tpo 43

Some controversy has been generated about how agnostides which is a group of marine animals that extinct about 450 million years ago might have lived. The reading states three possible theories about how this animal might have lived. However, the speaker argues that each of these points has a weakness.

The first point of dispute is about if agnostids were free-swimming predators. The lecturer explains that agnostids could not have hunt preys easily because free-swimming predators have a good vision ability. However, agnostids had poor developed eyes, they were not able to see very well. Thus, these marine animals could not have been free-swimming predators. By contrast, the writer is simply does not even consider these animals' vision ability.

The second controversial issue is if agnostids were seafloor dwellers. According to the professor, animals that live on the seafloor sually do not move quickly enough to inhabit a large area. Most of the time their populations are limited to certian area of the sea. On the other hand, the agnostides spearded over large distances of the seafloor. In addition, they are able to move the really high speed. Interestingly, in spite of that the text writer believes that agnostids might have been lived as seafloor dwellers.

The final point of debate is the question of if agnostids lived as parasites. The speaker asserts that parasites simply do not live in large populations because that would affect the hosted animals negatively, and it might lead to killing the host. Yet, the population of the agnostids is extermely large, and that is agaist the parasites characteristic. Despite all these potentiale rationale, the author ingores these possible explanations.