Leeches (Class Hirudinea)

Key features:
- flat underside
- circular, sucking mouth
- size range:  1/2" - 4" when extended (see text)

Leeches are usually small, dark in color, and flat. They tend to cling to smooth stones and boulders with their circular "sucker." Leeches generally have the appearance of being segmented, with the lines running perpendicular to the length of their body. They may be long and tapered, or short and tear-drop shaped. They move by extending and contracting their tough muscular bodies, so they may appear quite long. Do not confuse these with the flat soft-bodied planaria.