Leeches

Leeches

Leeches in Australia ~ Leeches are worms. There are aound 700 species, found all over the world, mostly in freshwater and oceans. Australia’s leeches are unique in that they live on dry land. On every other continent they only live in water.

Did you know?

Leeches are parasitic or predatory worms. Their scientific name is Annelida hirudinae. They are related to earthworms. Their skin is extremely tough, unlike earthworms that have very fragile skin. They feed by attaching to their prey with a sucker, glueing themselves in place with mucus, then secreting a substance called peptide hirudin. Hirudin is an anticoagulant that stops the blood from clotting so it will flow easily into the leech, and an anaesthetic so it numbs the area so you don’t feel it is there so you don’t pull it off. Some leeches only eat twice a year, so they need to take in an enormous feed. Their coelom, or gut, is made up of many small channels designed to stretch and fill with blood. Their very solid bodies and their super tough skin make it possible for them to stretch to many times their fasting body size to take in this feed.

Human benefits

Although the idea of leeches can be horrible, they are not dangerous for humans. The amount of blood they take is tiny and, although they can cause a localised infection at the bite site, this is rare and usually mild and easily treated. The bite site can be very itchy for a few days, much like a mosquito bite.

Leeches play a very important role in medicine. They have been used in medicine for hundreds of years. Until the 19th century they were used to draw blood from sick people as it was thought that illness was caused by having “bad” blood, or too much blood. Today, leeches are used in medical treatment in different ways for different conditions e.g. they may be applied to a wound site after micro surgery to reduce blood collecting in the area, and to prevent clotting while the tiny blood vessels heal.