Anatomy from the medicinal Leech (hirudo medicinalis)

The medicinal blodigel (lat. hirudo medicinalis) is related as worm to the earthworm. The blodigel became smaller an oval cross section at the two body ends. At the two ends is in each case a suction cup. The suction cup in the back, serves the blodigel only for holding. The suction cup contains the mouth opening in front.

In the mouth the jaw those is appropriate for 3 approx. 80 lime denticles has. The three radially arranged jaw have approx. 80 fine lime teeth. At each suction cup is a nerve ring. The body is flattened and consists of 33 segments. The back is dark green and has at both sides ever 3 brown longitudinal strips. The blodigel does not possess a brain.

For surviving the blodigel needs a damp environment, since it would drain otherwise. In the time of sheding its skin, the blodigel is unpowered because of this work.

In the water the blodigel induces itself like a dolphin, ashore uses the blodigel its suction cups to progressive movement. The blodigel supervises the water movements in the water, to which it recognizes potential victims.