Starfish

From Wikipedia, the free encyclopedia
  (Redirected from Asteroidea)
Jump to: navigation, search
For other uses, see Starfish (disambiguation).
"Asteroidea" redirects here. For the Asteraceae subfamily, see Asteroideae.
"Sea star" redirects here. For the tanker, see MV Sea Star. For the Argentine awards, see Sea Star Awards.
Starfish
Temporal range: Ordovician–Recent
Scientific classification
Kingdom: Animalia
Phylum: Echinodermata
Subphylum: Asterozoa
Class: Asteroidea
De Blainville, 1830
Orders

Brisingida
Forcipulatida
Paxillosida
Notomyotida
Spinulosida
Valvatida
Velatida [1]
† Calliasterellidae
† Trichasteropsida[2]

Starfish or sea stars are echinoderms belonging to the class Asteroidea.[3] The names "starfish" and "sea star" essentially refer to members of the class Asteroidea. However, common usage frequently finds these names also applied to ophiuroids, which are correctly referred to as "brittle stars" or "basket stars". About 1,800 living species of starfish occur in all the world's oceans, including the Atlantic, Pacific, Indian, Arctic and Southern Ocean regions. The fossil record for starfish is rather poor; the ossicles and spines are the only parts of the animal likely to be preserved after death and the oldest known fossils are from the Ordovician. Starfish occur across a broad depth range from the intertidal to abyssal depths of greater than 6,000 m (20,000 ft).

Starfish are among the most familiar of marine animals found on the seabed. They typically have a central disc and five arms, though some species have many more arms than this. The aboral or upper surface may be smooth, granular or spiny, and is covered with overlapping plates. Many species are brightly coloured in various shades of red or orange, while others are blue, grey, brown, or drab. Starfish have tube feet operated by a hydraulic system and a mouth at the centre of the oral or lower surface. They are opportunistic feeders and are mostly predators on benthic invertebrates. Several species having specialized feeding behaviours, including suspension feeding and adaptations for feeding on specific prey. They have complex life cycles and can reproduce both sexually and asexually. Most can regenerate damaged or lost arms.

The Asteroidea occupy several important ecological roles. Starfish, such as the ochre sea star (Pisaster ochraceus), have become widely known as an example of the keystone species concept in ecology. The tropical crown-of-thorns starfish (Acanthaster planci) is a voracious predator of coral throughout the Indo-Pacific region. Other starfish, such as members of the Asterinidae, are frequently used in developmental biology.

Contents

Symmetry

Red-knobbed starfish (Protoreaster linckii) from the Indian Ocean
Further information: Symmetry in biology

Like all echinoderms, starfish are deuterostomes in their embryonic development, a feature they share with chordates, (including vertebrates), but not with most other invertebrates. Their embryos initially develop bilateral symmetry, again reflecting their likely common ancestry with chordates. Later development takes a very different path however as, when the developing larvae settle out of the zooplankton and undergo metamorphosis, their bodies are reorganised and develop the characteristic radial symmetry of the echinoderm, typically pentamerism.[4] However, the evolutionary ancestors of echinoderms are believed to have been bilateral symmetrical. Modern starfish, as well as other echinoderms, exhibit bilateral symmetry in their larval forms.[5]

Most starfish have five rays or arms, which radiate from a central disc. However, several species frequently have six or more arms. Several asteroid groups, such as the Solasteridae, have 10 to 15 arms, while some species, such as the Antarctic Labidiaster annulatus can have up to 50. It is not unusual for species that typically have five arms to exceptionally possess six or more through abnormal development.[6]

Anatomy

As echinoderms, starfish possess a hydraulic water vascular system that aids in locomotion.[7] This system has many projections called tube feet on the starfish's arms which function in locomotion and aid with feeding. Tube feet emerge through openings in the endoskeleton and are externally expressed through the open grooves present along the oral surface of each arm.[8]

The body cavity also contains the circulatory system, called the hemal system. Hemal channels form rings around the mouth (the oral hemal ring), nearer to the aboral surface and around the digestive system (the gastric hemal ring).[9] A portion of the body cavity, the axial sinus, connects the three rings. Each arm also has hemal channels running next to the gonads.[9] These channels have blind ends with no continuous circulation of the blood.[4]

On the end of each arm is a tiny simple eye, which allows the starfish to perceive the difference between light and darkness and is useful in the detection of moving objects.[10] Only part of each cell is pigmented (making it either red or black), with no cornea or iris. Such an eye is known as a pigment spot ocellus.[11]

Body wall

Sea-star endoskeleton

The body wall consists of a thin cuticle, an epidermis consisting of a single layer of cells, a thick dermis formed of connective tissue and a thin coelomic epithelium which contains the longitudinal and circular musculature and the peritoneum. The dermis contains an endoskeleton of plate-like calcium carbonate components known as ossicles. These are honeycombed structures composed of calcite microcrystals arranged in a lattice. They vary in form, some bearing external granules, tubercles and spines, sometimes organised into definite patterns. Some are specialised structures such as the pedicellariae and paxillae. Pedicellariae are compound ossicles with forceps-like jaws and function to remove debris from the body surface, moving about on their flexible stalks in response to physical or chemical stimuli, continually making biting movements.[12] Paxillae are umbrella-like structures found on starfish which live buried in sediment. They meet edge to edge and form a false cuticle with a water cavity beneath in which the madreporite and delicate gill structures are protected. All the ossicles, including those projecting externally, are covered by the epidermal layer.[13]

Several groups of asteroids, including Valvatida and Forcipulatida, possess pedicellariae.[12] In Forcipulatida such as Asterias and Pisaster, pedicellariae occur in pompom-like tufts at the base of each spine, whereas in the Goniasteridae, such as Hippasteria phrygiana, pedicellariae are scattered over the body surface. Some are thought to assist in defence, while others aid in feeding or in the removal of organisms attempting to settle on the starfish's surface.[14] The Antarctic Labidiaster annulatus uses its large pedicellariae to capture krill, while the North Pacific Stylasterias forreri uses its pedicellariae to capture small fish.[15]

There may also be papulae, thin-walled protrusions of the body cavity that reach through the body wall and extend into the surrounding water. These serve a respiratory function.[4] These structures are supported by collagen fibres set at right angles to each other and arranged in a three-dimensional web with the ossicles and papulae in the interstices. This arrangement enables both easy flexion of the arms by the starfish and the rapid onset of stiffness and rigidity required for actions performed under stress.[16]

Digestive system and excretion

Aboral view of partially dissected starfish
1. Pyloric stomach, 2. Intestine and anus,
3. Rectal sac, 4. Stone canal,
5. Madreporite, 6. Pyloric caecum,
7. Digestive glands, 8. Cardiac stomach,
9. Gonad, 10. Radial canal,
11. Ambulacral ridge

The gut of a starfish occupies most of the disc and extends into the arms. The mouth is located in the centre of the oral surface, where it is surrounded by a tough peristomial membrane and closed with a sphincter. The mouth opens through a short oesophagus into a stomach divided by a constriction into a larger, evertible cardiac portion and a smaller pyloric portion. The cardiac stomach is glandular and pouched, and is supported by ligaments attached to ossicles in the arms, so it can be pulled back into position after it has been everted. The pyloric stomach has two extensions, the pyloric caeca, which are elongated, branched hollow tubes extending into each arm. These are lined by a series of glands which secrete digestive enzymes and absorb nutrients from the food. A short intestine and rectum run from the pyloric stomach to open at a small anus at the apex of the aboral surface of the disc.[17]

