We explain what parasitism is, the types that exist and some examples. Also, what is social parasitism.
What is parasitism?
Parasitism is a close biological relationship between two organisms of different species, one called a host (that receives or welcomes) and another called a parasite (that depends on the host for some benefit). The parasite lives at the expense of its host, that is, it uses the organism that hosts you to cover your basic needs, allowing you to expand your own survivability. In most cases of parasitism, the host is harmed or damaged by the parasite at some point in the cycle.
Parasitism can occur throughout all phases of the life of an organism or only in specific periods. It may also happen that, as the parasite is still an organism, it hosts another specimen. These cases, in which the parasite hosts another parasite, are called hyperparasitism.
Types of parasitism
There are several ways to classify parasites, based on different criteria.
- Depending on the location of the parasite in the host's body:
- Ectoparasites. They are parasites that are outside the host's body and take advantage of what they find in the outermost layer of the dermis and even consume a little of their blood. For example, fleas and ticks.
- Endoparasites. They are the parasites that are inside the host. Depending on the species of the parasite, some can cause slight damage and others, very serious. For example, the worms that live in the intestines.
- According to the level of dependence that the parasite has on the host:
- Facultative parasite. They are those species of parasites that do not need the host to complete their life cycle since they are capable of another form of life in addition to the parasitic one.
- Obligate parasite. They are those species of parasites that are totally dependent on their host at all stages of their life cycle and, therefore, cannot live without it.
- Accidental parasite.They are free-living organisms that, by mistake, reach the interior of an organism that is not their usual host, but despite this they manage to survive.
- According to the time the parasite stays in its host:
- Temporary parasites. They are those that only require the host temporarily and to feed.
- Periodic parasites. They are those who need to pass one of the stages of their life cycle (egg, larva, juvenile or adult) within the host, but then live freely.
- Permanent parasites. They are those that require the host throughout their life cycle in order to survive.
Examples of parasitism
On our planet there are many examples of parasitism, among them, some of the most common are the following:
- Mushrooms. There are species of fungi that are parasites. They usually stay on the feet, nails or skin of animals and feed on keratin, a protein abundant in the epidermis.
- Mites. They are a large group of ectoparasites, which usually live in the skin and feed on debris such as keratinocytes (cells dead) or secretions.
- Mistletoes. They are parasitic plants that usually lodge in several species of trees in areas of Europe, America Y Africa.
- Termites. They are insects that usually lodge in trees and in wood used for the construction of houses. They have a great capacity for destruction.
- The bacteria. They form a diverse and extensive group. They are usually found in the Water and on the earth, so they enter the body through the food and they stay in the digestive system of the animals.
- The virus. They are obligate parasites, since they cannot be considered living beings, and to carry out their functions they need to take advantage of the organism they invade. They frequently enter the body through the digestive or respiratory systems.
- Amoebas. They are endoparasites, which usually lodge in the intestines of animals. They feed on the host, so they can cause malnutrition and serious illnesses.
- The worms. They tend to lodge in various parts of the host's body and can take away its nutrients.
Social parasitism
Social parasitism refers to the type of association that some animal species make to obtain some benefit, but that does not directly impact their organism or biology, but rather benefits them in their social development. For example, some birds lay their eggs in the nests of other species of birds, so that the latter raise them.
Social parasitism within a community from persons exceeds the strictly biological point of view mentioned above and refers to a derogatory association, in which the parasite attempts against the ethics and the moral that predominates in the society of the host (that is, it does not obtain directly biological benefits). For example, in some regions individuals who live with and with their parents until advanced adulthood are considered “parasites”, obtaining the benefit of a life of comfort and fewer worries.