Appearance• There are about 700 species of leeches.• Leeches look like worms with suckers on each end. They are usually brown or black in colour.• They can be 1 cm to over 25 cm long.• Leeches have eyespots on their head that can detect their prey. Their mouth is under the head and is surrounded by a sucker. The sucker helps draw blood and other bodily fluids into the mouth.• The tail sucker is used for swimming, getting around, or staying attached to prey.• Leeches are segmented worms with 34 segments.• Like earthworms, leeches have a clitellum, a special collarlike band behind the head. This is filled with special tissues that make a protective case for the eggs.
Habitat• Leeches are found in a wide variety of habitats.• Those living in the ocean and the wide areas where rivers join the sea, are found on rocks, plants, or attached to fish or other sea animals.• Species living on land are found in moist habitats, like rainforests or wet coastal forests. They are usually found holding on to plants or under rocks.• Some species are amphibious as they can live in both land and water habitats.
Food• Some leeches feed only on the blood of their prey. Blood- feeding leeches attack fishes, turtles, crocodiles, water birds, and mammals, including humans.• These leeches have a chemical in their spit that stops the blood of mammals from clotting, either at the bite or inside the leeches own bodies. Leeches also have an anesthetic in their spit, which can stop their prey from feeling them feeding.• Leeches can eat many times their body weight in one meal. It takes a long time for a leech to digest its meal so they do not feed often, sometimes only once a year. When they are full of blood they drop off their prey and find a dark place to rest and digest.• Other leeches are predators that eat a wide variety of invertebrates. Prey includes insects, earthworms and other leeches. Some leeches feed on only one kind of animal. Others will feed on anything.
Life Cycle• Egg -The egg is fertilized and placed in a cocoon. The clitellum makes a tough cocoon which contains nutrients, and the eggs are put in it.• Cocoon - The cocoon is either buried or attached to a rock, log or leaf or can also be attached to the bodies of other animals. Some leeches carry their eggs in a clear sac under their body.• Young- Newborn leeches look just like the adults, only smaller. Once a newborn has its first meal it is completely independent.• Adults- Adult leeches reproduce once or twice and then die.
Predators• Fish, birds, turtles and other invertebrates are the main predators of leeches. Leeches are not endangered.
Special Features• Leeches were used in the 17th and 18th century to treat all kinds of sickness, from headaches to being fat.• Aquatic leeches are used to measure environmental health because they are sensitive to heavy metal pollution and low oxygen in freshwater habitats.• Doctors use farm-raised leeches for several kinds of medical treatments. They are used to remove pools of thickened blood under the skin grafts of burn patients. A hungry leech can restore the circulation in clogged veins by sucking out blood clots. They are good for improving the circulation in reattached body parts, such as fingers and ears, by helping to restore blood flow through reconnected veins.• Leeches can be dangerous if they fasten themselves to your eyeball. The only safe thing to do is wait till the leech finishes feeding and drops off. Don’t pull the leech off and don’t apply salt or you may damage your eye.
Thank you for listening. I hope you enjoyed my presentation.