Offspring: Density-Dependent Egg Survivorship Compensates for Filial Cannibalism |year=2006 |last1=Klug |first1=Hope |last2=Lindström |first2=Kai |last3=St. Mary |first3=Colette M. |journal=Evolution |volume=60 |issue=10 |pages=2087–95 }}</ref> and predation.<ref name="Klug, H. 2006"/>
-In some species of eusocial wasps, such as ''[[Polistes chinensis]]'', the reproducing female will kill and feed younger larvae to her older brood. This occurs under food stressed conditions in order to ensure that the first generation of workers emerges without delay.<ref>Kudo, K.; Shirai, A. (5 January 2012). "Effect of food availability on larval cannibalism by foundresses of the paper wasp Polistes chinensis antennalis". Insect Soc. 59: 279–284.</ref>
+In some species of eusocial wasps, such as ''[[Polistes chinensis]]'', the reproducing female will kill and feed younger larvae to her older brood. This occurs under food stressed conditions in order to ensure that the first generation of workers emerges without delay.<ref>
+{{cite journal|author=Kudo, K.; Shirai, A. |title=Effect of food availability on larval cannibalism by foundresses of the paper wasp ''Polistes chinensis antennalis''|journal=Insectes Sociaux|volume=59|issue=2|pages=279–284|doi=10.1007/s00040-011-0217-3|year=2012}}</ref>
-Further evidence also suggests that occasionally filial cannibalism might be the unfortunate by-product of [[cuckoldry in fish]]. Males consume broods, which may include their own offspring, when they believe a certain percentage of the brood contains genetic material that is not theirs.<ref name="Mehlis, M. 2010"/><ref>Gray, S. M., L. M. Dill, and J. S. McKinnon. 2007. Cuckoldry incites cannibalism: male fish turn to cannibalism when perceived certainty of paternity decreases. American Naturalist 169:258-263.</ref>
+Further evidence also suggests that occasionally filial cannibalism might be the unfortunate by-product of [[cuckoldry in fish]]. Males consume broods, which may include their own offspring, when they believe a certain percentage of the brood contains genetic material that is not theirs.<ref name="Mehlis, M. 2010"/><ref>{{cite journal|doi=10.1086/510604|pmid=17211808|title=Cuckoldry Incites Cannibalism: Male Fish Turn to Cannibalism when Perceived Certainty of Paternity Decreases|year=2007|last1=Gray|first1=Suzanne M.|last2=Dill|first2=Lawrence M.|last3=McKinnon|first3=Jeffrey S.|journal=The American Naturalist|volume=169|issue=2|pages=258–263}}</ref>
-It is not always the parent that cannibalises the offspring, in some spiders mothers have been observed to feed themselves to their brood as the ultimate provision from mother to children, known as matriphagy. <ref>{{Cite web|url=https://www.earthtouchnews.com/wtf/wtf/meet-the-spider-mom-that-makes-a-meal-of-herself|title=Meet the spider mom that makes a meal of herself {{!}} WTF!? {{!}} Earth Touch News|website=Earth Touch News Network|language=en|access-date=2019-08-24}}</ref>
+It is not always the parent that cannibalises the offspring, in some spiders mothers have been observed to feed themselves to their brood as the ultimate provision from mother to children, known as matriphagy. <ref>{{Cite web|url=https://www.earthtouchnews.com/wtf/wtf/meet-the-spider-mom-that-makes-a-meal-of-herself|title=Meet the spider mom that makes a meal of herself {{!}} WTF!? {{!}} Earth Touch News|website=Earth Touch News Network|access-date=2019-08-24}}</ref>
 The [[dinosaur]] ''[[Coelophysis]]'' was once suspected to practice this form of cannibalism but this turned out to be wrong, although ''[[Deinonychus]]'' may have done. Skeletal remains from subadults with missing parts are suspected of having been eaten by other ''Deinonychus'', mainly full-grown adults.
@@ Line 94: / Line 94: @@
 Infanticide is the killing of a non-adult animal by an adult of the same species. Infanticide is often, but not always, accompanied by cannibalism. It is often displayed in [[lion]]s; a male lion encroaching on the territory of a rival pride will often kill any existing cubs fathered by other males; this brings the lionesses into heat more quickly, enabling the invading lion to sire his own young. This is a good example of cannibalistic behavior in a genetic context.