Primitive starfish, such as Astropecten and Luidia, swallow their prey whole, and start to digest it in their cardiac stomachs. Shell valves and other inedible materials are ejected through their mouths. The semi-digested fluid is passed into their pyloric stomachs and caeca where digestion continues and absorption occurs.[17] In more advanced species of starfish, the cardiac stomach can be everted from the organism's body to engulf and digest food. When the prey is a clam, the starfish pulls with its tube feet to separate the two valves slightly, and inserts a small section of its stomach, which releases enzymes to digest the prey. The stomach and the partially digested prey are later retracted into the disc. Here the food is passed on to the pyloric stomach, which always remains inside the disc.[9]

Because of this ability to digest food outside the body, starfish can hunt prey much larger than their mouths. Their diets include clams and oysters, arthropods, small fish and gastropod molluscs. Some starfish are not pure carnivores, supplementing their diets with algae or organic detritus. Some of these species are grazers, but others trap food particles from the water in sticky mucus strands that are swept towards the mouth along ciliated grooves.[17]

The main nitrogenous waste product is ammonia. With no distinct excretory organs, excretion is performed through the tube feet and papulae.[18] The body fluid contains phagocytic cells, coelomocytes, which are also found within the hemal and water vascular systems. These cells engulf waste material, and eventually migrate to the tips of the papulae, where a portion of body wall is nipped off and ejected into the surrounding water. Some waste may also be excreted by the pyloric glands and voided with the faeces.[18]

Starfish do not appear to have any mechanisms for osmoregulation, and keep their body fluids at the same salt concentration as the surrounding water. Although some species can tolerate relatively low salinity, the lack of an osmoregulation system probably explains why starfish are not found in fresh water or even in estuarine environments.[18]

Water vascular system

Arm tip of Leptasterias polaris showing tube feet and eyespot

The water vascular system of the starfish is a hydraulic system made up of a network of fluid-filled canals and is concerned with locomotion, adhesion, food manipulation and gas exchange. Water enters the system through the madreporite, a porous, often conspicuous, sieve-like ossicle on the aboral surface. It is linked through a stone canal, often lined with calcareous material, to a ring canal around the mouth opening. A radial canal leads off this and runs along the ambulacral groove in each arm. On either side of this are short lateral canals that branch off alternately to right and left and which end in ampullae. These bulb-shaped organs are joined to tube feet (podia) by short linking canals which pass between the ossicles in the ambulacral groove. There are usually two rows of tube feet but in some species, the lateral canals are alternately long and short and there appear to be four rows. The interior of the whole canal system is lined with cilia.[19]

When longitudinal muscles in the ampullae contract, valves in the lateral canals close and water is forced into the tube feet. These extend to contact the substrate. Although the tube feet resemble suction cups in appearance, the gripping action is a function of adhesive chemicals rather than suction. Other chemicals and relaxation of the ampullae allow for release from the substrate. The tube feet latch on to surfaces and move in a wave, with one arm section attaching to the surface as another releases.[10][20] In some circumstances, the tube feet seem to work as levers, but when moving on vertical surfaces, they form a traction system.[21]

Most starfish cannot move quickly, with the leather star (Dermasterias imbricata) managing just 15 cm (6 in) in a minute.[22] Some burrowing species from the genera Astropecten and Luidia have points rather than suckers on their long tube feet and are capable of much more rapid motion, "gliding" across the ocean floor. The sand star (Luidia foliolata) can travel at a rate of 2.8 m (9 ft 2 in) per minute.[23]

Apart from its function in locomotion, the water vascular system serves to transport oxygen from the tube feet, which act as accessory gills, and also nutrients from the gut to the muscles involved in locomotion.[19] Gas exchange also takes place through other gills known as papulae which are thin-walled bulges on the aboral surface of disc and arms. Oxygen gets transferred from these to the coelomic fluid which acts as the transport medium for gasses. Oxygen dissolved in the water is distributed through the body mainly by the fluid in the main body cavity; the hemal system may also play a minor role.[18]

Nervous system

Although starfish do not have many well-defined sense organs, they are sensitive to touch, light, temperature, orientation and the status of the water around them. The tube feet, spines and pedicellariae are sensitive to touch. The tube feet, especially those at the tips of the rays, are also sensitive to chemicals, enabling the starfish to detect odour sources such as food.[24] There are eyespots at the ends of the arms, each one composed of eighty to two hundred simple ocelli. These are composed of pigmented epithelial cells that respond to light, with narrow sensory cells lying between them. They are covered by a thick, transparent cuticle that both protects the ocelli and acts to focus light. Many starfish also possess individual photoreceptor cells in other parts of their bodies and respond to light even when their eyespots are covered. Whether they advance or retreat depends on species.[25]

While starfish lack a centralized brain, their bodies have complex nervous systems which are coordinated by what might be termed a distributed brain. There is a circumoral nerve ring that surrounds the mouth and a radial nerve running along the ambulacral region of each arm parallel to the radial canal. The peripheral nerve system consists of two nerve nets, a sensory system in the epidermis and a motor system in the lining of the coelomic cavity.[26] The ring nerves and radial nerves have sensory and motor components and coordinate the starfish's balance and directional systems.[4] The sensory component receive input from the sensory organs while the motor nerves control the tube feet and musculature. The starfish does not have the capacity to plan its actions. If one arm detects an attractive odour, it becomes dominant and temporarily over-rides the other arms to initiate movement towards the prey. The mechanism for this is not fully understood.[26]

Secondary metabolites

Starfish produce a large number of secondary metabolites in the form of lipids, including steroidal derivatives of cholesterol, and fatty acids, mostly amides of sphingosine. The steroids are mostly saponins, known as asterosaponins, and their sulphated derivatives. They vary between species and are typically formed from up to six sugar molecules (usually glucose and galactose) connected by up to three glycosidic chains. Long-chain fatty acid amides of sphingosine occur frequently and some of them have known pharmacological activity. Various ceramides are also known from starfish and a small number of alkaloids have also been identified. The ecological role in starfish of these chemicals has not been fully investigated, but most have roles in defence and communication. Some are feeding deterrents used by the starfish to discourage predation. Others are antifoulants and supplement the pedicellariae in the prevention of other organisms from settling on the starfish's aboral surface. Some are alarm pheromones and escape-eliciting chemicals, the release of which triggers responses in conspecific starfish but often produces an escape response in potential prey.[27] Research into the efficacy of these compounds for possible pharmacological or industrial use occurs worldwide.[28]

Life cycle

Sexual reproduction

Coscinasterias calamaria in New Zealand

Most species of starfish are dioecious, there being separate male and female individuals. These are usually not distinguishable externally, as the gonads cannot be seen, but their sex is apparent when they are spawning. Some species are simultaneous hermaphrodites (producing eggs and sperm at the same time). In a few of these, the same gonad, called an ovotestis,[29] produces both eggs and sperm. Yet other starfish are sequential hermaphrodites, with some species being protandrous. In these, young individuals are males that change sex into females as they grow older, Asterina gibbosa being an example of these. Others are protogynous and change sex during their lives from female to male. In some species, when a large female divides, the smaller individuals produced become males. When they grow big enough, they change back into females.[30]

Each arm contains two gonads, which release gametes through openings called gonoducts, located on the central disc between the arms. Fertilization is external in most species, though a few show internal fertilization. In most species, the buoyant eggs and sperm are simply released into the water (free spawning) and the resulting embryos and larvae live as part of the plankton. In others, the eggs may be stuck to the undersides of rocks to develop.[31] In certain species of starfish, the females brood their eggs – either by simply enveloping them [31] or by holding them in specialised structures. These structures include chambers on their aboral surfaces,[32] the pyloric stomach (Leptasterias tenera)[33] or even the gonads themselves.[29] Those starfish that brood their eggs by covering them usually raise their disc and assume a humped posture.[34] Pteraster militaris broods a few of its young and broadcasts the remaining eggs which are too voluminous to fit into its pouch.[32] In these brooding species, the eggs are relatively large, and supplied with yolk, and they generally, but not always,[29] develop directly into miniature starfish without an intervening larval stage. The developing young are called "lecithotrophic" because they get their nutrition from the yolk, as opposed to planktotrophic larvae which feed on plankton. In Parvulastra parvivipara, an intragonadal brooder, the young starfish obtain their nutrition by eating other eggs and embryos in the brood pouch.[35] Brooding is especially common in polar and deep-sea species that live in environments unfavourable for larval development [33][36] and in smaller species that produce few eggs.[37]

