Leeches are classified into two groups: the true leeches and the false leeches. The true leeches have a sucking mouth, which is called the proboscis, and they are found in freshwater or saltwater. They live on blood, but not all of them do so. Some of these leeches feed only once a year while others may feed several times a day.
The second group includes the false leeches, which have no sucking mouth and live in freshwater. These leeches can be divided into three subgroups: the Haemopidae (bloodsucking worms), the Rhyncobdellida (gill-footed leeches) and the Hirudinea (true leeches).
Different Types Of Leeches (Based on Habitat)
Leeches can be broadly classified into three types based on their habitat: terrestrial, freshwater, and marine. Marine leeches live in saltwater. Freshwater leeches live in freshwater. Terrestrial leeches live on land. Each type of leech has its own unique characteristics. Some leeches exhibit only one kind of behavior while others exhibit more than one kind of behavior.
For example, some leeches will attach themselves to a host and feed off of the blood of the host. Others will bite into the flesh of the host. Still others will inject saliva into the host’s bloodstream.
Below we have discussed about each of these different types in detail:
Marine Leeches
There are three main groups of marine leeches: true leeches, false leeches, and ribbonworms. True leeches are flatworms with eight segments. Their body is divided into a head, trunk, and tail. Most true leeches live in saltwater. Some true leeches are filter feeders. Others use their long proboscises to sieve food particles from seawater. True leeches are not parasitic.
False leeches are similar to true leeches but lack the proboscis. Instead, they have a pair of hooks on either end of their bodies. Ribbonworms are very slender, soft-bodied animals. They do not have any segmentation. Instead, they resemble a piece of string. They are often mistaken for sea cucumbers. Ribbonworms are found in shallow seas throughout the world.
Freshwater Leeches
Leeches can be found living in fresh water. There are several different types of freshwater leeches. One type lives in stagnant waters. This group includes the American dog leech, the European dog leech, and the African bulldog leech. Another group of leeches lives in fast moving waters.
These include the American eelworm, the European eelworm, and the Australian eelworm. Still another group of leeches lives along the banks of rivers and streams. These include the American moccasin leech, the European moccasin leech and the Asian moccasin leech.
Terrestrial Leeches
Leeches are sometimes referred to as terrestrial leeches. However, most leeches spend their entire lives in the water. Only a few species of leeches are capable of living on land. Two of these species are the American earthworm leech and the Japanese earthworm leech. Both species are members of the family Glossiphoniidae. Earthworm leeches are very small. They have no segmentation. Instead, their bodies are covered with hundreds of tiny bumps.
They are also blind. They cannot see anything. Like all leeches, earthworm leeches attach themselves to hosts and feed off them. Unlike other leeches, however, earthworm leeches do not need to stay attached to their hosts while feeding. Instead, they can detach themselves from their hosts and walk around freely.
Different Kinds Of False Leeches
Here are the subgroups of false leeches found across the globe:
Blood Sucking Worms:
Bloodsucking worms belong to the order of Annelida and include such creatures as earthworms, slugs, snails, leeches and ticks. Only one species of bloodsucking worm has been identified in North America. This species belongs to the family Glossiphoniidae and lives in the soil. It feeds on insects that it finds in decaying vegetation.
Gill Footed Leeches
Gill-footed leeches are also known as “leech lice” because they resemble small crabs. They are members of the class of mollusks, the Cephalochordata. There are more than 100 species of gill-footed leeches worldwide, including at least 20 species in North America. Most of these leeches feed on fish, amphibians, reptiles, birds, mammals and humans.
Gill-footed leech larvae are parasitic on other invertebrates, especially aquatic insects. Gill-footed leaches have four pairs of legs with suckers on their undersides. Each sucker consists of a pair of hooks and a pad of tissue. When the leech attaches itself to its prey, it inserts its hooks into the skin and then pulls out some of the flesh.
The leech’s saliva contains an enzyme that dissolves the epidermis around the wound. Then, the leech sucks up the blood. After feeding, the leech retracts its hooks and leaves behind a trail of mucous. The mucous helps protect the leech from being eaten by predators.
