Green anaconda
| Green anaconda | |
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| Species: | E. murinus
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| Binomial name | |
| Eunectes murinus (Linnaeus, 1758)
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Eunectes murinus is a non-venomous boa species found in South America. It is known as one of the largest of all snakes. Two subspecies are currently recognized, including the nominate subspecies described here.[4]
Description
There is some debate regarding the maximum size of this species. Mehrtens (1987) states that the average adult length is 18 to 20 feet (5.5–6.1 m), with Template:Ft to m specimens being very rare. He sets a more conservative maximum at Template:Ft to m. Estimates of 35 to 40 feet (11–12 m) are based on vague data and should be regarded with caution.[2] In a study of 1,000 specimens captured in Venezuela, the largest was 17 feet (5.2 m) long and weighed 100 pounds (45 kg).[5] Females are significantly longer than males, having the most conspicuous sexual dimorphism of all snakes.
The Wildlife Conservation Society has, since the early 20th century, offered a cash reward (currently worth US$50,000) for live delivery of any snake of Template:Ft to m or more in length. This prize has never been claimed.[6] In any case, measuring a snake that is stronger than the person is not an easy task. It was found that two scientists independently measuring the same 12-foot (3.7 m) plus snake showed a variation of more than 20% in their results.[7]
The color pattern consists of olive green ground color overlaid with black blotches that run the length of the body. The head is narrow compared to the rest of the body, usually with distinctive orange-yellow striping on either side. The eyes are set high on the head and allow the snake to see out of the water when swimming without exposing its body.
Common names
Anaconda, common anaconda, water boa,[2] green anaconda.[3]
Local names in South America include the Spanish term "matatoro," meaning "bull killer," and the Native American terms sucuri and "yakumama" in the Peruvian region of the Amazon, which means "mother of the water" in the language of the Amazonian Yakurunas or "water people".
Geographic range
Found in South America in countries east of the Andes, including Colombia, Venezuela, the Guianas, Ecuador, Peru, Bolivia, Brazil and on the island of Trinidad. The type locality given is "America."[1]
Behavior
The primarily nocturnal anaconda species tend to spend most of its life in or around water. Anacondas are also sometimes known as the "Water Boa;" they spend more time in water than any of the boas. Because of its size being typically large it appears to be rather slow and sluggish when traveling on land. Completely the opposite in water however, anacondas are known to have the potential to reach incredibly high speeds in all depths of water levels. One tends to float atop the surface of the water with its snout barely poking out above the surface. When prey simply passes by or stops to drink, the hungry anaconda will snatch it using its jaws (without eating or swallowing it) and coils around it with its body. The snake will then constrict, tighten, and squeeze its coils until the anaconda has successfully suffocated and/or drowned its victim. Prey is suffocated, but never "crushed." The anaconda tightens only enough to stop its victim's breathing.[8]
Feeding
Primarily aquatic, they eat a wide variety of prey, almost anything they can manage to overpower, including fish, birds, a variety of mammals, and other reptiles. Particularly large anacondas may even consume large prey such as tapir, deer, capybara, caiman, and sometimes crocodiles and jaguars, but such large meals are not regularly consumed. In addition, there have been many reports and documentaries on anacondas consuming humans.They employ constriction to subdue their prey. Cannibalism among green anacondas is also known, most recorded cases involving a larger female consuming a smaller male. Scientists cite several possible reasons for this, including the dramatic sexual dimorphism in the species and the possibility that female anacondas require additional food intake after breeding to sustain their long gestation period and the male simply being an opportunistic prey item, but the exact reason is not understood.[9]
Reproduction
This species is solitary until the mating season, which corresponds to the rainy season, can last for several months, and usually takes place from April to May. During this time, males must find females. Typically, female snakes will lay down a trail of pheromones for the males to follow, but it is still unclear how the males of this species track a female's scent. Another possibility is that the female releases an air-borne stimulant. This theory is supported by the observation of females that remain motionless while many males move towards them from all directions. The male anacondas also frequently lick the air to sense chemicals that signal the presence of the female.[citation needed]
In any case, many males often find the same female. Although it may not be necessary for there to be more than one male, this results in odd clusters, referred to as "breeding balls," in which up to 12 males wrap around the same female and attempt to copulate. The group could stay in this position from two to four weeks. This ball acts as a slow-motion wrestling match between the males; each one fighting for the right to mate with the female.
During mating, males make use of their spurs to arouse the female. They aggressively press their cloacal regions hard against the female body while continuously scratching her with their spurs. This can produce a scratching sound. Mating approaches its climax when the stimulus of the males' spurs induce the female snake to raise her cloacal region, allowing the cloacae of the two snakes to move together. The male then coils his tail, surrounding the female and they copulate.[citation needed] The strongest and largest male is often the victor. However, females are physically much larger and stronger and may decide to choose from among the males. Courtship and mating occur almost exclusively in water.
Mating is followed by a gestation period that lasts approximately 6 months. The species is ovoviviparous, with females giving birth to live young. Litters usually consists of 20-40 offspring, although as many as 100 may be produced. After giving birth, females may lose up to half their weight.