Reproduction occurs at different times of year according to species. To increase the chances of their eggs being fertilized, starfish may synchronize their spawning, aggregating in groups [31] or forming pairs.[38] This latter behaviour is called pseudo-copulation [39] and the male climbs on top of the female, placing his arms between hers, and releases sperm into the water. This stimulates her to release her eggs. Starfish may use environmental signals to coordinate the time of spawning (day length to indicate the correct time of the year, dawn or dusk to indicate the correct time of day), and chemical signals to indicate their readiness to breed to each other.[40] In some species, mature females produce chemicals to attract sperm in the sea water.[40]

Larval development

Three kinds of bilaterally symmetric starfish larvae (from left to right) scaphularia larva, bipinnaria larva, brachiolaria larva, all of Asterias sp. Painted by Ernst Haeckel

Most starfish embryos hatch at the blastula stage. The original ball of cells develops a lateral pouch, the archenteron. The entrance to this is known as the blastopore and it will later develop into the anus. Another invagination of the surface will fuse with the tip of the archenteron as the mouth while the interior section will become the gut. At the same time, a band of cilia develops on the exterior. This enlarges and extends around the surface and eventually onto two developing arm-like outgrowths. At this stage the larva is known as a bipinnaria. The cilia are used for locomotion and feeding, their rhythmic beat wafting phytoplankton towards the mouth.[41]

The next stage in development is a brachiolaria larva and involves the growth of three short, additional arms. These are at the anterior end, surround a sucker and have adhesive cells at their tips. Both bipinnaria and brachiolaria larvae are bilaterally symmetrical. When fully developed, the brachiolaria settles on the seabed and attaches itself with a short stalk formed from the ventral arms and sucker. Metamorphosis now takes place with a radical rearrangement of tissues. The left side of the larval body becomes the oral surface of the juvenile and the right side the aboral surface. Part of the gut is retained but the mouth and anus are moved to new positions. Some of the body cavities degenerate but others become the water vascular system and the visceral coelom. The starfish is now pentaradially symmetrical. It casts off its stalk and becomes a free-living juvenile starfish about 1 mm (0.04 in) in diameter.[41] Starfish of the order Paxillosida have no brachiolaria stage, with the bipinnaria larva settling on the seabed and developing directly into a juvenile.[41]

Asexual reproduction

"Comet" of Linckia guildingi, showing starfish body regrowing from a single arm
Main article: Asexual reproduction in starfish

Some species of starfish also reproduce asexually as adults either by fission[42] of their central discs or by the autotomy of their arms. The type of reproduction depends on the genus. Among starfish that regenerate whole bodies from their arms, some can do so even from fragments just 1 cm long.[43] Single arms that are regenerating the disc and other arms are called comet forms. The division of the starfish either across their discs or at their arms is usually accompanied by changes that help them break easily.[44]

The larvae of several starfish species can also reproduce asexually.[45] They do this by autotomising some parts of their bodies or by budding.[46] When the larvae sense plentiful food, they favour asexual reproduction instead of directly developing.[47] Though this costs the larvae time and energy, it allows a single larva to give rise to multiple adults when the conditions are right.[48]

Regeneration

Sunflower seastar regenerating arms lost to predators

Some[43] species of starfish have the ability to regenerate lost arms and can regrow an entire new limb given time. Some species can regrow a complete new disc from a single arm,[49] while others need at least part of the central disc to be attached to the detached part.[49] Regrowth can take several months or years.[43][49] Starfish are vulnerable to infections during the early stages after the loss of an arm.[43] A separated limb lives off stored nutrients until it regrows a disc and mouth and is able to feed again. Other than fragmentation carried out for the purpose of reproduction, the division of the body may happen inadvertently due to being detached by a predator, or part may be actively shed by the starfish in an escape response, a process known as autotomy. The loss of parts of the body is achieved by the rapid softening of a special type of connective tissue in response to nervous signals. This type of tissue is called catch connective tissue and is found in most echinoderms.[50][51]

Lifespan

The lifespans of starfish vary considerably between species, generally being longer in larger species and for those with planktonic larvae. For example, Leptasterias hexactis broods a small number of large-yolked eggs. It has an adult weight of 20 g (0.7 oz), reaches sexual maturity in two years and lives for about 10 years in total. Pisaster ochraceus releases a large number of eggs each year and has an adult weight of 80 g (2.8 oz). It reaches maturity in five years and may live to the age of 34.[41]

Ecology

Distribution and habitat

A royal starfish (Astropecten articulatus) on the beach

Echinoderms maintain a delicate internal electrolyte balance in their bodies and this is only possible in a marine environment. This means starfish occur in all of the Earth's oceans, but are not found in any freshwater habitats.[10] The greatest variety of species is found in the tropical Indo-Pacific. Other areas known for their great diversity include the tropical-temperate regions around Australia, the tropical East Pacific and the cold-temperate water of the North Pacific (California to Alaska). All starfish live on the sea bed, but their larvae are planktonic, which allows them to disperse to new locations. Habitats range from tropical coral reefs, rocks, shell brash, gravel, mud, and sand to kelp forests, seagrass meadows and the deep-sea floor.[52]

Diet

Pisaster ochraceus consuming a mussel in central California

Most species are generalist predators, eating mollusks such as clams, oysters, some snails, or any other animal too slow to evade their attack (e.g. other echinoderms, or dying fish). Some species are detritivores, eating decomposing animal and plant material or organic films attached to substrates. Others, such as members of the order Brisingida, feed on sponges or plankton and suspended organic particles. The crown-of-thorns starfish consumes coral polyps.[53]

The processes of feeding and capture may be aided by special parts; Pisaster brevispinus, the short-spined pisaster from the West Coast of America, may use a set of specialized tube feet to dig itself deep into the soft substrata to extract prey (usually clams).[54] Grasping the shellfish, the starfish slowly pries open the prey's shell by wearing out its adductor muscle, and then inserts its everted stomach into an opening to devour the soft tissues. The gap between the valves need only be a fraction of a millimetre wide for the stomach to gain entry.[10]

Ecological impact

Starfish are considered keystone species in their respective marine communities. Their relatively large sizes, diverse diets, indeterminate growth and ability to adapt to different environments gives them great ecological importance.[55] The term "keystone species" was in fact first used by Robert Paine in 1966 to describe a starfish, Pisaster ochraceus.[56] When studying the low intertidal coasts of Washington state, Paine found that predation by P. ochraceus was a major factor in the diversity of species. Experimental removals of this top predator from a stretch of shoreline resulted in lower species diversity and the eventual domination of Mytilus mussels, which were able to outcompete others for space and resources.[57] Similar results were found in a 1971 study of Stichaster australis on the intertidal coast of the South Island of New Zealand, S. australis was found to have removed a majority of transplanted mussels within two or three months of their placement, while the mussels expanded within six months to cover 20-30% of the low zone when S. australis was removed. Without their predation, the mussels overwhelmed the area, threatening biodiversity.[58]

