Both the reading and the lecture several theories about how agnostids may have lived.

Both the reading and the lecture several theories about how agnostids may have lived. In the reading section, the writer contends that agnostids were free-swimming predators, seafloor dwellers and parasites; however, the professor casts doubt on reading points by indicating that each three theories have serious weakness. First of all, the writer claims that agnostids which were other types of primitive athropods could prey on smaller organisms in ocean; in contrast, the professor rejects this notion by stating that agnostids could not be predators because, predators had strong eyes to attak their praise while agnostids had poorly blinds eye. Moreover, other sensing organs could not be find in fossils to support Predators theory. In addition, the reading passage holds the view that since other types of primitive arthropods have dwelled on seafloor, agnostids may have dwelled on the seafloor too; on the contrary, the lecturer underlines the fact that sea floor species were localized and they did not have ability to move fast or far from the place where were originated. On the other hand, agnostids spread in the ocean and could move fast. Moreover, the writer mentions that agnostids were parasites because many species of modern-day arthropods were parasites; conversely, the professor indicates that agnostids could not be parasites because too many different types of agnostids' fossils found while parasites were limited in population since they killed each other.