Feeding - The standard for proferous feeding is very simple. Water is pulled into the sponge via cilia in the thousands of little openings throughout its body. As the water passes through the sponge, the nutrients within the water, as well as the oxygen are absorbed by the many cells lining the inside of the sponge's tubular body. After everything of value to the sponge has been removed from its environment, the water is then pushed out of the sponge by the cilia, carrying away the sponge's wastes. The sponge has no organs, no dedicated respiratory system, no circulatory and no nervous system. The sponge is actually a very large clump of cooperating cells, some with specialized functions, but with no central system for controlling cellular functions. Each cell within a sponge is totipotent, meaning that any cell within the organism can become any other cell. For instance, and epidermal cell could become a sex cell if it needed to. Each sponge is an individual and there is no interaction between each sponge in an ecosystem.  There are, however, some exceptions to this basic concept of poriferous feeding. There have been recorded cases of sponges latching onto and slowly boring into various bivalves and even coral colonies. Once the sponge successfully bores through it's victim's shell, it releases some of its digestive cells into it's victim, effectively digesting its prey from the inside out. One species of sponge, Cladorhizidea, actually goes as far as to catch small crustaceans inside its body, contracting around it's prey and releasing the digestive enzymes and cells, with dissolve the prey and allow it to be fully digested by the sponge.  Movement - Sponges are not known for their adeptness at moving from place to place, however; many species have been known to move. It has been recorded in laboratory aquariums that some sponges can move up to 4mm per day under their own power. Many species of sponge can also travel by detaching itself from its footing or even a piece breaking off from the main organism, and riding the water currents until it settles down again. If the piece happens to settle on the shell of a creature such as a snail or crab, the sponge will actually attach itself and grow on the back of the organism, essentially hitching a ride and gaining access to newer feeding areas with no effort of its own.  |