The feeding activity of migratory Oreaster reticulatus on the sandy and seagrass bottoms in Virgin Islands appears to regulate the diversity, distribution and abundance of micro-organisms. Micro-organisms that are unable to withstand periodic decimation of the sediment are weeded out and those that can quicky colonize "clean" sediment may flourish. In addition, foraging by these migratory starfish creates diverse patches of organic matter which may play a role in the distribution and abundance of macro-organisms that feed on the sediment bottom like fish, crabs and sea urchins.[59]

Starfish can also have negative effects on ecosystems. Outbreaks of crown-of-thorns starfish have caused damage to coral reefs in Northeast Australia and French Polynesia.[60][61] A study in Polynesia found that coral cover declined drastically with the arrival of a starfish colony in 2006, dropping from 50% to under 5% in three years.[61]

Asterias amurensis is one of the few echinoderm invasive species. Its larvae likely arrived in Tasmania from central Japan via water discharge from ships in the 1980s. The species has since grown in numbers to the point where they threaten commercially important bivalvia populations. As such, they are considered pests,[62] and are on the Invasive Species Specialist Group list of the world's 100 worst invasive species.[63]

Sea gull feeding on starfish

Threats

Starfish may be preyed on by conspecifics, other starfish species, tritons, fish, sea gulls and sea otters.[62][64][65][66] The crown-of-thorns starfish has few predators, being defended by sharp spines, toxins, and bright warning coloration.[67] Several species may suffer wasting diseases caused by the bacteria genus Vibrio. The protozoan Orchitophrya stellarum is known to infect the gonads of starfish, damaging tissue and reducing testis size.[65] Starfish are vulnerable to high temperatures and experiments have shown the feeding and growth rates of individual P. Ochraceus reduce greatly when their body temperatures raise above 23 °C (73 °F) and they die when over 30 °C (86 °F).[68][69] This same species has a unique ability to absorb seawater to keep itself cool when it is exposed to sunlight by a receding tide.[70]

Starfish and other echinoderms pump water directly into their bodies via the water vascular system. This makes them vulnerable to all forms of water pollution, as they have little ability to filter out the toxins and contaminants it contains. Oil spills and similar events often take a toll on echinoderm populations that carry far-reaching consequences for the ecosystem.[71] A 2009 study found that P. ochraceus will not be affected by ocean acidification in the same way as most calcerous marine animals. This normally causes decreased growth due to the increased acidity dissolving calcium carbonate. Researchers found that when P. ochraceus was exposed to 21 °C (70 °F) and 770 ppm CO2 (beyond rises expected in the next century) that they survived. It is thought that this is because the animals' calcium is nodular and so it is able to compensate for the lack of carbonate by growing more fleshy tissue instead.[72]

Taxonomy and evolutionary history

Starfish fossil, Riedaster reicheli, from the Plattenkalk Upper Jurassic limestone, Solnhofen

The Asteroidea are a large, diverse, and speciose class within the phylum Echinodermata. Like other classes in that group, members are characterised by having radial symmetry as adults, usually five-fold symmetry. In contrast, during their early developmental stages, the larvae have bilateral symmetry. Other characteristics of adults are the possession of a water vascular system and having calcareous skeletons consisting of flat plates connected by a mesh of mutable collagen fibres.[73] Asteroids are characterised by a central disc with a number of radiating arms, typically five. The ossicles that form the hard element of the skeletal structure extend from the disc onto the arms in a continuous arrangement which gives the arms a broad base.[74] This is in contrast to the ophiuroids, in which the disc is clearly separated from the long, slender arms.[75]

Asteroids are poorly represented in the fossil record. This may be because the hard skeletal components separate as the animal decays and the soft tissues collapse into distorted, unrecognisable remains. Another reason may be that most asteroids live on hard substrates where conditions are not favourable for fossilisation. The first known asteroids date back to the Ordovician. In the two major Paleozoic extinction events during the late Devonian and late Permian, many species died out. The surviving species diversified rapidly within a time frame of 60 million years during the Early Jurassic and the beginning of the Middle Jurassic.[74] A 2012 study found that speciation in starfish can occur in only 6,000 years.[76]

Diversity

A large eighteen-armed member of Brisingida

Living groups

Species in this order have a small, inflexible disc and between six and 20 long, thin arms which they use for suspension feeding. They have a single series of marginal plates, a fused ring of disc plates, no actinal plates, a spool-like ambulacral column, reduced abactinal plates, crossed pedicellariae, and several series of long spines on the arms. They live almost exclusively in deep-sea habitats, although a few live in shallow waters in the Antarctic.[78][79] In some species, the tube feet have rounded tips and lack suckers.[80]
Common starfish, a member of Forcipulatida
Species in this order have distinctive pedicellariae, consisting of a short stalk with three skeletal ossicles. They tend to have robust bodies[82] and have tube feet with flat-tipped suckers usually arranged in four rows.[80] The order includes well-known species from temperate regions, including the common starfish of North Atlantic coasts and rock pools, as well as cold-water and abyssal species.[83]
These asteroids are deep-sea dwelling and have flexible arms. The inner dorso-lateral surface of the arms contain characteristic longitudinal muscle bands.[85] In some species, the tube feet lack suckers.[80]
Magnificent star, a member of Paxillosida
This is a primitive order and members do not extrude their stomach when feeding, lack an anus and have no suckers on their tube feet. Papulae are plentiful on their aboral surface, they possess marginal plates and have sessile pedicellariae. They mostly inhabit soft-bottomed areas of sand or mud.[82] There is no brachiolaria stage in their larval development.[87] The comb starfish (Astropecten polyacanthus), one of the commonest Indo-Pacific species, is a member of this order.
Cushion star, a member of Valvatida
Most species in this order lack pedicellariae and all have a delicate skeletal arrangement with small or no marginal plates on the disc and arms. They have numerous groups of low spines on the aboral surface.[89][90] This group includes relatively slender five-armed species such as the red starfish Echinaster sepositus and the plump leather star.
Most species in this order have five arms and two rows of tube feet with suckers. There are conspicuous marginal plates on the arms and disc. Some species have paxillae and in some, the main pedicellariae are clamp-like and recessed into the skeletal plates.[90] This group includes the rigid-bodied cushion stars of warm tropical waters and the deep water sea daisies.
This order of asteroids consists mostly of deep-sea and other cold-water starfish often with a global distribution. The shape is pentagonal or star-shaped with five to fifteen arms. They mostly have poorly developed skeletons with papulae widely distributed on the aboral surface and spiny or sessile pedicellariae.[93] This group includes the multi-armed morning sun star and common sunstar.

Extinct groups

Extinct groups within the Asteroidea include:[2]

Phylogeny

The phylogeny of the Asteroidea has proven difficult to resolve.[2] The phylogeny proposed by Gale in 1987 is:[2][96]

† Palaeozoic Asteroids




Paxillosida



Valvatida, including Velatida, Spinulosida (not a clade)[2]


Forcipulatida, including Brisingida





The phylogeny proposed by Blake in 1987 is:[2][97]

† Palaeozoic Asteroids




† Calliasterellidae



† Compasteridae



† Trichasteropsida




Brisingida


Forcipulatida





Spinulosida


Velatida





Notomyotida


Valvatida



Paxillosida









Later work making use of molecular evidence, with or without the use of morphological evidence, had by 2000 failed to resolve the argument.[2] In 2011, on further molecular evidence, Janies and colleagues noted that the phylogeny of the echinoderms "has proven difficult",[98] and that "the overall phylogeny of extant echinoderms remains sensitive to the choice of analytical methods".[98] They presented a phylogenetic tree for the living Asteroidea only; using the traditional names of starfish orders where possible, and indicating "part of" otherwise, the phylogeny is shown below. The Solasteridae are split from the Velatida, and the old Spinulosida is broken up.[98]






