But, it started to stretch and it was at least 3-4 inches long. But really, they are only staying alive by sucking blood from other animals but not humans. The leech gives off a chemical called hirudin which is useful in surgeries. The leeches' bite is not poisonous, but its bite can open the way to infection just as a mosquito bite can. Leeches go after fish, turtles, frogs, frog eggs, snails, worms, and other leeches.
Leeches are flat worms with segments.
They are often found in water that is not very deep, not too rapidly moving, and warm. The bottom of their water is always muddy. Leeches don't have much color. Inside the Leech Instead of a heart, a leech has four long veins and simple blood vessels. The leech gets oxygen through its skin.