7 Things Leeches Like to Eat (Diet & Facts)

Unlike what most people think, leeches are not a species of their own. Instead, they are a type of parasitic worm that attaches themselves to other animals and even humans. Their whole bodies are made of muscles, and they are fairly mobile with a strong grip.

In this article, we will talk about what do leeches eat and review other interesting biological traits.

Leeches Habits and biology

Leeches Habits and biology

Individuals belonging to this species are very similar to each other. In that sense, they are different from most annelid animals. The species have coelom with four longitudinal channels. The inside of their bodies has strong dermis tissue, which isolates specific organs and prevents them from damaging each other.

The animal’s body has an epidermis, cuticle, and a layer of connective tissue. Leeches are very flexible due to their potent diagonal muscles that envelop circular and longitudinal muscles and reinforce them. Almost all species have a sucker on the front and end of their bodies, but some primitive leeches only have one in the back.

The species reproduces like all other hermaphrodites. They have both sets of organs, but male sexual tissue will be formed first. When two animals copulate, they do so by connecting one animal’s anterior end with another individual’s posterior end. The penis will ejaculate the spermatophore into the female organ, which will then be stored in the vagina.

Here are some interesting habits that leeches exhibit:

  • Although the animal has both sets of sex organs, they are not active at the same time. Instead, they only activate at certain moments in their lives. So, when mating, they need to find a partner who has the other set of organs active at that moment.
  • The animal will place fertilized eggs into a cocoon within its reproductive system. This can occur after a few days or a few months; it depends on leech species.
  • The animal loves shallow, warm ground with lots of natural protection and obstacles. Leeches avoid light whenever they can and tend to hide under stones and plants.
  • The species is very resilient and can survive for more than a year without any food. However, when they have the opportunity to eat, they can consume an amount of blood several times their weight. As such, fed leeches will be very bloated.

What do leeches eat in the wild?

What do leeches eat in the wild

The majority of leeches suck blood, and biologists categorize them as parasitic species. But there are also those that eat prey whole. They are very selective when choosing targets. Still, if food is scarce, they will try to get blood from animals they wouldn’t otherwise attach to.

Depending on leech subspecies, they can feed on various mammals, fish, humans, birds, etc. In some cases, they will take food from other leeches that have died during an attack. After eating several times its weight, the animal will detach from its target and go to some dark, covered spot where it will process food. The whole digestion process is very slow, and it can last for months. As such, the species doesn’t have to eat all the time.

If we were to generalize, here are all the things they eat:

  • Fishes (blood)
  • Amphibians (blood)
  • Mammals (blood)
  • Birds (blood)
  • Worms (meat)
  • Larvae (meat)
  • Snails (meat)

The animal can feed in various ways depending on its species. For example, one group of leeches have jaws with very sharp teeth allowing them to bite their prey. In addition, the animal synthesizes unique secretion, which it injects into the host’s body, thus preventing clotting. That way, they can suck blood for a long period.

Unlike the first category, the second type of leeches doesn’t have jaws. Instead, they utilize a specific type of needle to sting their host. Once they do so, they will inject them with enzyme hematin that allows the dissolution of blood clots. These subspecies usually attack smaller animals such as snails and worms.

Lastly, we have leeches without jaws or teeth that feed by swallowing other animals.

Leeches can easily and quickly analyze their surroundings. By fully extending their bodies, they can better feel the motion around them. Once they feel disturbance from a potential host, they will start crawling and sucking the ground. They will continue doing so until their sucker feels meat. Such behavior is much more common for aquatic subspecies, while land leeches usually attach to their hosts by accident.

Facts about leeches

Facts about leeches

When talking about parasitic animals, the first thing most people think of is leeches. This species has lots of interesting characteristics. Here are some very interesting facts about the animal:

  1. For the longest time, leeches were used as medical animals. Doctors thought that this species was great for treating serious diseases. One of the old beliefs was that excess blood was the main cause of numerous human ailments. Although leeches are no longer used in the same capacity, modern scientists are still interested in their potential. A few studies explore how the animal could help people with detached limbs. According to theories, leeches could be able to help reduce swelling and prevent loss of blood. Furthermore, the US FDA has approved the animal for such use from 2004 onward.
  2. Unlike many worms, leeches cannot burrow. When they crawl, they utilize suckers on their posterior and anterior. By doing so, they can anchor their bodies and substrate.
  3. On the other hand, this species is great at swimming and often finds its prey in water. They can also dive even though they don’t have gills. When under the water, they can absorb oxygen via body walls.
  4. Leeches can stay on hosts for such a long time because their saliva works as a painkiller. Once they start sucking, they will also numb the area, so it is less likely that the animal will notice them.
  5. For the most part, leeches are harmless to humans. When they bite a person, the substance hirudin will prevent clotting, so you might leak blood for several hours. However, the puncture hole is usually so small that you won’t lose too much. But the problem comes with bacteria. Microorganisms will infect some leeches, so there is a chance they will transfer them to humans via a bite. Some people might also experience an allergic reaction.
  6. In certain regions of the world, leeches can pose a nuisance. So, people developed various protection methods. Although there are no commercial products against these animals, there are a few things that you can use against them. For example, people apply substances such as strong insect repellants, eucalyptus oil, lemon juice, etc.
  7. Although this animal attacks large and small animals, it is also hunted by numerous species. Birds, snakes, fish, amphibians, and sometimes even insects tend to feed on leeches.
  8. Silted substrates represent a major issue for the animal as it cannot crawl on such a surface.
  9. While these animals can’t dig like worms, they have limited burrowing ability. Leeches tend to use it when there is a major drought. They will create a hole in the ground and line it with mucous, waiting for better weather.
  10. Leeches can eat various prey and survive in different weather conditions. As such, they live on all continents except Antarctica. You can find them in various bodies of water but also on the ground. There are more than 500 subspecies of this animal.
  11. One species of leeches called Rhyncobdellids can change its color. However, this function doesn’t have anything to do with camouflage. Experts are still baffled by this and to this day cannot provide a rational solution.
  12. The animal has a very complex anatomy. They have six hearts, ten eyes, ten blood pouches, 32 brains, and 200 different enzymes, allowing them to store fresh blood for up to three months.
  13. Although many people refer to leeches as medieval medicine, they weren’t used that much during this period. The animal was first utilized for medical purposes 5,000 years ago in India. Their medical use peaked in 19th century France.
  14. The largest subspecies of this animal is the giant Amazon leech. They can grow to 18 inches long and, in extreme cases, they can live for 20 years.
  15. Leeches are very engaged parents. After laying eggs, the mother will cover them with their body. By doing so, they prevent bacteria and other microorganisms from affecting the offspring. Once the young are born, they will attach to the parent to carry them to their first host.


Most people associate leeches with medieval medicine. However, we were using these animals for healing long before that. Even today, there are some attempts to utilize leeches for the treatment of severely wounded people.

As you probably know, these animals feed by sucking blood off of animals and humans. But certain species eat meat. They have strong suckers that can swallow small insects whole.

Leeches are hermaphrodites. Each one of them has male and female sex organs. They will be active at different times in their lives so the same individual can perform the duty of a female and a male in their lifetime.

2 thoughts on “7 Things Leeches Like to Eat (Diet & Facts)”

Leave a Comment