There are two species of anaconda, both of which are large constricting snakes found in South America. The green anaconda is much larger and more famous than its yellow relative

Green Anaconda:Eunectes murinus

The green anaconda is known as the biggest snake in the world. The reticulated python is often longer, but the green anaconda is much heavier. They may reach a length of about 10 metres, and there are unsubstantiated reports of specimens twice as long. The green anaconda is thickly set, and can weigh as much as several fully grown men. Anacondas are constrictors, and are not poisonous, but due to their large size they are dangerous to man. Green anacondas have a dark olive colouring, with black bands across the back. The eyes point upward to allow the anaconda to look up out of a body of water.

Another name for the green anaconda is the water boa. This is because it spends most of its time in the water. It favours stagnant or swampy areas, and can be found in much of tropical South America. Green anacondas usually wait by the water's edge for a prey animal to approach. After biting a target and holding on the green anaconda throws several loops of its heavily muscled body around its victim. As the victim exhales the anaconda contracts, preventing inhalation. After the prey has died of suffocation, the anaconda will begin to swallow it, almost always from the head down. The jaw of the green anoconda can dislocate to allow it to swallow large animals, such as wild pigs or humans whole. These snakes can live for several weeks of a large meal. The usual prey of such a snake includes all the large mammals that may be found in the tropical forests of South America.

Anacondas mate in the water. There may be competition between males for females, who are usually slightly larger. About six months after mating has taken place, the female gives birth to around 40 infants. These are already two feet long, and are capable of swimming and hunting for themselves almost immediately.

Due to nocturnal habits green anacondas are rarely seen, but should be feared, due to their vast power, and violent tempraments.

Kingdom: Anamalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Family: Boidae

Yellow Anaconda:Eunectes notaeus

Much less impressive than its cousin, the yellow anaconda reaches only about 2 metres in length. They are predominanlty yellow in colour, and their range is slightly to the south of that of the green anaconda. They are similar in most behavioural and physiological respects.