[Symbiosis: close and long-term interaction between two biological species; relationship in which both species benefit from the other]
     One of the most intriguing of all symbiotic alliances is that of the clownfish and the sea anemone.    Clownfish are very poor swimmers by nature, and therefore are an easy target for any predator.  Sea anemones, though the clownfish's protector, are generally dormant/neutral creatures. Their tentacles do, however, have nematocysts, which sting  when provoked (this is very rare),  but the anemone is incapable of harming the clownfish.  Marine biologists have studied this pair since the early 19th century, but still have not come to a certain understanding as to why the anemone doesn't sting the clownfish.

[Parasitism: relationship between two biological species in which one benefits at the expense of the other]
     Within parasitism is a relationship known as social parasitism.  This is when the parasite takes advantage of interactions between its host and one of the host's symbiotic partners.  For example, Pseudoatta ants are the parasites to "cuckoo" birds (these birds have a symbiotic relationship with another organism as well).  The ant and the bird will have a symbiotic alliance for over half of the bird's life-span, and then the ant detaches from the bird and takes the bird's symbiotic partner away.  Ultimately, while the bird was giving of itself as a host, the greedy parasite used and harmed the bird to join with another organism.

[Please know, this post is a parallel to very common relationships in life, especially the changes in a relationship that occur.  Sorry if you were excited that I had genuine interest in Marine Biology.]

**5/12/10 - I take back this post.  I must have been in a weird mood.