Green anacondas are infamous as the world’s largest and heaviest variety of snake. They do not hold the claim to being the longest snake though with this title going to the reticulated python. They have grown to be 8.8m (29ft) long and 250kg (550lbs) in weight. Their diameter may be as much as 30.5cm (12in). Females are much smaller than males.
They have an olive green coloured skin spotted with black blotches. Their narrow head has an orange-yellow stripe running down the side. When swimming they are able to see without putting their body above the water due to their high set highs.
Anacondas are a carnivorous species. This one feeds upon anything which it can overpower. This can range from birds, mammals, reptiles and fish through to larger prey like tapirs, capybara, deer and caimans. It is rare that such a large prey item is eaten.
In some cases cannibalism has been observed with females eating smaller males. Scientists suggest that this may be an opportunistic move after birth to meet their food needs for the long gestation period.
To kill their prey they will constrict them using their muscular body. Often the prey is dragged into the water which is believed to help them maneuver their food into the correct position. Once a large meal has been eaten it may be months before they eat once again.
Wild 10 years
Captive 30 years
Green anacondas roam throughout the South American countries of Colombia, the Guianas, Ecuador, Peru, Bolivia, Brazil and Paraguay. They are also present on the island of Trinidad.
They live in slow-moving freshwater areas which are quite shallow. These are located in tropical savannas, grasslands and rainforests. They can also be found in swamps and marshes.
Breeding season takes place from April to May. Females move around surprisingly little for this time instead waiting for males to approach them. Many males will approach a single female using a scent trail which they lay down to find her.
On occasion up to 12 males may vie for a single female. These males wrap around the female in what is known as a ‘breeding ball.’ They will then all attempt to mate with the female in a process which may take four weeks before one experiences success.
This species is capable of giving birth through parthenogenesis. This involves the female fertilizing her own eggs thus meaning she does not need to mate with a male.
Six to seven months after mating the young are born live unlike most snakes which lay eggs. An average clutch contains 20 to 40 anacondas but some have included 100. These young develop in a membrane which they break out of following birth.
They begin life at 70-80cm (27.5-31.5in) long. Following birth they take off and are responsible for looking after themselves. They generally begin by hiding as they are susceptible to predation.
Until sexual maturity at a few years of age these snakes grow rapidly. Growth continues after maturity but at a slower pace.
Green anacondas are nocturnal. Most of their day is spent in the water. A lot of their time is spent floating with the snout sitting above the water.
In areas where the savanna seasonally floods these snakes will find water or bury themselves in the mud while it is dry. The ones which are buried in the mud enter a period of dormancy.
These animals are also referred to as water boas
Their scientific name “Eunectes” comes from a Greek word for good swimmer.
An anaconda is cable of opening the mouth to be almost three times the size of its head.
Anaconda groups are referred to as a bed or knot.
By Dave Lonsdale (Anaconda) [CC BY 2.0 (http://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons
National Geographic. 2020. Green Anaconda. [online] Available at: <https://www.nationalgeographic.com/animals/reptiles/g/green-anaconda/> [Accessed 26 April 2020].
Copyright The Animal Facts 2020
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