There are many so called relationships in nature. They may fall into many categories; Phoresis, Commensalism, Parasitism, and Mutualism. These relationships may just the tip of the iceberg. The species involved in these relationships are incredible. They aren't special alone but together, they are truly amazing.
Phoresis is an individual of one species that gets a free rider on an individual. We see this a lot in mites on other insects. The mites actually use the insects as a means of getting around. In this form of relationship, only the rider gets any benefit. Other animals also fall into category as well. However, I am not going into real depth with this edition of Nature Weekend.
The next relationship that we want to look is Commensalism. In its simplest form, it's a one-sided relationship. Only one of the organisms gains benefit from the other organisms. A great example here is the relationship between Cattle Egrets and mammals such as horses or cattle. The cattle or horses are feeding in the grasslands. As they feed, the mammals stir up insects. The egrets take advantage of this by feeding on the insects. Other examples of commensalism can be found among certain species of fish and sea urchins. The fish rely on the sea urchins for protection from predators, however the sea urchin gains no benefit.
Parasitism involves the parasite and the host. Typically, the parasite gains benefit from the hosts, but the host faces harm or death from the parasite. Examples of parasites are human body lice, ticks, mosquitoes, and tapeworms. These examples are but a few types of parasites. Ticks feed on blood and as they feed may weaken the host from blood loss and also disease.
Another example is mutualism. In mutualism both species gain from their relationships. One classic example is found in termites. Termites cannot digest cellulose. Cellulose is found in the wood that the termites ingest. Termites though share their gut with a small protozoa that is able to digest the cellulose. The termite is able to better handle the cellulose found in wood. The termites provide shelter and food to the protozoa.
These examples are the primary forms of relationships found in nature. There are numerous other examples that we could look at in this article. My goal is simply to enlighten not to provide a textbook. With that said, I say goodbye.