Solasteridae and part of Spinulosida, e.g. Stegnaster and part of Valvatida, e.g. Asterina


Odontasteridae, which was a part of Valvatida



Paxillosida



part of Spinulosida, e.g. Echinaster, part of Valvatida, e.g. Archaster




Forcipulatida


Brisingida with part of Velatida, e.g. Caymanostella and part of Forcipulatida, e.g. Stichaster





Velatida except for Solasteridae



Notomyotida (not analysed)

Human relations

In legend and literature

An aboriginal Australian fable retold by the Welsh school headmaster William Jenkyn Thomas (1870–1959)[99] tells how some animals needed a canoe to cross the ocean. Whale had one but refused to lend it, so Starfish kept him busy, telling him stories and grooming him to remove parasites, while the others stole the canoe. When Whale realized the trick he beat Starfish ragged, which is how Starfish still is today.[100]

In 1900, the New Zealand scholar Edward Tregear documented The Creation Song, which he describes as "an ancient prayer for the dedication of a high chief"[101] of Hawaii. Among the "uncreated gods" described early in the song are the male Kumilipo ("Creation") and the female Poele, both born in the night; a coral insect, the earthworm, and "The starfish was born, whose children were starry".[101] The song then names the various types of shellfish.[101]

Georg Eberhard Rumpf's 1705 The Ambonese Curiosity Cabinet describes the tropical varieties of Stella Marina or Bintang Laut, "Sea Star", in Latin and Malay respectively, known in the waters around Ambon. He writes that the Histoire des Antilles reports that when the sea stars "see thunder storms approaching, [they] grab hold of many small stones with their little legs, looking to ... hold themselves down as if with anchors".[102]

Starfish is the title of a number of books. Peter Watts wrote a science fiction book called Starfish in 2008, part of his "Rifters" trilogy.[103] Jennie Orbell wrote a novel of this name in 2012.[104] Alice Addison wrote a non-fiction book subtitled "A year in the life of bereavement and depression".[105] The Starfish and the Spider is a 2006 business management book by Ori Brafman and Rod Beckstrom; its title alludes to the ability of the starfish to regenerate itself because of its decentralized nervous system, and the book suggests ways that a decentralized organization may flourish.[106]

As food

Deep-fried starfish on sale in a food stall in Beijing, 2008

Starfish are widespread in the oceans, but are only occasionally used as food. There may be good reason for this: many species are toxic, as the body wall contains saponins[107] and tetrodotoxins.[108] Some species that prey on bivalve molluscs can transmit paralytic shellfish poisoning.[109] Georg Eberhard Rumpf found few starfish being used for food in the Indonesian archipelago, other than as bait in fish traps, but on "Huamobel" the people cut them up, squeeze out the black blood and cook them with sour tamarind leaves; after resting the pieces for a day or two, they remove the outer skin and cook them in coconut milk.[102] The Amakusa TV company markets an ebook called "Cooking Starfish in Japan", available in English and Japanese, in their guidebook series.[110] Packets of dried starfish, "ヒトデ乾燥品 小袋タイプ 150g" are sold in Japan.[111]

In popular culture

The 1988 album Starfish by the Australian alternative rock band The Church made the band's name, selling 600,000 copies in the United States.[112] The song Starfish-On-The-Toast was composed by the Scottish singer and songwriter Donovan. It formed one of the tracks of his 1967 double album A Gift from a Flower to a Garden. Like the other songs on the second record of the album, For Little Ones, it was played with acoustic instruments, ostensibly for children, according to the album's liner notes.[113] The song includes the lines:

Fine rock pooling coast
this starfish on the toast
the men in the crabbing boats they cry...[114]

In the Nickelodeon animated television series SpongeBob SquarePants, the eponymous character's best friend is a dim-witted starfish, Patrick Star.[115] In the "silly and lame" 2006 Australian-American teen fantasy comedy film Aquamarine,[116] the eponymous mermaid gives each of the two protagonists Hailey and Claire a live starfish earring. The starfish are voiced by Emma Roberts (Claire's), Joanna Levesque (Hailey's), and Sara Paxton (Aquamarine's).[117]

In industry and military history

With its multiple arms, the starfish provides a popular metaphor for computer networks,[118] companies[119][120] and software tools.[121] It is also the name of a seabed imaging system and company.[122]

Starfish has repeatedly been chosen as a name in military history. Three ships of the Royal Navy have borne the name HMS Starfish: an A class destroyer launched in 1894;[123] an R class destroyer launched in 1916;[124] and an S class submarine launched in 1933 and lost in 1940.[125] In the Second World War, Starfish sites were large scale night-time decoys created during The Blitz to simulate burning British cities.[126] Starfish Prime was a high-altitude nuclear test conducted by the United States of America on 9 July 1962; the device exploded 250 miles (400 km) above the Pacific Ocean with a yield equivalent to 1.4 megatons of TNT.[127]