-In many species of [[Lepidoptera]], such as ''[[Small blue|Cupido minimus]]'' and the [[Indian mealmoth]], the first larvae to hatch will consume the other eggs or smaller larvae on the host plant, decreasing competition.<ref>{{Cite web|url=http://www.ukbutterflies.co.uk/species.php?species=minimus|title=Small Blue|last=Eeles|first=Peter|website=UK Butterflies}}</ref><ref>{{Cite journal|last=Boots|first=Michael|date=1998-05-01|title=Cannibalism and the stage-dependent transmission of a viral pathogen of the Indian meal moth, Plodia interpunctella|journal=Ecological Entomology|language=en|volume=23|issue=2|pages=118–122|doi=10.1046/j.1365-2311.1998.00115.x|issn=1365-2311}}</ref>
+In many species of [[Lepidoptera]], such as ''[[Small blue|Cupido minimus]]'' and the [[Indian mealmoth]], the first larvae to hatch will consume the other eggs or smaller larvae on the host plant, decreasing competition.<ref>{{Cite web|url=http://www.ukbutterflies.co.uk/species.php?species=minimus|title=Small Blue|last=Eeles|first=Peter|website=UK Butterflies}}</ref><ref>{{Cite journal|last=Boots|first=Michael|date=1998|title=Cannibalism and the stage-dependent transmission of a viral pathogen of the Indian meal moth, ''Plodia interpunctella''|journal=Ecological Entomology|volume=23|issue=2|pages=118–122|doi=10.1046/j.1365-2311.1998.00115.x}}</ref>
 == Intrauterine cannibalism ==
@@ Line 102: / Line 102: @@
 In '''adelphophagy<!--redirects here-->''' or embryophagy, the fetus eats sibling embryos, while in [[oophagy]] it feeds on eggs.<ref>{{cite book |first=Thierry |last=Lodé |authorlink=Thierry Lodé |year=2001 |title=Les stratégies de reproduction des animaux |trans-title=Reproduction Strategies in Animal Kingdom |publisher=Eds Dunod Sciences |location=Paris |isbn=2-10-005739-1 }}</ref><ref name=crespi>{{cite journal | last = Crespi | first = Bernard |author2=Christina Semeniuk | title = Parent-Offspring Conflict in the Evolution of Vertebrate Reproductive Mode | journal = The American Naturalist | volume = 163 | issue = 5 | pages = 635–654 | year = 2004 | doi = 10.1086/382734 | id = | pmid = 15122484 }}</ref>
-Adelphophagy occurs in some marine gastropods ([[calyptraeid]]s, [[muricid]]s, [[vermetid]]s, and [[buccinid]]s) and in some marine [[annelid]]s (''[[Boccardia proboscidia]]'' in [[Spionidae]]).<ref>Thomsen O., Collin R. & Carrillo-Baltodano A. (2014). "The Effects of Experimentally Induced Adelphophagy in Gastropod Embryos". ''[[PLOS One]]'' '''9'''(7): e103366. {{doi|10.1371/journal.pone.0103366}}.</ref>
+Adelphophagy occurs in some marine gastropods ([[calyptraeid]]s, [[muricid]]s, [[vermetid]]s, and [[buccinid]]s) and in some marine [[annelid]]s (''[[Boccardia proboscidia]]'' in [[Spionidae]]).<ref>{{cite journal |doi=10.1371/journal.pone.0103366|pmid=25072671|pmc=4114838|bibcode=2014PLoSO...9j3366T|title=The Effects of Experimentally Induced Adelphophagy in Gastropod Embryos|year=2014|last1=Thomsen|first1=Olaf|last2=Collin|first2=Rachel|last3=Carrillo-Baltodano|first3=Allan|journal=PLOS ONE|volume=9|issue=7|pages=e103366}}.</ref>
-Intrauterine cannibalism is known to occur in [[Lamniformes|lamnoid sharks]]<ref>{{cite journal | last = Hamlett | first = William C. |author2=Allison M. Eulitt |author3=Robert L. Jarrell |author4=Matthew A. Kelly  | title = Uterogestation and placentation in elasmobranchs | journal = Journal of Experimental Zoology | volume = 266 | issue = 5 | pages = 347–367 | year = 1993 | url = | doi = 10.1002/jez.1402660504 | id = | accessdate =  }}</ref> such as the [[sand tiger shark]], and in the [[fire salamander]],<ref>{{cite book | last = Stebbins | first = Robert C. | authorlink = Robert C. Stebbins | author2 = Nathan W. Cohen | title = A Natural History of Amphibians | publisher = Princeton University Press | year = 1995 | location = Princeton, NJ | isbn = 978-0-691-10251-1 | page = [https://archive.org/details/naturalhistoryof00robe/page/9 9] | url-access = registration | url = https://archive.org/details/naturalhistoryof00robe/page/9 }}</ref> as well as in some [[teleost]] fishes.<ref name="crespi"/>  The [[Carboniferous]] period [[chimaera]], ''[[Delphyodontos]] dacriformes'', is suspected of having practiced intrauterine cannibalism, also, due to the sharp teeth of the recently born (or possibly aborted) juveniles, and the presence of [[fecal]] matter in the juveniles' intestines.<ref>{{cite journal |last=Lund |first=R. |year=1980 |title=Viviparity and intrauterine feeding in a new holocephalan fish from the Lower Carboniferous of Montana |journal=[[Science (journal)|Science]] |volume=209 |issue=4457 |pages=697–699 |doi=10.1126/science.209.4457.697 |pmid=17821193 }}</ref>
