What is a parasite?


A parasite is an organism that benefits at the expense of another organism. Most parasites are small and cannot be seen, while others are bigger and will be seen as soon as they attach. “How come parasites are not considered predators?” It’s because parasites do not kill their host for an extended period of time while predators kills their pray straight away. Parasites reduce the biological fitness by changing its behavior, adding secondary sexual characteristics or castrating the host. There are two types of parasites: obligates (totally depends on the host to complete its life cycle) and facultative (does not depend on a host to complete its life cycle).
Different parasites have different ways of living. Some are social parasites and will take advantage of interactions between members of social organisms e.g. ants or termites. An example of this is a butterfly larva that looks like the ants larvae. It will either parasite on the ant’s egg/ larvae’s or act like an ant larvae to get fed by the ants. This is similar to how the brood parasite live. The species most commonly known to people that use brood parasitism is the Cockoos. They lay their eggs in other bird’s nests that will raise the Cockoo chick as its own.
There are a lot of parasites in the ocean. Fish, whales and dolphins are often seen with parasites attached to them and will stop at cleaning stations (on reefs) to get them removed by cleaners (e.g. shrimps and wrasses). They can be attached all over the body but are mostly seen on the fins and flukes, around the gills, eyes or genitals. These parasites will live off the skin and blood of the host, but does normally not affect them with more than slowing them down.
“What are parasites good for?” Parasites are more than half of the life diversity on the planet and therefore play an important part in the ecosystem. Parasites become food for cleaners and also weaken pray for predators.

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