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Boa constrictor, Central and South America, up to 4 m (13 ft) long The boa constrictor and the anaconda are both types of boa. Boas are large, constricting snakes from Central and South America that give birth to live young. They seize their prey by the neck and coil around it to suffocate the animal to death. Boa constrictors grow up to 4 metres (13 feet) long. At nearly nine metres (30 feet) long, the anaconda is one of the world's longest and heaviest snakes.


A boa constricting its victim, a rodentThe boa constrictor has an excellent sense of smell and sharp eyesight. Catching an animal's scent in the air, the snake moves silently and with lightning speed. It will first strike at the prey with its teeth. Boas do not have long fangs. Instead, their short, sharp, backward-pointing teeth help them to grasp their prey. It is almost impossible for the victim to escape.
The boa swallows its dead prey whole, head first.The boa then proceeds to coil around its victim and suffocate it to death, a method called constriction. It then swallows the animal head first. It will not need to eat again for several days after feeding. Boas often lie in wait for its victims to come close, before launching an ambush attack. But they will also go in hunt of their prey, usually at night.
Emerald tree boa, South America, up to 1.8 m (6 ft) long.

Early European explorers and native dwellers of the Amazon rainforest claim to have seen giant anacondas measuring up to 18 m (about 60 ft) long, but none of these sightings has ever been verified.

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