Brent Mardell

 

                       Parasitism, Commensalisms, and Mutualism

 

An example of parasitism is in a cuckoo. The cuckoo is a broad-parasite it lays its eggs in other birds nests so that another species will care for its young. This type of parasitism is also known as ‘nest parasitism’ or ‘social parasitism’. This type of parasitism is highly- developed in the cuckoo family. In the European cuckoo cuculus camorus it has a well developed egg mimicry and when the egg hatches the young cuckoo pushes all the other eggs out of the nest as it will grow to a large size. So that the host bird doesn’t notice the extra egg one of the hosts eggs are eaten or removed. The parent would have observed the nest before laying the egg so that the egg was laid at the same time as the host’s.

 

 

  An example of commensalisms is hermit crabs with sea anemones on its shell. Hermit crabs are often seen securing sea anemones to their shells. The sea anemone has stinging tentacles which protect the hermit crab from predators such as octopuses and fish. When ever the hermit crab out grows its shell it finds a new one and transfers the anemone to its new shell. The crab benefits from the anemone as it gains more protection but the anemone doesn’t seem to benefit from being on the shell of the crab. The anemone might receive scraps of food from the crab as it is a messy eater, but it may also be in more danger as it gets moved around a lot.

 

 

 

  An example of mutualism is between the green tree ants of Australia and the caterpillar of the common oak butterfly. Usually the ants eat caterpillars, but with the common oak butterfly caterpillar they instead look after it. The ants will move the caterpillar to a safe housing of leaves for the night, defend it from predators and tend to all its needs. In return for this the caterpillar excretes honeydew from a pore on its back which the ants drink, the caterpillar also excretes amino acids for the ants. The ants benefit from the honeydew and the amino acids while the caterpillar benefits from the protection from predators. The caterpillars in the trees with out ants are more likely to fall victim to predators.