An organism that lives at the expense of another species is called a parasite.
From the Latin parasitus (although with more remote origins in a Greek word meaning "commensal" ), a parasite is an organism that lives at the expense of another species . The parasite, which can be animal or plant, feeds on the other organism, weakening it although, generally, without killing it.
The biological interaction involving parasites is known as parasitism . The species that hosts the parasite is known as the host or host and suffers a deterioration in its reproductive capacity due to the action of the other organism that, in turn, manages to improve its own conditions and its ability to survive.
How a parasite works
It can be said, therefore, that parasites benefit from the association they establish with the other organism, while the latter is harmed by the type of interaction .
In some cases, the parasites themselves can become hosts for a third species, which is known as a hyperparasite . In this way, a chain is produced where the hyperparasite lives at the expense of the parasite, and the parasite does the same with its host .
With the passage of time and successive generations, host organisms manage to develop certain defense mechanisms that keep parasites away or minimize their field of action. Parasites, however, can achieve physiological and morphological transformations through natural selection .
It is worth mentioning that symbiotic relationships between a parasite and its host can be beneficial for the life and evolution of the latter, although this is the minority of cases.
Among the parasites is the tick.
Some examples
The action of some of the parasites that most commonly attack our species is detailed below:
* hookworms : they are worms that begin their life cycle outside our body and reach it through fruit, vegetables or contaminated water . Once in the intestine, they stick to its wall and feed on the blood to grow, which can cause a type of anemia known as hookworm . Among the symptoms caused by the presence of these parasites are diarrhea, nausea, loss of strength and pain in the abdomen;
* flatworm trematodes : they find their habitat in the bloodstream of their hosts and are the cause of schistosomiasis (a disease that causes strong fevers and hives, among other symptoms, and can cause death). Before entering another organism, they live in water. Their presence is manifested through damage and inflammation in some organs, mainly in the liver, and they can stay in the same body for several decades, sometimes without showing symptoms for a long time. When they do, these are usually cough, various pains, lethargy and fever;
* wuchereria bancrofti : they are carried by mosquitoes and released into the host's blood . Its larvae go to the lymph nodes, especially in the genitals and lower extremities, and reach adulthood within twelve months. They usually cause a disease from the group known as filariasis , especially elephantiasis (it causes excessive growth of certain parts of the body). Among the symptoms that are noticed in its presence are chills, pain in the lymph nodes, fever and skin infections;
* entamoeba histolytica : is a single-celled organism that attacks people and other primates. It is found in fruits, moist soil and water. Fecal contamination contributes to its spread. It is worth mentioning that the death rate attributed to it exceeds that of the rest of the protozoa. Diarrhea, weakness, weight loss and liver abscess are some of the symptoms of its passage through our body.
Parasite in colloquial language
Finally, a person who lives, or tries to live, at the expense of another subject, taking advantage of their material resources, is classified as a parasite.
For example: “Maximilian is a parasite; Since he has never earned his own money, he would be sleeping on the street if it weren't for his parents.”