GENERAL HISTOLOGY

Detailed explanation-1: -Answer and Explanation: The main similarity between echinoderms and cnidarians is that they are aquatic animals. The vast majority of both groups live in the ocean, though there are a few freshwater cnidarians. The fact that they can only be found in the ocean is actually a defining trait for echinoderms.

Detailed explanation-2: -One trait invertebrates like the sponge and tarantula share is lack of a backbone. In fact, they don ‘t have any bones at all. These are defining traits of all invertebrates.

Detailed explanation-3: -Cnidarians lack organs. This means that they do not have respiratory or circulatory systems. Like the cells in sponges, the cells in cnidarians get oxygen directly from the water surrounding them.

Detailed explanation-4: -Porifera, Cnidaria, and Ctenophora are the most primitive clade of metazoans. They distinguish themselves from the other metazoans by their lack of bilateral symmetry. Inside their clade, each phylum is clearly distinguished by its general features.