References

  1. ^ Sweet, Elizabeth (22 November 2005). "Asterozoa: Fossil groups: SciComms 05-06: Earth Sciences". Retrieved 7 May 2008. 
  2. ^ a b c d e f g h Knott, Emily (2004-10-07). "Asteroidea. Sea stars and starfishes". Tree of Life. Retrieved 2013-05-10. 
  3. ^ Mooi, Rich. "Classification of the Extant Echinodermata." California Academy of Sciences – Research.
  4. ^ a b c d Richard Fox. "Asterias forbesi". Invertebrate Anatomy OnLine. Lander University. Retrieved 2012-05-19. 
  5. ^ Anon (2013). "Introduction to Starfish". Animal Planet. Retrieved 2013-05-19. 
  6. ^ Daily Mail Reporter (2009-10-24). "You superstar! Fisherman hauls in starfish with eight legs instead of five". Daily Mail. Retrieved 2013-05-19. 
  7. ^ "Wonders of the Sea: Echinoderms." Ceanside Meadows Institute for the Arts and Sciences.
  8. ^ Walls, Jerry G. (1982). Encyclopedia of Marine Invertebrates. TFH Publications. pp. 681–684. ISBN 0-86622-141-7. 
  9. ^ a b c Dale, Jonathan (2000). "Starfish Digestion and Circulation". Madreporite Nexus. Retrieved 2012-10-18. 
  10. ^ a b c d Dorit, R. L.; Walker, W. F.; Barnes, R. D. (1991). Zoology. Saunders College Publishing. p. 782. ISBN 0-03-030504-7. 
  11. ^ McGraw-Hill Concise Encyclopedia of Bioscience. McGraw-Hill Professional. 2004. p. 790. ISBN 0071439560. 
  12. ^ a b Carefoot, Tom. "Predators & Defenses". Pedicellariae. A Snail Odyssey. Retrieved 2013-05-11. 
  13. ^ Ruppert, Edward E.; Fox, Richard, S.; Barnes, Robert D. (2004). Invertebrate Zoology, 7th edition. Cengage Learning. pp. 876–889. ISBN 81-315-0104-3. 
  14. ^ Barnes, R. S. K.; Callow, P.; Olive, P. J. W. (1988). The Invertebrates: a new synthesis. Oxford: Blackwell Scientific Publications. pp. 158–160. ISBN 0-632-03125-5. 
  15. ^ Chia, Fu-Shiang; Amerongen, Helen (1975). "On the prey-catching pedicellariae of a starfish, Stylasterias forreri (de Loriol)". Canadian Journal of Zoology 53 (6): 748–755. doi:10.1139/z75-089. 
  16. ^ O'Neill P. (1989). "Structure and mechanics of starfish body wall". Journal of Experimental Biology 147: 53–89. PMID 2614339. 
  17. ^ a b c Ruppert et al, 2004. p. 885
  18. ^ a b c d Ruppert et al, 2004. p.887
  19. ^ a b Ruppert et al, 2004. pp.879–883
  20. ^ Cavey, Michael; Wood, Richard (1981). "Specializations for excitation-contraction coupling in the podial retractor cells of the starfish Stylasterias forreri". Cell and Tissue Research 218 (3). doi:10.1007/BF00210108. 
  21. ^ Kerkut, G. A. (1953). "The Forces Exerted by the Tube Feet of the Starfish During Locomotion". Journal of Experimental Biology 30: 575–583. 
  22. ^ "Leather star - Dermasterias imbricata". Sea Stars of the Pacific Northwest. Retrieved 2012-09-27. 
  23. ^ "Sand star - Luidia foliolata". Sea Stars of the Pacific Northwest. Retrieved 2012-09-26. 
  24. ^ Dale, Jonathan (2001-11-09). "Chemosensory Orientation in Asterias forbesi". Madreporite Nexus. Retrieved 2013-05-15. 
  25. ^ Ruppert et al, 2004. pp. 883–884
  26. ^ a b Ruppert et al, 2004. pp. 863–864
  27. ^ Lawrence, John M. (ed.) (2013). "8". Chemistry and Ecological Role of Starfish Secondary Metabolites in "Starfish: Biology and Ecology of the Asteroidea". JHU Press. ISBN 1421410451. 
  28. ^ Zhang, Wen; Guo, Yue-Wei; Gu, Yucheng (2006). "Secondary Metabolites from the South China Sea Invertebrates: Chemistry and Biological Activity". Current Medicinal Chemistry 13 (17): 2041–2090. doi:10.2174/092986706777584960. 
  29. ^ a b c Byrne, Maria (2005). "Viviparity in the Sea Star Cryptasterina hystera (Asterinidae)--Conserved and Modified Features in Reproduction and Development". Biol Bull (Free full text) 208 (2): 81–91. doi:10.2307/3593116. PMID 15837957. 
  30. ^ Ottesen, P. O.; J. S. Lucas (1982). "Divide or broadcast: Interrelation of asexual and sexual reproduction in a population of the fissiparous hermaphroditic seastar Nepanthia belcheri (Asteroidea: Asterinidae)". Marine Biology 69 (3): 223–233. doi:10.1007/BF00397488. ISSN 0025-3162. 
  31. ^ a b c Crump, R.G; R. H. Emson (1983). "The natural history, life history and ecology of the two British species of Asterina". Field Stydies 5: 867–882. Retrieved 2011-07-27. 
  32. ^ a b McClary, D. J.; P. V. Mladenov (1989-12). "Reproductive pattern in the brooding and broadcasting sea star Pteraster militaris". Marine Biology 103 (4): 531–540. doi:10.1007/BF00399585. ISSN 0025-3162. 
  33. ^ a b Gordon Hendler and David R. Franz (1982). "The Biology of a Brooding Seastar, Leptasterias tenera, in Block Island" (Free full text). Biol Bull 162 (3): 273–289. doi:10.2307/1540983. JSTOR 1540983. 
  34. ^ Fu-Shiang Chia (1966). "Brooding Behavior of a Six-Rayed Starfish, Leptasterias hexactis" (Free full text). Biol Bull 130 (3): 304–315. doi:10.2307/1539738. JSTOR 1539738. 
  35. ^ Byrne, M. (1996). "Viviparity and intragonadal cannibalism in the diminutive sea stars Patiriella vivipara and P. parvivipara (family Asterinidae)". Marine Biology 125 (3): 551–567. ISSN 0025-3162. 
  36. ^ Ruppert et al, 2004. pp. 887–888
  37. ^ Strathmann, Richard R.; Strathmann Megumi F.; Emson, Roland H. (1984). "Does limited brood capacity link adult size, brooding, and simultaneous hermaphroditism? A test with the starfish Asterina phylactica". The American Naturalist 123 (6): 796–818. doi:10.1086/284240. ISSN 0003-0147. JSTOR 2460901. 
  38. ^ Run, J. -Q.; Chen, C. -P.; Chang, K. -H.; Chia, F. -S. (1988). "Mating behaviour and reproductive cycle of Archaster typicus (Echinodermata: Asteroidea)". Marine Biology 99 (2): 247–253. doi:10.1007/BF00391987. ISSN 0025-3162. 
  39. ^ Keesing, John K.; Fiona Graham, Tennille R. Irvine, Ryan Crossing (2011). "Synchronous aggregated pseudo-copulation of the sea star Archaster angulatus Müller & Troschel, 1842 (Echinodermata: Asteroidea) and its reproductive cycle in south-western Australia". Marine Biology 158 (5): 1163–1173. doi:10.1007/s00227-011-1638-2. ISSN 0025-3162. 
  40. ^ a b Miller, Richard L. (12 October 1989). "Evidence for the presence of sexual pheromones in free-spawning starfish". Journal of Experimental Marine Biology and Ecology 130 (3): 205–221. doi:10.1016/0022-0981(89)90164-0. ISSN 0022-0981. 
  41. ^ a b c d Ruppert et al, 2004. pp. 888–889
  42. ^ Fisher, W. K. (1925-03-01). "Asexual Reproduction in the Starfish, Sclerasterias". Biological Bulletin 48 (3): 171–175. doi:10.2307/1536659. ISSN 0006-3185. JSTOR 1536659. Retrieved 2011-07-15. 
  43. ^ a b c d Edmondson, C.H (1935). "Autonomy and regeneration of Hawaiian starfishes". Bishop Museum Occasional Papers 11 (8): 3–20. 
  44. ^ Monks, Sarah P. (1904-04-01). "Variability and Autotomy of Phataria". Proceedings of the Academy of Natural Sciences of Philadelphia (Free full text) 56 (2): 596–600. ISSN 0097-3157. JSTOR 4063000. 
  45. ^ Eaves, Alexandra A.; A. Richard Palmer (2003). "Reproduction: Widespread cloning in echinoderm larvae". Nature 425 (6954): 146. doi:10.1038/425146a. ISSN 0028-0836. 
  46. ^ Jaeckle, William B. (1994-02-01). "Multiple Modes of Asexual Reproduction by Tropical and Subtropical Sea Star Larvae: An Unusual Adaptation for Genet Dispersal and Survival" (Free full text). Biological Bulletin 186 (1): 62–71. doi:10.2307/1542036. ISSN 0006-3185. JSTOR 1542036. 
  47. ^ Vickery, M. S.; J. B. McClintock (2000-12-01). "Effects of Food Concentration and Availability on the Incidence of Cloning in Planktotrophic Larvae of the Sea Star Pisaster ochraceus". The Biological Bulletin 199 (3): 298–304. ISSN 1939-8697 0006-3185, 1939-8697. 
  48. ^ Knaack, Lauren; Jaeckel, William (2011). "Incidence of larval cloning in the sea urchins Arbacia punctulata and Lytechinus variegatus". John Wesley Powell Student Research Conference. Retrieved 2012-09-27. 
  49. ^ a b c McAlary, Florence A. (1993). "Population Structure and Reproduction of the Fissiparous Seastar, Linckia columbiae Gray, on Santa Catalina Island, California". 3rd California Islands Symposium. National Park Service. Retrieved 2012-04-15. 
  50. ^ Mladenov, Philip V; Suleiman Igdoura, Satish Asotra, Robert D Burke (1989-04-01). "Purification and Partial Characterization of an Autotomy-Promoting Factor from the Sea Star Pycnopodia Helianthoides". The Biological Bulletin 176 (2): 169–175. ISSN 1939-8697 0006-3185, 1939-8697. 
  51. ^ Hayashi, Yutaka; Tatsuo Motokawa (1986-09-01). "Effects of Ionic Environment on Viscosity of Catch Connective Tissue in Holothurian Body Wall". Journal of Experimental Biology 125 (1): 71–84. ISSN 1477-9145 0022-0949, 1477-9145. 
  52. ^ "Asteroidea (Sea Stars)". Encyclopedia.com. Grzimek's Animal Life Encyclopedia. 2004. Retrieved 2012-07-14. 
  53. ^ Dale, J. "Starfish Ecology". Madreporite Nexus. Retrieved 2009-05-24. 
  54. ^ Nybakken Marine Biology: An Ecological Approach, Fourth Edition, page 174. Addison-Wesley Educational Publishers Inc., 1997.
  55. ^ Menage, B. A.; Sanford, E. "Ecological Role of Sea Stars from Populations to Meta-ecosystems". p. 67.  in Lawrence (2013)
  56. ^ Wagner, S. C. (2012). "Keystone Species". Nature Education Knowledge. Retrieved 2013-05-16. 
  57. ^ Paine, R. T. (1966). "Food web complexity and species diversity". American Naturalist 100 (190): 65–75. JSTOR 2459379. 
  58. ^ Paine, R. T. (1971). "A short-term experimental investigation of resource partitioning in a New Zealand rocky intertidal habitat". Ecology 52 (6): 1096–1106. JSTOR 1933819. 