+Intrauterine cannibalism is known to occur in [[Lamniformes|lamnoid sharks]]<ref>{{cite journal | last = Hamlett | first = William C. |author2=Allison M. Eulitt |author3=Robert L. Jarrell |author4=Matthew A. Kelly  | title = Uterogestation and placentation in elasmobranchs | journal = Journal of Experimental Zoology | volume = 266 | issue = 5 | pages = 347–367 | year = 1993 | url = | doi = 10.1002/jez.1402660504 | id = | accessdate =  }}</ref> such as the [[sand tiger shark]], and in the [[fire salamander]],<ref>{{cite book | last = Stebbins | first = Robert C. | authorlink = Robert C. Stebbins | author2 = Nathan W. Cohen | title = A Natural History of Amphibians | publisher = Princeton University Press | year = 1995 | location = Princeton, NJ | isbn = 978-0-691-10251-1 | page = [https://archive.org/details/naturalhistoryof00robe/page/9 9] | url-access = registration | url = https://archive.org/details/naturalhistoryof00robe/page/9 }}</ref> as well as in some [[teleost]] fishes.<ref name="crespi"/>  The [[Carboniferous]] period [[chimaera]], ''[[Delphyodontos]] dacriformes'', is suspected of having practiced intrauterine cannibalism, also, due to the sharp teeth of the recently born (or possibly aborted) juveniles, and the presence of [[fecal]] matter in the juveniles' intestines.<ref>{{cite journal |last=Lund |first=R. |year=1980 |title=Viviparity and intrauterine feeding in a new holocephalan fish from the Lower Carboniferous of Montana |journal=[[Science (journal)|Science]] |volume=209 |issue=4457 |pages=697–699 |doi=10.1126/science.209.4457.697 |pmid=17821193 |bibcode=1980Sci...209..697L }}</ref>
 ==Protection against cannibalism==
-Animals have evolved protection to prevent and deter potential predators such as those from their own kind.<ref name= "Elgar"/> Many amphibian eggs are gelatinous and toxic to decrease edibility. Often, adults would lay their eggs in crevices, holes, or empty nesting sites to hide their eggs from potential conspecific predators which tend to ingest the eggs for an additional nutritional benefit or to get rid of genetic competition. In amphibians, the development of non-aquatic egg deposition has helped increase the survival rates of their young by the evolution of viviparity or direct development.<ref name= "Elgar"/> In bees, worker policing occurs to prohibit worker reproduction, whereby workers cannibalize other worker laid eggs.<ref name="Santomauro">{{cite journal |last=Santomauro |first=G. |last2=Oldham |first2=N. J. |last3=Boland |first3=W. |last4=Engels |first4=W. |lastauthoramp=yes |year=2004 |title=Cannibalism of diploid drone larvae in the honey bee (Apis mellifera) is released by odd pattern of cuticular substances |journal=Journal of Apicultural Research |volume=43 |issue=2 |pages=69–74 |doi=10.1080/00218839.2004.11101114 }}</ref> Queen laid eggs have a different scent than worker laid eggs, allowing workers to differentiate between the two, allowing them to nurture and protect queen laid eggs rather than cannibalising them.<ref name="Santomauro" /> Parental presence at nesting sites is also a common method of protection against infanticide committed by conspecific individuals, whereby the parent exhibits defensive displays to ward off potential predators. Parental investment in newborns are generally higher during their early stages of development whereby behaviours such as aggression, territorial behaviour, and pregnancy blocking become more apparent.<ref name= "Elgar"/>
