What Kind of Worms Are Leeches?

Leeches are often called "bloodsuckers," and can be found in swamps, marshes, rivers, streams and bogs throughout the country. Leeches are one of the three types of worms, and they belong to the Hirudinidea class. They live by sucking on the blood of living animals, such as humans, deer, fish, cattle and other larger mammals.

  1. Types of Worms

    • Worms are classified as annelids because of their external body structure, which features long cylindrical bodies with no appendages, no antennae and no obvious head segment. Within the class, there are three groups: oligochaeta, hirudinidea and polychaete. Oligochaeta consists primarily of earthworms and other worms that inhabit the soil. Both polychaete and hirudinidea can be found in marine environments, but polychaete inhabit deeper waters in the oceans and seas. Hirudinidea, which are leeches, can be found in more shallow waters.

    Appearance

    • Adult leeches range in size from about half of an inch to 6 inches, depending on the type of leech. Leeches have two large suckers on the tail and the head. Typically, the smaller one on the head has a set of jaws and sharp teeth that allow a leech to grab on to flesh and stay attached to the host. Leeches have a bunch of eyes, which can sometimes be found on both the tail and head. The eyes allow leeches to detect changes in light and darkness, which helps them sense when a potential host is close by.

    Bodies and Movement

    • Leeches are contortionists, which means that they can stretch their bodies into slender shapes and also widen themselves when they are full of blood. Leeches can swim in the water by wagging their tail end, similar to the way in which a snake swims. They can also roll on the ground, using a method where they wrap themselves into balls to create a rolling motion.

    Types of Leeches

    • There are four main types of leeches: ribbon, horse, tiger and medicine. Ribbon leech live in the water and attach themselves to fish and other animals that might bend down to drink out of the water.

      Tiger leeches hang on leaves and branches, and they wait for animals to pass by so that they can jump onto them.

      The horse leech is the most common type of leech that sucks on human blood. These leeches hang out in shallow waters and await humans and other mammals to pass by.

      Medicine leeches are used in a variety of medical procedures, and they can help reduce the spread of cancer, take blood away from wounds and eat bacteria in the digestive system.