Neonates are around 70-80 cm long and receive no parental care. Because of their small size, they often fall prey to other animals. Should they survive, they grow rapidly until they reach sexual maturity in their first few years, after which their rate of growth continues at a slower pace.[10]
Captivity
Anacondas, like other snakes and most other reptiles, can quite easily adapt to a change in the climate, environment, and near surroundings when necessary. The reasons for an anaconda's needing to adapt can vary. They may need to adapt to adjust to changes in the availability of food, and any diseases they may be exposed to in new surroundings. An anaconda might also have to adjust to changes in temperature and humidity. Changes in temperature could drastically affect the snake because it is ectothermal, and relies on its environment to control its temperature. If the temperature of its surroundings increases, a snake will do everything possible to prevent its body from over-heating, and if it decreases, it will attempt to lie in heated areas to help maintain its normal temperature. Anacondas, like all other snakes, control and regulate their body temperatures by changing the amount of surface of their skin that is exposed to the sun. If the terrarium, location or "tank" where a reptile is kept, is uniformly heated producing what is known as "the greenhouse effect", then the snake could possibly die from over-heating (hyperthermia). The humidity of its surroundings might also be slightly different than the humidity to which the snake was previously accustomed. This could, potentially, drastically alter its shedding cycle. The obstruction of this cycle is extremely dangerous. The hindrance of an anaconda's shedding cycle most often causes retention of eye caps.[11] Due to these conditions and emotions of the snake, anacondas are known for their aggressive disposition when being held in captivity.[12]
Environmental requirements
One may reasonably maintain an average and acceptable temperature for the snake by the use of a simple heater and infrared light bulbs. Anacondas and other snakes must be exposed to ultraviolet(UV) radiation. This is exceptionally significant because the snake needs it to produce vitamin D3 for further bone development in its body. Occasional exposure to light bulbs that emit UV radiation with proper wavelength, or better yet, the sun, is also necessary to maintain the positive health of an anaconda. Optimum humidity can be difficult to maintain and research must be done on the snake to determine the correct level. A percentage of just less than 80% humidity must be maintained for caging an anaconda species from the tropical region, while a slightly less than 30% humidity must be maintained for a species of a desert region.[13]
Subspecies
| Subspecies[4] | Taxon author[4] | Common name | Geographic range |
|---|---|---|---|
| E. m. gigas | (Latreille, 1801) | ||
| E. m. murinus | (Linnaeus, 1758) |
Entertainment
These snakes are among the most dramatized and most terrifying of villains portrayed in natural horror films, supposedly growing to over 120 feet in length and able to swallow adult humans; traits that are occasionally also attributed to other species, such as the Burmese python and the boa constrictor. Among the most popular snake films that feature it are the 1997 film, Anaconda, along with its two sequels Anacondas: The Hunt for the Blood Orchid and Anaconda 3: The Offspring. This species is also the main antagonist in Mathias Bradley's novel, Anacondas: The Terror of the Amazon Rainforest, in which multiple hybrid anacondas escape from a research facility in the Amazon Rainforest and come into contact with a toxic chemical that causes them to rapidly mutate into gigantic snakes.
See also
References
- ^ a b McDiarmid RW, Campbell JA, Touré T. 1999. Snake Species of the World: A Taxonomic and Geographic Reference, vol. 1. Herpetologists' League. 511 pp. ISBN 1-893777-00-6 (series). ISBN 1-893777-01-4 (volume).
- ^ a b c Mehrtens JM. 1987. Living Snakes of the World in Color. New York: Sterling Publishers. 480 pp. ISBN 0-8069-6460-X.
- ^ a b Eunectes murinus at the Reptarium.cz Reptile Database. Accessed 4 July 2008.
- ^ a b c "Eunectes murinus". Integrated Taxonomic Information System. 3 July.
{{cite web}}: Check date values in:|date=and|year=/|date=mismatch (help) - ^ The Search for the $50,000 Snake at MSN Encarta. Accessed 18 July 2008.
- ^ Splendor in the Mud: Unraveling the Lives of Anacondas by Carol Kaesuk Yoon, April 2 1996, at New York Times. Accessed 18 July 2008.
- ^ Rivas JA, Ascanio RE, Muñoz MDC. 2008. What is the length of a snake? Comtemporary Herpetology, Vol. 2008(2):1-3. PDF at Comtemporary Herpetology. Accessed 18 July 2008.
- ^ Soomro, Adil (April 2001). "Animal Diversity Web". University of Michigan Museum of Zoology. University of Michigan Museum of Zoology. Retrieved 2008-11-12.
- ^ Eunectes murinus (Green Anaconda): Cannibalism at Prodigy. Accessed 3 July 2008.
- ^ Soomro, Adil (2001). "Eunectes murinus". The University of Michigan Museum of Zoology. Animal Diversity Web. Retrieved 2008-10-10.
{{cite news}}: Cite has empty unknown parameter:|coauthors=(help) - ^ E. Fowler, Murray (2001). Biology, Medicine, and Surgery of South American Wild Animals. Blackwell Publishing. pp. 40–41. ISBN 0813828465.
{{cite book}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ LLLReptile: Green Anaconda Captive Care at LLLReptile. Accessed 3 July 2008.
- ^ E. Fowler, Murray (2001). Biology, Medicine, and Surgery of South American Wild Animals. Blackwell Publishing. pp. 40–41. ISBN 0813828465.
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Further reading
- Dirksen L, Böhme W. 1998. Studien an Anakondas 2: Zum taxonomischen Status von Eunectes murinus gigas (Latreille, 1801) (Serpentes: Boidae), mit neuen Ergebnissen zur Gattung Eunectes Wagler, 1830.- Salamandra 34(4): 359-374.
- Dirksen L. 2002. Anakondas. Monographische Revision der Gattung Eunectes (Wagler, 1830).- Natur und Tier-Verlag Münster. ISBN 3-931587-43-6. 187 pp.
External links
- Eunectes murinus (Green anaconda): Cannibalism at prodigy.net. Accessed 1 December 2008.
- Anacondas.org. Accessed 1 December 2008.