**Commensalism  is a class of relationship between two organisms where one organism benefits but the other is neutral, there is no harm or benefit. An example of commensalism is a flatworm attaching to the horsecrab and eating the crab's food while the crab is not affected. Commensalism *Parasitism  is a type of symbiotic relationship between organisms of different species where one organism, the parasite, benefits at the expense of the other, the host.An example of parasitism is when a flea harms their host, such as a dog, by biting their skin, sucking their blood, and causing them to itch.

The flea, in turn, get food and a warm home. Parasitism *Predation is described as a biological interaction where a predator (an organism that is hunting) feeds on its prey (the organism that is attacked). Predators may or may not kill their prey prior to feeding on them, but the act of predation always results in the death of its prey and the eventual absorption of the prey's tissue through consumption.An example of predation is a lion and a zebra. The lion hunts the zebra in order for it to feed on.

Predation *Mutualism  is the way two organisms biologically interact  where each individual derives a fitness benefit. In other words, it is where two species are both benefited. An example of mutualism is the nectar-producing plants and its pollinators. While the pollinators (such as bees, butterflies, etc) help to pollinate the plant for reproduction, the plants also provide its pollinators with nectar as food, thus both sides benefit.Mutualism *Competition is an interaction between species, in which the fitness of one is lowered by the presence of another.

This means that there is competition within the two species in survival for food, water, territory, or sunlight. For example, a smaller tree will receive less sunlight than an adjacent tree which is larger than it in a rainforest. The larger tree is competing with the smaller one for the same sunlight, thus competition. Competition