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Eunectes murinus

Common names: anaconda, common anaconda, water boa, green anaconda.

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.

Description

There is some debate regarding the maximum size of this species. Mehrtens (1987) states that the average adult length is , with specimens being very rare. He sets a more conservative maximum at . Estimates of are based on vague data and should be regarded with caution. In a study of 1,000 specimens captured in Venezuela, the largest was long and weighed . 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 large cash reward (currently worth US$50,000) for live delivery of any snake of or more in length. This prize has never been claimed. 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 plus snake showed a variation of more than 20% in their results.

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.

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."

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.

Reproduction

Anacondas are solitary animals until mating. During the mating season (corresponding to the rainy season) males must find the females, and while it is still unclear how they track a female's scent, many males often go after the same female. This in turn results in odd clusters colloquially called "breeding balls" in which up to 12 males wrap around the same female attempting to copulate. Copulation takes place in the water, with gestation lasting approximately 6 months. Anacondas are ovoviviparous, meaning that they produce eggs which hatch inside the mother's body and result in live births. The newborn, which usually number 20-30, are around 60 centimetres in size and receive no parental care. Should they survive, they reach sexual maturity in about 3 to 4 years.

Captivity

In captivity, these snakes are known for their aggressive disposition.

Subspecies

Subspecies	Taxon author	Common name	Geographic range
E. m. gigas	(Latreille, 1801)
E. m. murinus	(Linnaeus, 1758)	Green anaconda

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. In the 2006 production Snakes on a Plane, the snake that drops from the ceiling is in reality not E. murinus rather a Burmese Python (Python molurus bivittatus) named Kitty. 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.