Why do sponges seem to represent a dead end in evolution?

General Characteristics: The parazoa represent the lineage closest to Protists, the multicultural organisms that gave rise to the animal kingdom. ... read more

Sponges are an entire phylum. Chordata is a phylum, containing all the Classes of vertebrates: fish, amphibians, reptiles, birds, and mammals. read more

Sponges do not have a coelom. A coelom is the cavity within the body in which the intestines, lungs, heart, kidney, etc., are located, and it is sealed off from the outside world. The body cavity of sponges is large, it is open to the outside world, and it enables the sponge to consume food (Dawkins 2004). read more