Hirudinea
True leeches are members of the phylum Arthropoda and are characterized by having a body covered with a series of segmented plates. There are about 1,000 different species of true leeches worldwide, including about 60 species in North America. All true leeches have a single pair of long, slender, muscular jaws.
Their mouths consist of a pair of teeth, each tooth consisting of a crown and root. The roots of the teeth fit into grooves cut into the jaw. A true leech uses its jaws to grasp onto its prey. Once attached, the leech will inject a venom through its salivary glands. This venom causes the victim to lose consciousness and bleed profusely. The leech then begins to suck the blood.
The amount of blood sucked depends upon the size of the leech. Smaller leeches usually take less blood than larger ones. In addition, the rate of blood loss varies depending upon the type of leech. For example, true leeches usually feed for only 10 minutes before releasing their victims. However, large leeches may remain on their prey for hours.
The leeches described above are all parasites. Parasites are organisms that live off another organism without harming them. Parasitic leeches are not harmful to people or animals. Instead, they use the host animal as a place to reproduce. Some parasitic leeches lay eggs inside the host’s tissues. Others attach themselves to the outside of the host’s body. Still others insert their eggs directly into the host’s bloodstream.
There are many types of parasitic leeches found throughout the world. Many of these leeches are harmless to humans. However, there are certain species of parasitic leeches that cause serious health problems. For example, the leech Haementeria officinalis is commonly found in Europe. This parasite is responsible for causing a disease called amebic dysentery. Amebiasis occurs when H. officinalis enters the human intestine and lays eggs.
These eggs hatch in the intestines, where they grow rapidly. As a result, the intestinal walls become inflamed and ulcerated. Leeches can also enter the urinary tract and cause kidney damage. Other parasitic leeches include those belonging to the genera Echinobothrium, Neobenedenia, Paragonimus, Schistosoma, Spirometra, Taenia, Thysanosoma, Tunga, Trypanosoma, Varelaia, and Xenopeltis.
What is the lifecycle of parasitic leeches?
Parasitic leeches begin life as free-living creatures. They are born in freshwater streams, rivers, ponds, lakes, and marshes. At this stage, they are called cercariae (Latin: “little tail”). The cercariae emerge from the water and swim toward the bottom of the stream. Here, they come across a suitable host such as a snail, worm or insect. If the cercariae find a suitable host, they penetrate the surface of the host using their tails. Inside the host, the cercariae develop into juvenile worms. Juvenile worms are called metacercariae (“middle tail”).
Metacercariae are able to move independently and crawl away from the host. The metacercariae eventually settle down to form cysts. Cysts are small sacs filled with eggs. When conditions are favorable, the cyst bursts open and release the eggs. The eggs hatch into larvae called miracidia (“miracle” because they appear out of nowhere).
Miracidia are tiny aquatic creatures that look like tadpoles. Miracidia infect other snails, fish, insects, or crustaceans. After being infected, the host becomes a carrier of the parasite. The larva develops within the host until it reaches maturity. Maturity indicates that the parasite has reached sexual reproductive capacity. It is at this point that the parasite changes from a larval to an adult form. Adult forms are known as adults (or adults) and have two pairs of tentacles on each side of their bodies. Adults also have suckers on their heads.
In some cases, the adult may be attached to the skin of the host. In other cases, the adult may remain free swimming in the water. Once the adult is ready to mate, it attaches itself to a suitable host. The female deposits her eggs near the mouth of the host.
The male then fertilizes the eggs. The fertilized eggs turn into larvae called sporocysts (“spore-like”). Sporocysts are immature stages of the parasite. Sporocysts are usually located in the stomach of the host.
Sporocysts contain thousands of spores. The spore is the reproductive cell of the parasite. The spores are released by the sporocysts and travel through the body of the host. Eventually, the spores reach the digestive system of the host. The spores mature inside the host’s digestive system. The parasites reproduce sexually. A new generation of parasites emerges from the host’s tissues. The cycle begins again.
