Phylum Porifera

Phylum Porifera

Section 1

The invertebrates, or invertebrata, are animals that do not contain bony structures, such as the cranium and vertebrae. The simplest of all the invertebrates are the Parazoans, which include only the phylum Porifera: the sponges (Figure). Parazoans (“beside animals”) do not display tissue-level organization, although they do have specialized cells that perform specific functions. Sponge larvae are able to swim; however, adults are non-motile and spend their life attached to a substratum. Since water is vital to sponges for excretion, feeding, and gas exchange, their body structure facilitates the movement of water through the sponge. Structures such as canals, chambers, and cavities enable water to move through the sponge to nearly all body cells.

The photo shows sponges on the ocean floor. The sponges are yellow with a bumpy surface, forming rounded clumps.
Sponges are members of the Phylum Porifera, which contains the simplest invertebrates. (credit: Andrew Turner)
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