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Common Name: North American Leech

Scientific Name: Macrobdella decora

Kingdom: Animalia

Phylum: Annelida

Class: Hirudinida

Order: Arhynchobdellida

Family: Hirudinidae

Genus: Macrobdella

Species: M. decora


The Macrobdella Décora or the North American Leech is quite popular. You may have seen them in the movie "Stand by Me". The upper surface of their body is olive colored with a row of orange spots down the middle. The bottom is orange. Most leeches are really colorful. They can grow to be 3.9 inches (100 millimeters) and 0.39 inches wide (10 millimeters). They are found in freshwater lakes, ponds, streams, and marshes. They are excellent swimmers; they can detect prey from about 10 yards away. They follow the waves in the water. They may vary in sets of eyes. A leech has three muscular jaws. One is the colors and the other two are ventrolateral. Each jaw has a row of sharp teeth.


Leeches have an oral sucker instead of lips this sucker is very strong. When they move their jaws back and forth across your skin it cuts your skin then they use their sucker to make a seal around the incision so it can suck the blood and get it straight to the stomach. Leeches feed for about half an hour before they stop. But since they are so small they only need to feed about once a month. Then they go hide wherever and stay there while their food digests slowly. By the way, the wound you get from the leech is not very big and not very deep. Leeches feed on mostly amphibians, and fish blood. It occasionally feeds on mammals.


Leeches have something called Anticoagulants (a substance that prevents blood from clotting) in their saliva. They need this because without it a blood clot could occur in their stomachs and it could kill them. How do leeches mate? Sperm is deposited directly into the female reproductive organs. Up to ten or more eggs are laid in the cocoon. The cocoons are deposited on land near the edge of the water.


Did you know that the North American leech was used by the Osage Native Americans? Well, now you do. Two things that I found most interesting about these leeches are the way that the three jaws are shaped causes it to leave a Mercedes Benz like mark. Also when a leech gets on your skin it doesn’t start eating right away. First, it tries to find a soft place on your skin to feed on. It can sense where on your skin the blood might “taste” right. So basically if you were to put a leech on your skin it would take a while before the leech would actually start eating. 


Author: Nadine R

Published: 04/2008


Sources: Photo Credit: Astrid & Hanns-Frieder Michler/Photo Researchers Inc.

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