Thursday, November 27, 2008
Last week I took an Ecology Exam and really drilled the concepts because I needed to do well on it. So I remember a lot of interesting examples of the topics we covered, including parasitism. An example Dr. Baines talked about that particularly stuck in my mind was about this parasitic worm like organism, whose name I can’t recall and did not write down. What I found memorable about the organism was (obviously not the name ;-) that it had the ability to dramatically alter the behavior of its intermediate host (that host which will, “harbor developmental stages of [the] parasite”). Once the parasitic worm infected its host (a snail), it caused biochemical reactions to occur within the body of the snail which resulted in the snail changing its normal behavior in dangerous ways. Instead of the snail moving carefully along the ground and keeping itself well concealed by the tall grass blades within its environment, an infected snail will crawl to the top of the blades of grass. This made the snail more visible to its main predator, local birds. The easily seen, infected snail would then be snatched up and consumed by the bird, which conveniently serves as the definitive host (the, “ host in which [the] parasite reaches maturity”) to the parasitic worm. Once the parasite reaches a certain level of maturity the bird will excrete it in its feces often onto a grassy area. There the parasite will produce offspring which may be picked up by the snail and the whole process of parasitic development is repeated.