  59. ^ Scheibling, R. E. (1980). "Dynamics and feeding activity of high-density aggregations of Oreaster reticulatus (Echonodermata: Asteroidea) in a sand patch habitat". Marine Ecology Progress Series 2: 321–27. 
  60. ^ Birkeland, C. (1982). "Terrestrial runoff as a cause of outbreaks of Acanthaster planci (Echinodermata: Asteroidea)". Marine Biology 69 (2): 175–85. doi:10.1007/BF00396897. 
  61. ^ a b Kayal Mohsen, Vercelloni, J.; Lison de Loma, T.; Bosserelle, P.; Chancerelle, Y.; Geoffroy, S.; Stievenart, C.; Michonneau, F.; Penin, L.; Planes, S. (2012). "Predator crown-of-thorns starfish (Acanthaster planci) outbreak, mass mortality of corals, and cascading effects on reef fish and benthic communities". PLoS ONE 7 (10): e47363. doi:10.1371/journal.pone.0047363. 
  62. ^ a b Byrne, M.; O'Hara, T. D.; Lawrence, J. M. "Asterias amurensis". pp. 177–79.  in Lawrence (2013)
  63. ^ "100 of the World's Worst Invasive Alien Species". Global Invasive Species Database. Retrieved 2010-07-16. 
  64. ^ Gaymer, C. F.; Himmelman, J. H. "Leptasterias polaris". p. 184.  in Lawrence (2013)
  65. ^ a b Robles, C. "Pisaster ochraceus". pp. 166–67.  in Lawrence (2013)
  66. ^ Scheibling, R. E. "Oreaster reticulatus". p. 150.  in Lawrence (2013)
  67. ^ Shedd, John G. (2001–2006). "Crown of Thorns Sea Star". Shedd Aquarium. Retrieved 2013-05-22. 
  68. ^ Peters, L. E.; Mouchka M. E.; Milston-Clements, R. H.; Momoda, T. S.; Menge B. A. (2008). "Effects of environmental stress on intertidal mussels and their sea star predators". Oecologia 156 (3): 671–80. doi:10.1007/s00442-008-1018-x. PMID 18347815. 
  69. ^ Pincebourde, S.; Sanford, E.; Helmuth, B. (2008). "Body temperature during low tide alters the feeding performance of a top intertidal predator". Limnology and Oceanography 53 (4): 1562–73. 
  70. ^ Pincebourde, S.; Sanford, E.; Helmuth, B. (2009). "An intertidal sea star adjusts thermal inertia to avoid extreme body temperatures". The American Naturalist 174 (6): 890–897. JSTOR 10.1086/648065. 
  71. ^ Mah, Christopher (2009-09-06). "The Invisible Loss: The Impacts of Oil You Do Not See". The Ocean Portal. Smithsonian Institution. Retrieved 2012-10-18. 
  72. ^ Gooding, R.; Harley, C.; Tang, E. (2009). "Elevated water temperature and carbon dioxide concentration increase the growth of a keystone echinoderm". Proceedings of the National Academy of Sciences 106 (23): 9316–21. doi:10.1073/pnas.0811143106. PMC 2695056. PMID 19470464. 
  73. ^ Wray, Gregory A. (1999). "Echinodermata: Spiny-skinned animals: sea urchins, starfish, and their allies". Tree of Life web project. Retrieved 2012-10-19. 
  74. ^ a b Knott, Emily (2004). "Asteroidea: Sea stars and starfishes". Tree of Life web project. Retrieved 2012-10-19. 
  75. ^ Stöhr, S.; O’Hara, T. "World Ophiuroidea Database". Retrieved 2012-10-19. 
  76. ^ Purit, J. B.; Keever, C. C.; Addison, J. A.; Byrne, M.; Hart, M. W.; Grosberg, R. K.; Toonen, R. J. (2012). "Extraordinarily rapid life-history divergence between Cryptasterina sea star species". Proceedings of the Royal Society B: Biological Sciences 279 (1744): 3914–22. doi:10.1098/rspb.2012.1343. 
  77. ^ Mah, Christopher (2012). "Brisingida". World Register of Marine Species. Retrieved 2012-09-15. 
  78. ^ Downey, Maureen E. (1986). "Revision of the Atlantic Brisingida (Echinodermata: Asteroidea), with Description of a New Genus and Family". Smithsonian Contributions to Zoology: 435. Smithsonian Institution Press. Retrieved 2012-10-18. 
  79. ^ "Brisingida". Access Science: Encyclopedia. McGraw-Hill. Retrieved 2012-09-15. 
  80. ^ a b c Vickery, Minako S.; McClintock, James B. (2000). "Comparative Morphology of Tube Feet Among the Asteroidea: Phylogenetic Implications". Integrative and Comparative Biology 40 (3): 355–364. doi:10.1093/icb/40.3.355. 
  81. ^ Mah, Christopher (2012). "Forcipulatida". World Register of Marine Species. Retrieved 2012-09-15. 
  82. ^ a b Barnes, Robert D. (1982). Invertebrate Zoology. Philadelphia, PA: Holt-Saunders International. p. 948. ISBN 0-03-056747-5. 
  83. ^ Mah, Christopher. "Forcipulatida". Access Science: Encyclopedia. McGraw-Hill. Retrieved 2012-09-15. 
  84. ^ Mah, Christopher (2012). "Notomyotida". World Register of Marine Species. Retrieved 2012-09-15. 
  85. ^ "Asterozoa: Fossil groups: SciComms 05-06: Earth Sciences". Palaeo.gly.bris.ac.uk. 2005-11-22. Retrieved 2010-09-15. 
  86. ^ Mah, Christopher (2012). "Paxillosida". World Register of Marine Species. Retrieved 2012-09-15. 
  87. ^ Matsubara, M.; Komatsu, M.; Araki, T.; Asakawa, S.; Yokobori, S.-I.; Watanabe, K.; Wada, H. (2005) The phylogenetic status of Paxillosida (Asteroidea) based on complete mitochondrial DNA sequences. Molecular Genetics and Evolution, 36, 598–605
  88. ^ Mah, Christopher (2012). "Spinulosida". World Register of Marine Species. Retrieved 2012-09-15. 
  89. ^ "Spinulosida". Access Science: Encyclopedia. McGraw-Hill. Retrieved 2012-09-15. 
  90. ^ a b Blake, Daniel B. (1981). "A reassessment of the sea-star orders Valvatida and Spinulosida". Journal of Natural History 15 (3): 375–394. doi:10.1080/00222938100770291. 
  91. ^ Mah, Christopher (2012). "Valvatida". World Register of Marine Species. Retrieved 2012-09-15. 
  92. ^ Mah, Christopher (2012). "Velatida". World Register of Marine Species. Retrieved 2012-09-15. 
  93. ^ Mah, Christopher. "Velatida". Access Science: Encyclopedia. McGraw-Hill. Retrieved 2012-09-15. 
  94. ^ Schöndorf, F. (1910). "Die Asteriden der deutschen Trias (in German)". Jahresbericht des Niedersächsischen Geologische Vereins 3: 90–116. 
  95. ^ "Family Calliasterellidae". Paleobiology Database. Retrieved 2013-05-10. 
  96. ^ Gale, A. S. (1987). "Phylogeny and classification of the Asteroidea (Echinodermata)". Zoological Journal of the Linnean Society 89: 107–132. 
  97. ^ Blake, D. B. (1987). "A classification and phylogeny of post-Paleozoic sea stars (Asteroidea: Echinodermata)". Journal of Natural History 21: 481–528. 
  98. ^ a b c Janies, Daniel A.; Voight, Janet R.; Daly, Marymegan (2011). "Echinoderm Phylogeny Including Xyloplax, a Progenetic Asteroid". Syst. Biol. 60 (4): 420–438. doi:10.1093/sysbio/syr044. 
  99. ^ "William Jenkyn Thomas, M.A.". The Aberdare Boys’ Grammar School. Retrieved 2013-05-12. 
  100. ^ Thomas, William Jenkyn (1943). Some Myths and Legends of the Australian Aborigines. Whitcombe & Tombs. pp. 21–28. 
  101. ^ a b c Tregear, Edward (March 1900). ""The Creation Song" of Hawaii". The Journal of the Polynesian Society 9 (1): 38–46. 
  102. ^ a b Rumphius, Georgious Everhardus (= Georg Eberhard Rumpf); Beekman, E.M. (trans.) (1999, first published 1705). The Ambonese Curiosity Cabinet (original title: Amboinsche Rariteitkamer). Yale University Press. p. 68. ISBN 978-0-300-07534-2. 
  103. ^ Watts, Peter (2008). Starfish (Rifters Trilogy). Tor. 
  104. ^ Orbell, Jennie (2012). Starfish. Tedge Press. 
  105. ^ Addison, Alice (2012). Starfish - a year in the life of bereavement and depression. Chipmunkapublishing. 
  106. ^ Brafman, Ori; Beckstrom, Rod (2006). The Starfish and the Spider: The Unstoppable Power of Leaderless Organizations. Penguin. 
  107. ^ Andersson, L.; Bohlin, L; Iorizzi, M; Riccio, R; Minale, L; Moreno-López, W. (1989). "Biological activity of saponins and saponin-like compounds from starfish and brittle-stars.". Toxicon 27 (2): 179–188. 
  108. ^ Lin, S. J.; Hwang, D. F. (April 2001). "Possible source of tetrodotoxin in the starfish Astropecten scoparius.". Toxicon 39 (4): 573–579. 
  109. ^ Asakawa M.; Nishimura F.; Miyazawa K.; Noguchi T. (1997). "Occurrence of paralytic shellfish poison in the starfish Asterias amurensis in Kure Bay, Hiroshima Prefecture, Japan". Toxicon 35 (7). pp. 1081–1087. 
  110. ^ Amakusa TV Co. Ltd. (2011-08-07). "Cooking Starfish in japan". ebook10005. Amakusa TV. Retrieved 2013-05-18. 
  111. ^ "Pouch". Kenko.com. Retrieved 2013-05-18. 
  112. ^ Lurie, R. D. (2009). No Certainty Attached: Steve Kilbey and the Church. Portland, Oregon: Verse Chorus Press. p. 197. 
  113. ^ "Carlos and Veronica" (2009). "A Gift from a Flower to a Garden". Donovan Unofficial. Retrieved 2013-05-09. 
  114. ^ Leitch, Donovan. "Starfish-on-the-Toast Lyrics". Sing365. Retrieved 2013-05-09. 
  115. ^ "SpongeBob SquarePants". Patrick. Nickelodeon. 2013. Retrieved 2013-05-16. 
  116. ^ Bradshaw, Peter (2006-06-23). "Aquamarine". The Guardian. Retrieved 2013-05-09. 
  117. ^ "Aquamarine: Cast & Details". TVguide.com. Retrieved 2013-05-09. 
  118. ^ "http://larvalabs.com/starfish". Larva Labs. 
  119. ^ Starfish Associates LLC (2005–2013). "Starfish". Starfish Associates. Retrieved 2013-05-10. 
  120. ^ "Motorola to Acquire Starfish". Motorola. 1998-07-14. Retrieved 2013-05-11.  (See also Starfish Software.)
  121. ^ "Starfish". Duke Startup Challenge. Retrieved 2013-05-10. 
  122. ^ "Starfish". Starfish Seabed Imaging Systems. 2013. Retrieved 2013-05-10. 
  123. ^ Manning, T.D. (Captain) (1961). The British Destroyer. Godfrey Cave Associates. ISBN 0-906223-13-X. 
  124. ^ "H.M.S. Starfish (1916)". Dreadnought Project. 2012. Retrieved 2013-05-11. 
  125. ^ Helgason, Guðmundur (1995–2013). "HMS Starfish (19 S)". Uboat.net. Retrieved 2013-05-11. 
  126. ^ Crowdy, Terry (2008). Deceiving Hitler: double cross and deception in World War II. Osprey Publishing. p. 61. ISBN 1-84603-135-4. 
  127. ^ Dyal, P. (1965-12-10). "Operation Dominic. Fish Bowl Series. Debris Expansion Experiment". Report ADA995428. Air Force Weapons Laboratory. Retrieved 2013-05-11. 

