There are many different types of sponges in the world's oceans, and, contrary to popular belief, they can be quite colorful and beautiful. Sponges come in two basic types: encrusting or free-standing. Although neither of these names are part of the true classification of sponges, it does make it a bit easier to organize them. Encrusting sponges typically cover the surface of a rock in the same manner that moss covers a rock on land. Free-standing sponges are a bit more interesting.
These sponges have more inner volume compared with their outside surface area and sometimes grow into strange shapes, often reaching gigantic proportions. Many of the free-standing sponges are well known to most people. For example, nearly everyone has heard of the barrel sponge, a large tropical sponge which sometimes grows large enough to fit a whole person inside. Equally well known are the tube sponges of the tropics, coming in nearly every color of the rainbow. The channels lead to inner chambers lined with specialized feeding cells called choanocytes or collar cells.
On each collar cell a flagellum is surrounded by a ring- like comb or collar. The beating of the flagellum draws water through the comb, where tiny particles are caught and carried down to the body of the cell to be digested.
These collar cells pump water through the entire sponge and filter out food for the sponge cells to eat. Improve this page Learn More. Skip to main content. Module Invertebrates. Search for:. Morphology of Sponges Learning Outcomes Describe the organizational features of the simplest multicellular organisms. Watch these videos to see the movement of water through the sponge body.
Practice Question Which of the following statements is false? Choanocytes have flagella that propel water through the body. Pinacocytes can transform into any cell type. Lophocytes secrete collagen. Porocytes control the flow of water through pores in the sponge body. Show Answer Statement b is false. Take an up-close video tour through the sponge and its cells. Use the Interactive Sponge Guide to identify species of sponges based on their external form, mineral skeleton, fiber, and skeletal architecture.
Try It. Skip to main content. Phylum Porifera - Advanced Sponges Sponges are considered the oldest animal phyla. Features: Asymmetrical Organized as an assemblage of different kinds of specialized cells No tissues Skeleton lacking or made of spicules Porifera fact: Many sponges can filter their entire body volume in less than one minute.
Word Bank Collagen: the main structural protein of the various connective tissues in animals; sponges, like all animals have collagen. Collar cell or choanacyte: these cells line the interior of the sponge.
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