TPO 43 Integrated Task

The author of the reading brings up the idea that fossils of agnostids do not let us know how they have lived. Afterward, the author mentions three feasible hypotheses about how they might have lived. On the other hand, the lecturer casts doubt on each of the hypotheses and contends that they have serious weaknesses.
The first hypothesis that the reading mentioned was that they might have been free-swimming predators that hunt smaller animals. The lecturer, on the contrary, believes that a typical characteristic of a free-swimming predator is that they mostly have well-developed eyes and have a spectacular vision that lets them keep track of the prey. Nevertheless, the agnostids have poorly tiny eyes, and in some cases they were blind. Therefore, this hypothesis would not be correct.
Secondly, the reading asserts that they might have been seafloor dwellers which have lived on the floor of the sea and might have lived by scavenging dead organisms. Conversely, the lecture refutes this hypothesis due to the fact that seafloor dwellers have been able to move fast and go far. But, the agnostids' fossils indicate that they have traveled far and been able to move fast because their fossils have been found in different geographical areas.
Finally, the author argues that they might have been parasites that lived on primitive fishes or even large arthropods. In the contrast, the lecture underlies this hypothesis by the fact that the population of the parasites is usually low because the larger number of parasites leads to the killing of the body of the host organism. However, the number of agnostids' fossils that have been found demonstrates that their populations have been large enough.