The green anaconda, Eunectes murinus, also known as the common anaconda or water boa, is a species of snake in South America, being the largest snake in the world. In the wild, a 10 to 12 meters anaconda that weighs more than 250 kg has been discovered, although the actual maximum size of an anaconda is the subject of many controversies. Females typically have a much larger weight and length than males, reaching an average length of 6 meters while males will only reach 6 meters in length. The gender of an anaconda is reflected by the size of the spurs located in the cloacal region. Males have larger notches, at around 7,5 millimeters than females.
The scientific name of green anaconda is derived from the Greek term eленic, meaning “good swimmer”.
The green anaconda is one of the four constrictor species, the other species being Eunectes notaeus, the yellow anaconda, Eunectes deschauenseei, the dark anaconda, and Eunectes beniensis, the Bolivian anaconda.
The green anaconda became famous in the human world with its discovery and description in the scientific world in 1758 by the renowned Swedish naturalist Carl Linnaeus. Because it is the largest representative of the boa family, Venezuelan and Brazilian farmers call it green boa because of its color, or water boa, with direct reference to the aquatic environment in which this giant with scales lives. The Indians of the South American tribes call it Sucurinju, Yakumama, or Jiboia.
Like all snakes, the anaconda has a forked tongue that helps it locate the prey and move around in its environment.
The green anaconda is more active in the evening. It can travel long distances and in short periods of time, especially in the dry annual seasons. They migrate preferentially after the peak heat of the day. Anacondas are able to regulate their body temperature.
Eunectes murinus is found in South America to the east of the Andes, in countries such as Colombia, Venezuela, Guiana, Ecuador, Peru, Bolivia, Brazil, the island of Trinidad, and northern Paraguay. Anaconda lives in swamps, mainly in the rainforests of the Amazon and Orinoco basins. It is heavy on land, but it swims easily. The eyes and nasal openings lie on the head, allowing it to sit in wait for the prey, remaining almost completely submerged.
Basically aquatic, it consumes a wide variety of prey, including fish, birds, a variety of mammals, and other reptiles. Being particularly large, it can also consume large prey such as tapirs, deer, capybaras, caimans, and even jaguars, but such food is not consumed regularly. They use constriction to subdue their prey.
Cannibalism among green anacondas is also known, with most recorded cases involving a larger female consuming a smaller male.
Anaconda stalks its prey while standing in the swamps and ponds from the endless amazon selva, usually avoiding the rapid streams of water. From its hiding place, the anaconda lies motionless for hours until the prey reaches its attack range. The attack happens lightning-fast as the huge snake puts down its prey. The prey is snatched with a multitude of teeth, after which, if the victim is small, it will be carried in the water and drowned.
If it has caught a large prey, the anaconda’s body wraps around the victim, after which the terrible clasp of force follows. Ring by ring, millimeter by millimeter, the snake begins to tighten its muscles until the prey is suffocated and eventually takes its last breath.
In very rare cases, when the anaconda feels that it is in great danger, it regurgitates the prey, which may be twice as large as its size, to get rid of the predators around it.
Anaconda mating is an interesting phenomenon, unique in the world of reptiles. During the mating season, the female eliminates a specific smell that attracts all males in the territory crossed by it, like a magnet. The males gather in a real “mating ball” in which about 12-15 males wreathe around the female.
Mating may take several weeks. During this time, a female can mate with several males. Males compete to gain access to the female by wrapping around it.
Females are selective in the mating process. In conditions of high density or when females are easy to follow, males can meet, which can lead to confrontations between them. However, male fights are rare.
Females are ovoviviparous and incubate their eggs for up to 7 months until they give birth to live offspring. Feeding movements and behaviors are limited to avoid compromising their health. Females give birth in shallow water, in the evening or late afternoon, at the end of the wet season. They can give birth to 82 offspring. Newborns measure 60 cm on average and do not need parental care. At the age of 4 years, young anaconda females reach reproduction maturity.
Possible threats to this species include habitat loss and exotic pet trade. Anacondas are listed as vulnerable species in CITES, but information about them is relatively rare. The Venezuelan Fisheries and Wildlife Service, the Wildlife Conservation Society, and the Convention on International Trade in Endangered species (CITES) funded the Green Anaconda project for us to understand the potential threats to the species.