Parasitism is a type of symbiotic relationship where one organism benefits at the expense of another organism. The parasite is the organism that benefits, while the host is the organism that is harmed, however the severity in which a parasite harms its host varies greatly. There are different types and mechanisms of parasitism which we will explore in this article.
While parasitism is often viewed as a negative phenomenon, it plays an important role in many ecosystems. Parasites can help regulate the populations of their host species, and can also serve as a food source for other organisms. In addition, some parasites have evolved to live in harmony with their host, and have developed complex strategies for avoiding or mitigating the host’s immune system.
4 main types of parasitism
There are four main types of parasitism that occur in the natural world. Continue reading to learn more about these mechanisms as well as an example of a parasitic relationship for each type.
Endoparasitism is a type of parasitism where the parasite lives inside the body of the host. This can be in various organs or tissues such as the intestine, liver, or blood. Endoparasites can be found in a wide range of organisms, including humans, animals, and plants.
Endoparasites can cause a range of diseases and health problems in their hosts. Some common endoparasites in humans can cause diseases such as malaria, trichomoniasis, and toxoplasmosis. These parasites can have a wide range of impacts on the host, from mild discomfort or weight loss to serious illness and even death.
Endoparasitism can also have significant impacts on animal health and welfare. For example, some endoparasites in animals can cause weight loss, reduced growth rates, and reduced milk production in livestock.
In wild animals, endoparasites can affect behavior and reproductive success, and can also have population-level impacts.
Example: Tapeworms and Humans
Tapeworms are a type of flatworm that live in the intestines of humans and other animals. They are long and flat, with a segmented body that can grow up to several feet in length.
Tapeworms attach themselves to the intestinal wall of their host and feed on the host’s nutrients. In humans, tapeworms can cause abdominal pain, nausea, and sudden weight loss.
Scarily enough, tapeworms have been used in the modeling industry by models wanting to lose weight quickly and with minimal effort.
Ectoparasitism is a type of parasitism where the parasite lives on the surface of the host’s body and are often visible to the human eye. Ectoparasites can be found in a wide range of organisms, including mammals, birds, reptiles, and insects. Common examples of ectoparasites include ticks, fleas, lice, and mites.
Ectoparasites can cause a range of health problems in their hosts, including skin irritation, hair loss, anemia, and the transmission of diseases. For example, ticks can transmit diseases such as Lyme disease and Rocky Mountain spotted fever to humans and animals.
Fleas can even transmit endoparasites like tapeworms and other diseases to pets and humans, while lice can cause skin irritation and transmit diseases such as typhus.
Example: Ticks and vertebrates
Ticks are bloodsucking parasites that attach themselves to the skin of animals and feed on their blood. They can transmit various diseases, such as Lyme disease, Rocky Mountain spotted fever, and tick-borne encephalitis to their mammalian hosts.
While ticks are most known for feeding on mammals, they are also known to attach themselves to other land-dwelling animals like reptiles. They even latch themselves onto the shells of tortoises where they use their sharp, razor-like mouth parts to suck their blood through their shell.
3. Brood parasitism
Brood parasitism, sometimes also known as social parasitism, is a type of relationship that occurs outside of the host. Instead, it involves one species exploiting the social behavior of another species.
In social parasitism, the parasite does not necessarily live inside or on the host’s body, but instead takes advantage of the host’s social structures and behaviors for their own gain.
As the name would suggest, brood parasitism is most common in the avian world but it also occurs in fish and insect species. Most of the time, it involves the parasite exploiting another species by placing their eggs or young in the care of the host species without the host species realizing.
Then, the host species raises up the parasite’s young without the parasite needing to expend the effort or resources to raise a healthy offspring.
Example: Cuckoo birds and other birds
Cuckoo birds are arguably one of the best well known brood parasites. They will secretly lay their eggs in the nest of another bird.
If there are eggs there already, the mother cuckoo will push the other bird’s eggs out of the nest. Then, the cuckoo’s egg hatches first, and the chick ejects the host eggs or nestlings from the nest, ensuring that it receives all the parental care and resources available.
This is a another type of parasitism where the interaction does not happen within or on another species. Instead, it occurs when one species steals food or resources from another species.
This behavior is commonly observed in birds, where some species steal food from other birds without needing to do the work of hunting or collecting the food. This can happen between different species or even between members of the same species.
It often requires a lot of effort and energy expended in order to hunt or capture prey, so kleptoparasitism can have significant impacts on the host species, including reduced reproductive success and increased mortality rates. In addition, kleptoparasitism can also have ecological impacts, as the presence of kleptoparasites can disrupt food webs and alter the distribution of resources in ecosystems.
Example: Fork tailed drongo and meerkat
The fork tailed drongo is a type of bird that uses its wit and false alarm calls to rob meerkats of their food. Drongos often follow meerkats while they hunt and have been known to make alarm calls when predators of meerkats, like hawks, are nearby.
This alarm call causes the meerkats to quickly hide and find cover. While this might sound like an example of commensalism, these drongos will oftentimes let out a false alarm call and quickly gather up the food that the meerkats have collected for themselves.