+Animals have evolved protection to prevent and deter potential predators such as those from their own kind.<ref name= "Elgar"/> Many amphibian eggs are gelatinous and toxic to decrease edibility. Often, adults would lay their eggs in crevices, holes, or empty nesting sites to hide their eggs from potential conspecific predators which tend to ingest the eggs for an additional nutritional benefit or to get rid of genetic competition. In amphibians, the development of non-aquatic egg deposition has helped increase the survival rates of their young by the evolution of viviparity or direct development.<ref name= "Elgar"/> In bees, worker policing occurs to prohibit worker reproduction, whereby workers cannibalize other worker laid eggs.<ref name="Santomauro">{{cite journal |last=Santomauro |first=G. |last2=Oldham |first2=N. J. |last3=Boland |first3=W. |last4=Engels |first4=W. |lastauthoramp=yes |year=2004 |title=Cannibalism of diploid drone larvae in the honey bee (''Apis mellifera'') is released by odd pattern of cuticular substances |journal=Journal of Apicultural Research |volume=43 |issue=2 |pages=69–74 |doi=10.1080/00218839.2004.11101114 }}</ref> Queen laid eggs have a different scent than worker laid eggs, allowing workers to differentiate between the two, allowing them to nurture and protect queen laid eggs rather than cannibalising them.<ref name="Santomauro" /> Parental presence at nesting sites is also a common method of protection against infanticide committed by conspecific individuals, whereby the parent exhibits defensive displays to ward off potential predators. Parental investment in newborns are generally higher during their early stages of development whereby behaviours such as aggression, territorial behaviour, and pregnancy blocking become more apparent.<ref name= "Elgar"/>
-Morphological plasticity helps an individual account for different predation stresses, thereby increasing individual survival rates.<ref name="Kishida">{{cite journal |last=Kishida |first=O. |last2=Trussell |first2=G. C. |last3=Nishimura |first3=K. |last4=Ohgushi |first4=T. |lastauthoramp=yes |year=2009 |title=Inducible Defenses in Prey Intensify Predator Cannibalism |journal=[[Ecology (journal)|Ecology]] |volume=90 |issue=11 |pages=3150–3158 |doi=10.1890/08-2158.1 |hdl=2115/44963 }}</ref> Japanese brown frog tadpoles have been shown to exhibit morphological plasticity when they are in a high stress environment where cannibalism between tadpoles and more developed individuals were present. Shifting their morphology plays a key role in their survival, creating bulkier bodies when put into environments where more developed tadpoles were present, to make it difficult for the individuals to swallow them whole.<ref name="Kishida" /> Diet shifts between different stages of development have also evolved to decrease competition between each stage, thereby increasing the amount of food availability so that there is a decreased chance that the individuals will turn to cannibalism as an additional food source.<ref name= "Elgar"/>
+Morphological plasticity helps an individual account for different predation stresses, thereby increasing individual survival rates.<ref name="Kishida">{{cite journal |last=Kishida |first=O. |last2=Trussell |first2=G. C. |last3=Nishimura |first3=K. |last4=Ohgushi |first4=T. |lastauthoramp=yes |year=2009 |title=Inducible Defenses in Prey Intensify Predator Cannibalism |journal=[[Ecology (journal)|Ecology]] |volume=90 |issue=11 |pages=3150–3158 |doi=10.1890/08-2158.1 |pmid=19967870 |hdl=2115/44963 }}</ref> Japanese brown frog tadpoles have been shown to exhibit morphological plasticity when they are in a high stress environment where cannibalism between tadpoles and more developed individuals were present. Shifting their morphology plays a key role in their survival, creating bulkier bodies when put into environments where more developed tadpoles were present, to make it difficult for the individuals to swallow them whole.<ref name="Kishida" /> Diet shifts between different stages of development have also evolved to decrease competition between each stage, thereby increasing the amount of food availability so that there is a decreased chance that the individuals will turn to cannibalism as an additional food source.<ref name= "Elgar"/>
 == See also ==