Bibliography

  • Lawrence, J. M., ed. (2013). Starfish: Biology and Ecology of the Asteroidea. Johns Hopkins University Press. ISBN 978-1-4214-0787-6. 
  • Ruppert, Edward E.; Fox, Richard, S.; Barnes, Robert D. (2004). Invertebrate Zoology, 7th edition. Cengage Learning. ISBN 81-315-0104-3. 

Further reading

Books
  • Gilbertson, Lance. Zoology Lab Manual; McGraw Hill, New York; (fourth edition, 1999). ISBN 0-07-237716-X.
  • Hickman C.P; Roberts L.S; Larson A.; l'Anson H.; Eisenhour D.J. Integrated Principles of Zoology; McGraw Hill; New York; (thirteenth edition, 2006). ISBN 0-07-111593-5.
  • Solomon, E.P.; Berg, L.R.; Martin, D.W. Biology, (ninth edition, 2002). ISBN 978-0-538-74143-9.
Papers
  • Blake D.B.; Guensburg T.E. Implications of a new early Ordovician asteroid (Echinodermata) for the phylogeny of Asterozoans; Journal of Paleontology, 79 (2): 395–399; March 2005.
  • Shackleton, Juliette D. Skeletal homologies, phylogeny and classification of the earliest asterozoan echinoderms; Journal of Systematic Palaeontology; 3 (1): 29–114; March 2005.
  • Sutton M.D.; Briggs D.E.G.; Siveter D.J.; Gladwell D.J. A starfish with three-dimensionally preserved soft parts from the Silurian of England; Proceedings of the Royal Society B – Biological Sciences; 272 (1567): 1001–1006; May 22, 2005.
Wikimedia Commons has media related to: Starfish
Retrieved from "http://en.wikipedia.org/w/index.php?title=Starfish&oldid=556628775"