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Class Demospongiae
(contains 90% of all sponge species, including the most common and familiar forms)


Sponges are the most primitive of the multicellular invertebrates. They lack a mouth and gut. The bodies are organized around a system of water canals. Sponges feed, breath, reproduce, and excrete by means of pumping water through their body. Their size is correlated to ocean current velocity and other factors such as availability of space and inclination of the substrate. A skeleton of organic spongin (type of protein) fibers, or siliceous or calcareous spicules, or a combination of both provides support. They vary widely in coloration (red, orange, blue, yellow, purple, etc.) and the spicules occur as many different shapes. These traits are helpful in identifying the sponge species.

Size: The sizes are very diverse. Some sponges can be less than a centimeter thick, covering or forming a crust on the surface of some object (encrusting sponges), whereas other upright forms can measure more than a meter.

Range and Habitat

Most species are marine and are found at all depths.

Natural History

Many animals use sponges for shelter. Sponges are a source of food to other invertebrates such as nudibranchs, chitons, and sea stars, and to sea turtles and tropical fishes.

Research on the biochemical products produced by sponges indicates its potential use as a source of pigments, steroids, and antibiotics.

Text by Patricia Beller

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