European medicinal leech


Master of fasting

The European medicinal leech is a ringed worm just like the earthworm but unlike the earthworm it lives in water, has sharp jaws and sucks blood.

Feeding and catching

The leech can eat 5-10 times its own weight. The intestine has 22 side pockets that can be filled with blood and store it for over a year. The leech can therefore survive for one to two years before it has to find a new host animal to suck blood from! It can live for 15 years.

This leech is the only leech in Sweden that can suck blood from people. However, the most common host animals are moose, roe deer and cows that go into the water to graze and drink. It is important for the leech to suck quickly and let go before the host animal goes too far into the land again with the risk of falling into dry grass. If the skin get dry the lech dies. If it let go just near the beach, it can wriggle back to the water in damp grass.

Appearance and characteristics

The medicinal leech has two suction cups. One big posterior that is used mainly for leverage and a small one around the mouth for holding and eating!

With the help of its suction cups it can "walk" just like a geometer larva. It can also swim with undulating body movements. When it finds a host animal, it fasten itself in with its front suction cup. In that suction cup is the mouth, which consists of three jaws shaped as an up and down Y (as a Peace mark). On the jaws sit several hundred tiny sharp teeth. The jaws are moved back and forth and with the help of the sharp little teeth they cut through the skin like a scalpel.

The leech directly spits saliva into the wound and in the saliva there is an anesthetic. This means that the host animal does not notice what the leech is doing. The saliva also contains hirudin, a substance that prevents the blood from clotting and prevents the leech from drinking.


The European medicinal leeches are hermaphrodites (both male and female) and their egg cocoons are laid in the shoreline in midsummer.

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