The sponge body depends on the ability to control and maintain water flow throughout the flagellated canals and round chambers depending on the type of body design the sponge has. Water brings with it oxygen, and microscopic food, and takes away carbon dioxide and nitrogenous wastes along with the sponges gametes (only sperm as egg is not released) and larvae.
Sponges like leucosolenia (asconoid type) and leuconoid sponges may pump around 22L of water per day. This is attributed to the many round chambers in the leuconoid body design.
Porocytes and myocytes are responsible for controlling the water movements. Porocytes close to keep bacteria in the water collected by the sponge for digestion. The opening of the osculum of the sponge is controlled by myocytes, such that when they contract, the osculum aperture closes, keeping water and food in. Myocytes are found in the mesohyl around the osculum. They are special cells such that they are similar to smooth muscle cells, but different because they do not contact each other and thus never form a layer like the smooth muscle cells do.
Sponges lack a nervous system. To communicate instead, they use diffusion of chemicals from cell to cell. As well as exchange of nutrients. However their reactions are slow, and local, and do not involve the entire body of the sponge.
Sponge Relationships:
Mutualistic: with autotrophic photosynthetic organisms like Zooxanthellae, cyanobacteria, algae and zoochlorella. These are harbored within the ambeocytes in the mesohyl layer mainly, or between the collagen fibers outside the mesohyl layer. The microorganisms gain amino acids obtained by the sponges from feeding on bacteria, and a home for protection. The sponges in return get a lot of carbohydrates and food. This is only for shallow water sponges.. The color of the sponge will vary depending on what it will harbor.
if zoochlorella, it is green. if cyanobacteria, it is blue or violet. if zooxanthellae, organgish brown
Another mutualistic relation: sponges growning on the carpace or claws of crab. The crab benefits by being camouflaged from his mortal enemy, the octopus. And the sponges benefit from constantly being moved throught the water and relocating to new potential food sources.
Commensal: hosting shrimps, crabs, brittle stars or starfish. The host doesnt benefit. But the organisms gain a home.
Some organisms enjoy sitting on the sponges and eating them like the sea turtles. The defense mechanism adopted is to produce secondary metabolites that prevent these organisms such as fish and crabs from getting to the sponges. These metabolites are distateful to eat, may be toxic, or slippery to the organisms. This defense mechanism is in the most advanced body design of sponges, the leuconoid architecture.
However, no matter what the sponges do, be it using spicules, or toxic chemicals, sea turtles still feed on them and love them!
Carribean sponges also called the fire sponges are red or orange in color. These cause a terrible rash to divers that come near them and allergies. And are very toxic to fish.
Spicules are used for defense as well, and are favored by sea turtles. However bath sponges are the only exception we have that lacks spicules. and instead is super soft because of the dense and coarse collagen fibers and proteins and spongin in its mesohyl.
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