Chapter 30 - Animal Origins and the Evolution of Body Plans - 30.5 - The Root of the Animal Tree Provides Clues to Early Animal Diversification - 30.5 Recap - Learning Outcomes - Page 655: 1

Sponges lack symmetry, mobility and true germ layers. They also have no organs or complex body structures. However, since they are heterotrophic filter feeders that perform internal digestion, Porifera are still considered animals.

Sponges lack symmetry, mobility and true germ layers. They also have no organs or complex body structures. However, since they are heterotrophic filter feeders that perform internal digestion, Porifera are still considered animals.