TPO 43 integrated writing

The reading and the lecture are both about agnostids. The author of the article provides three ‎theories about how these extinct animals may have lived. The lecturer disputes all the claims ‎made in the passage. Her position is that the theories have serious weaknesses.‎

‎ According to the reading, the agnostids may have been free-swimming predators that were ‎catching smaller animals. This specific argument is challenged by the professor. She claims that ‎free-swimming predators have large and well-developed eyes, but agnostids' eyes were very ‎tiny and poorly developed, in other words, they were blind. As a result, agnostids could not be ‎predators. In addition, hunters have some sensory organs to help them, catching their prey, but ‎there is not any evidence for agnostids' specific organs in the fossil records.‎

‎ Secondly, the writer posits that the agnostids may have dwelled on the seafloor and survived ‎by scavenging dead organisms or by grazing on bacteria. The speaker, however, goes on to say ‎that seafloor dwellers cannot move fast. Their speed is slow, and they stay in one place to find ‎their food, so they belong to a small area. On the other hand, agnostids have been found in ‎multiple places, separating with long distances. This shows that agnostids moved very fast and ‎traveled easily, so they were not seafloor dwellers.‎

‎ Finally, the reading suggests that the agnostids were parasites, living on and feeding off ‎larger organisms. In contrast, the lecturer notes that the parasites' populations are not large, ‎and their numbers are too limited. On the other hand, the population of agnostids is large and ‎can be seen in fossil records, so the agnostids do not belong to parasites.‎