How to Identify the Phylum Porifera

Observe the animal. Any animal that moves visibly is not a sponge. Some sponges can move, but only very slowly.

Examine the animal, using a magnifying glass if necessary. Look at the general body shape. Sponges come in a variety of sizes and colors, but they all have basic, sac-like soft bodies with a hole at the top. More complex animals with mouthparts or shells aren't sponges. Branching organisms are likely to be protoctists, for example seaweeds.

Examine the skin of the animal. Sponges have numerous perforations all over their bodies. In fact, the scientific name stems from their characteristic pores.

Observe the symmetry of the creature. Sponges tend to be asymmetric, with a few showing radial symmetry. None show bilateral symmetry; i.e. the mirror symmetry seen in most higher animals, including humans.

Lay a plastic ruler next to the sponge and take a photograph to aid specific identification later. Make a mental note of where the sponge was, in particular what it was attached to and the depth.

Compare the photograph of the sponge to those in an identification key for the region. Narrowing it down by color quickly reduces the possibilities. Afterward, use size and shape to identify the genus and species.