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Learning About Leeches


These plump little creatures get a bad rap. Like all of the animal neighbours in the Biosphere, leeches have some pretty interesting features and once we get to know them – from a distance – we might appreciate them a little more.

There are about 700 species of leeches in the world, and 35 species that can be found in Ontario. Not all leeches will stick to you! Some don’t even eat blood but rather feed on snails, mussels, aquatic insects, and fish.

For invertebrates (animals without a backbone) leeches are surprisingly good parents!

They protect their eggs from predators using their own body. They also fan their eggs like octopi do, to prevent fungi and bacteria from growing on them. Even after the baby leeches are born the parent will carry them around until they are old enough to survive on their own!

To bust a common myth, leeches do not transmit any human diseases! It is understandable why people might think that they do. For example, mosquitoes can transmit Malaria and West Nile and ticks can transmit Lyme disease as well as rocky mountain spotted fever. Luckily for us, if you find a leech on your foot you won’t have to worry about disease.

But what if a leech does bite me?!

Leeches have an enzyme in their saliva so when it attaches to you it numbs the spot so you don’t feel it. Leeches have small teeth to make a little cut, and when they start to suck blood, they leave a “Y” shaped mark. The enzyme in their saliva also stops blood from clotting to make the process easier and faster for the leech, this is very similar to ticks.

When a leech is attached to you, you probably want to get it off. Here are some tips to do so safely:


1. Pull them off: This could rip off their teeth which will stay in the wound. This may cause an infection.

2. Use salt or heat: This will cause the leech to vomit into the wound which can also cause an infection.


1. Use your fingernail or a credit card to pry the sucker off your skin. You are basically just putting space between the sucker and your skin and the leech will come off.

2. Leeches will fall off when they are done feeding. If you don’t want to remove them, they will eventually fall off.

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