Sponges have no organs, and obtain their nutrition from the water that is continuously flowing through them. Sponges can be found in variety of different sizes and shapes tubes, fans, cups, cones and blobs.
Sponges are omnivorous animals that obtain their nutrition from the food particles in the water. Sponges primarily eat bacteria, phytoplankton and bits out of the water. A number of sponge species are known to have a more carnivorous diet, eating small fish and crustaceans on the reefs.
Due to the abundance and variety of sponges, they are preyed upon by many animals. The fact that sponges move so slowly, if at all, means that they cannot avoid being eaten. Sea turtles, crustaceans, fish and echinoderms all prey on sponges.