- also called chalky sponges
- have spicules largely made of crystalline carbonate
- size ranges from 1/8 of an inch to 5 inches
- usually white or drab in color
- have 6 rayed spicules
- made of silicone dioxide
- most have radial symmetry
- drab or white in color
- 4 to 12 inches long but some are up to 3 feet
- heterogeneous class
- skeletons are composed of siliceous spicules and a framework of fibers
- those with spicules and fibers most common
- those that don't have spicules and are supported by a horny framework are known as horny sponges
A freshwater sponge from class Demospongiae, wich contains 95% of all living sponge species.
There are over 5,000 sponge species. Most are marine, and live in all seas and at all depths. There are only about 150 species of sponges that live in fresh water. Sponges differ in size from a few millimeters to two meters! Certain sponges are brightly colored because their dermal cells hold pigments inside them. Many are red, yellow, orange, green, and purple. When the sponges are taken out of the water, however, the color fades quickly. The simplest and most primitive sponges are radially symmetrical, but some are shaped irregularily. They can stand erect, some are low and encrusting others may be branched or lobed in form.
