Leeches

Leeches Fact

Leeches are annelids comprising the subclass Hirudinea. There are freshwater, terrestrial, and marine leeches. Like the Oligochaeta, they share the presence of a clitellum. Like earthworms, leeches are hermaphrodites. Some, but not all leeches are hematophagous.

There are 650 known species of leeches. The largest leech discovered measured 18 inches. About one fifth of leech species live in the sea, where they feed on fish. The leech has 32 brains - 31 more than a human. The Hirudo leech lays its babies within a cocoon; whereas the Amazon leech carries its babies on its stomach - sometimes as many as 300. Not all leeches are bloodsuckers. Many are predators which eat earthworms, etc. The Amazon leech uses a different method of sucking blood. It inserts a long proboscis into the victim, as opposed to biting.

The bite of a leech is painless, due to its own anesthetic. The Hirudo leech injects an anti-coagulant serum into the victim to prevent the blood clotting. The leech will gorge itself until it has had its fill and then just fall off. The leech will gorge itself up to five times its body weight.