Question

During classroom discussion a student said that sponges are more complex than cnidarians. Do you agree with him. Justify.

Answer 1

Sponges are less complex because they are just made of individual cells. There is no level of organization past cells in sponges. Cnidarians, on the other hand, have tissues, a higher level of organization. Tissues allow for some forms, like box jelly fish, to have eyes (this is just one of many advantages of tissues). Cnidarians' level of organization stops there though, they have no organs (heart, brain, etc.).

Sponges do not have true tissues. They are more of a conglomeration of cells that happen to work together. If you squeeze a living sponge through a cheese cloth the cells could re-congregate and reform a living sponge.

Cnidarians have two true tissue layers and therefore the cells cannot survive long on their own. If you squeeze a Cnidarian through a cheese cloth it would die. Cnidarians do also have the beginnings of a nervous system in the form of a nerve net.