What Are The Adaptations Of Leeches?
Leeches have several adaptations that help them survive in their environment. Some of these adaptations include:
• They have long slender bodies that allow them to glide over surfaces.
• Their eyes are positioned on top of their heads so that they can see what is going on around them.
• Their mouths are equipped with teeth for chewing food.
• Their blood vessels are very thin and flexible. This allows the leech to squeeze its way through tight spaces.
• Their bodies are covered with mucus that helps keep them slippery.
How Do Parasitic Leeches Affect Humans?
There are many different kinds of parasitic leeches. Some of these types of leeches affect humans more than others. For example, the following are some of the most common types of leeches found in North America:
- American Dog Tick Leech – Found in the eastern United States and Canada. These leeches attach themselves to dogs, cats, horses, cows, sheep, goats, deer, raccoons, opossums, squirrels, birds, frogs, turtles, lizards, snakes, and even people.
- Brown Dog Tick Leech – Usually found in the southeastern part of the U.S., but sometimes found in northern states. These leeches attach to dogs, cats, rabbits, rats, mice, ducks, chickens, geese, swine, cattle, horses, sheep, goats, mules, donkeys, camels, and elephants.
- Greenhouse Leech – Found throughout the world. These leeches attach only to plants such as tomatoes, cucumbers, melons, peppers, eggplants, squash, beans, peas, potatoes, strawberries, grapes, figs, apples, pears, peaches, plums, nectarines, apricots, cherries, almonds, walnuts, bananas, avocados, mangoes, papayas, guavas, kiwis, and oranges.
- Red House Leech – Found throughout Europe, Africa, Asia, Australia, New Zealand, South America, Central America, Mexico, and the Caribbean. These leeches attach mainly to rodents, bats, birds, reptiles, amphibians, and small mammals.
- Slender Leech – Found worldwide. These leeches attach mostly to fish, waterfowl, and other aquatic animals.
- Vampire Leech – Found worldwide except Antarctica. These leeches attach primarily to birds, reptiles, and mammals.
- Water Leech – Found worldwide, especially in tropical areas. These leeches attach almost exclusively to fish.
- Yellow Pond Leech – Found in ponds, lakes, streams, and rivers. These leeches attach predominantly to fish, frogs, and salamanders.
- White Pond Leech – Found worldwide in fresh or saltwater habitats. These leeches attach principally to fish, frogs, turtles, and salamanders, although they also occasionally attach to mammals.
What Are The Symptoms Of A Parasitic Leech Infestation?
The symptoms of a parasitic leech infestation vary depending on which type of leech you have. If your pet has been bitten by an American dog tick leech, it may look like a mosquito bite. It will usually be red, swollen, tender, and itch intensely. You should take your pet to the veterinarian immediately if this happens.
If your pet has been bitten or scratched by a brown dog tick leech, he or she may appear lethargic, have difficulty breathing, and feel weak. Your pet may also experience vomiting, diarrhea, fever, depression, loss of appetite, muscle weakness, and seizures.
If your pet was bitten or scratched by a greenhouse leech, he or she may have a rash that looks like a sunburn. This is because the leech secretes a substance called histamine into the skin when it bites.
If your pet was bitten or scraped by a red house leech, he or
she may have a sore that feels warm and painful. This is caused by the leech injecting its saliva into the wound.
If your pet had a leech attached to him or her at any time, he or she may develop a lump under the skin where the leech was attached. This can occur anywhere from one day to several weeks after being attacked.
If your pet’s leech was bitten by a white pond leech, he or she might have a large area of swelling, pain, and discoloration around the site of attachment.
If your pet’s leech were yellow pond leech, he may have a reddish-brown bump around the site of attachment that lasts for several days.
If your pet got bit by a vampire leech, he or he may have a dark circle around the mouth. This is due to the leech sucking blood from the animal.
If your pet gets bit by a water leech, he or she may have a circular area of redness around the site of attachment lasting for several days.
