Anaconda, Green


Eunectes murinus  


Dark green in color (hence the name Green Anaconda) with alternating oval black spots; similar spots with yellow-ochre centers are along the sides of its body; head is large and narrow and is not distinct from the thick neck area. Eyes and nostrils are set on the top of the head.  Body is exceptionally stocky compared to other boas and extremely muscular; covered with scales with spurs, small claw like appendages, on either side of the cloaca. The only area without scales is the cloaca. This area contains glands that emit a foul smelling toffee colored musk.  This species is a constrictor and not venomous. Adults of this species reach average lengths of 18 – 20 ft.  Extreme lengths in excess of 29 ft have not been scientifically documented.  Adults may weigh up to 440 lbs. (200 kg).

Family

Boidae

Order

Squamata Suborder: Serpentes

Class

Reptilia

Range

South America countries east of the Andes, including Colombia, Venezuela, the Guianas, Ecuador, Peru, Bolivia, Brazil and on the island of Trinidad

Habitat

Sluggish or still waters rather than clear, swift flowing streams; they are found at relatively low altitudes and can often be found in the shallow caves beneath the undercut banks.

Life Expectancy

In the wild, an average of 10 years; in captivity, they may reach 30 years of age.

Sexual Maturity

Diet

In the wild, they eat fish, birds, mammals and other reptiles; in the Zoo, they are fed rabbits.

Status

CITES – Appendix II

Behaviors

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 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 constricts, tightens, and squeezes 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. 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. 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. This species is solitary until the mating season, which corresponds to the rainy season, which 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. Male anacondas also frequently lick the air to sense chemicals that signal the presence of the female. 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 induces the female snake to raise her cloacal region, allowing the cloacae of the two snakes to move together. The male then coils his tail around the female and they copulate. 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 27.6 – 31.5 in (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.

Adaptions

The foul smelling toffee colored musk, which is poisonous for small organisms, may prevent ticks and leeches from attaching themselves to the cloaca.

Special Interests

A group of anacondas is called a “bed” or “knot” of anacondas. The green anaconda shows the greatest sexual dimorphism in terms of size of all the snakes. Adult females usually attain lengths of 18-20 feet. Males generally grow to a maximum of 10-12 feet.

Folklore

Local names in South America include the Spanish term “matatoro,” meaning “bull killer.” A Tupi term widely used in Portuguese, sucuri, is the common name for the anaconda throughout Brazil. In the Peruvian region of the Amazon, the Yakurunas (“water people”) call the anaconda yakumama, or “mother of the water.” Although the name “anaconda” is said to have derived from the Tamil word “anaikolra”, which stands for “elephant killer”, major English dictionaries like Oxford English Dictionary, American Heritage Dictionary, and Merriam-Webster Collegiate Dictionary, do not conclusively attribute anaconda to a Tamil word origin. Instead, these dictionaries give origin credit to the Sinhalese henakandaya, which means “whipsnake”. There are many local stories and legends regarding the anaconda as a man-eater, but there is very little evidence to support any such activity. The shoulders of humans are far too wide for even an exceptionally large anaconda to swallow, and although they are capable of fatal constriction on humans, this also appears to be very rare and there is no record of a wild anaconda killing a human. It appears that the anaconda’s notorious reputation as a ruthless man-eater is nothing more than mythology and a product of Hollywood fiction.

Conservation

Currently all trade in anacondas is prohibited in most South American countries; however, some have annual quotas and periodically export live snakes for zoos, research and the pet trade. Few people however take anacondas as pets due to their large size and aggressive nature. Some skins are traded illegally; however, this is not having a significant impact on anaconda populations as they are hard to catch and their dark scaly skin does not translate well into flashy belts, shoes and purses. The large size of the Green Anaconda leaves very few natural predators. Its greatest threat is man. Incidental killing is perhaps the greatest threat to anacondas. Most people who live near these snakes are afraid of them and routinely kill them on sight. This is largely due in part to the lack of knowledge about them and because of reliance on myths and stories depicting anacondas as man-eaters. Habitat destruction is yet another cause for the decline in anaconda populations. At present, little is known about the anaconda. The Venezuelan Wildlife Department (PROFAUNA), the Convention on International Trade in Endangered Species of Flora and Fauna (CITES) and the Wildlife Conservation Society in a joint effort are conducting the first field study ever done on the Green Anaconda (Eunectes murinus). The main purpose of this study will enable wildlife officials to decide whether or not a conservation program based on commercial harvesting will be viable.

Jacksonville Zoo History

Historically, the Jacksonville Zoo has exhibited both the green and yellow anaconda species. Green anacondas have been part of our collection off and on since about 1965.

Exhibit

Range of the Jaguar