Sunday, January 8, 2012

Venom


Among flesh eating animals, the use of venom is a method of subduing prey that cuts across taxonomic boundaries. Generally, venomous animals are small, slow-moving or fragile. The delicate tentacles of a Portuguese man of war, for instance, deliver paralyzing stings. Were it not for this, it would be thrashed to pieces by the struggles of its prey. With a poisonous bite, short sighted spiders prevent insects escaping. Snakes such as vipers or cobras use venom to still fast moving small mammals.

While each kind of venom is chemically slightly different, almost all have a dual function. The first is to act on the nervous system of the prey, paralyzing it and preventing its escape. The second function is digestive, for venoms contain proteolytic enzymes that break down animal tissue. A spider has no need to chew its food; after a while it merely sucks up a largely predigested meal. The mouse eaten by a venomous snake is at least partly digested by the injected poison.