What makes phylum porifera unique

Their strong skeletal structures help sponges withstand the high volume of water that flows through them each day. What is a glass sponge? Are corals animals or plants? What species live in or around coral reefs?

Early larval development occurs within the sponge; free-swimming larvae are then released via the osculum. Sponges are generally sessile as adults and spend their lives attached to a fixed substratum. They do not show movement over large distances as do free-swimming marine invertebrates.

However, sponge cells are capable of creeping along substrata via organizational plasticity. Under experimental conditions, researchers have shown that sponge cells spread on a physical support demonstrate a leading edge for directed movement.

It has been speculated that this localized creeping movement may help sponges adjust to microenvironments near the point of attachment. It must be noted, however, that this pattern of movement has been documented in laboratories, but it remains to be observed in natural sponge habitats. Privacy Policy. Skip to main content. Search for:. Phylum Porifera. Phylum Porifera Sponges lack true tissues, have no body symmetry, and are sessile; types are classified based on presence and composition of spicules.

Learning Objectives Explain the position of the phylum Porifera in the phylogenetic tree of invertebrates. Key Takeaways Key Points As larvae, sponges are able to swim, but as adults, they are sessile, spending their life attached to a substrate. Although the majority of sponges live in marine habitats, one family, the Spongillidae, is found in fresh water. Calcarea, Hexactinellida, Demospongiae, and Homoscleromorpha make up the four classes of sponges; each type is classified based on the presence or composition of its spicules or spongin.

Most sponges reproduce sexually; however, some can reproduce through budding and the regeneration of fragments. The majority of sponges are filter-feeders, but a few species are carnivorous due to the nutrient -poor environment in which they are found.

Key Terms parazoan : include only one phylum known as the sponges endosymbiont : an organism that lives within the body or cells of another organism spongin : a horny, sulfur-containing protein related to keratin that forms the skeletal structure of certain classes of sponges spicule : a sharp, needle-like piece holdfast : a root-like structure that anchors aquatic sessile organisms, such as seaweed, other sessile algae, stalked crinoids, benthic cnidarians, and sponges, to the substrate.

Morphology of Sponges Instead of true tissues or organs, sponges have specialized cells that are in charge of important bodily functions and processes. Learning Objectives Explain the various cell forms and bodily functions of sponges.

Key Takeaways Key Points Although sponges do not have organized tissue, they depend on specialized cells, such as choanocytes, porocytes, amoebocytes, and pinacocytes, for specialized functions within their bodies. The mesohyl acts as a type of endoskeleton, helping to maintain the tubular shape of sponges. Porocytes control the amount of water that enters pores into the spongocoel, while choanocytes, which are flagellated cells, aid the movement of water through the sponge, thereby helping the sponge to trap and ingest food particles.

Amoebocytes carry out several special functions: they deliver nutrients from choanocytes to other cells, give rise to eggs for sexual reproduction, deliver phagocytized sperm from choanocytes to eggs, and can transform into other cell types.

Collencytes, lophocytes, sclerocytes, and spongocytes are examples of cells that are derived from amoebocytes; these cells manage other vital functions in the body of sponges. Key Terms choanocyte : any of the cells in sponges that contain a flagellum and are used to control the movement of water spongocoel : the large, central cavity of sponges osculum : an opening in a sponge from which water is expelled mesohyl : the gelatinous matrix within a sponge.

Physiological Processes in Sponges Sponges are sessile, feed by phagocytosis, and reproduce sexually and asexually; all major functions are regulated by water flow diffusion. Learning Objectives Summarize the physiological processes of sponges. Key Takeaways Key Points Choanocytes trap bacteria and other food particles from water flowing within the sponge: in through the ostia and out through the osculum; particles are ingested by phagocytosis.

Sponges reproduce by sexual and asexual methods, which include fragmentation or budding; the production of gemmules is another asexual reproduction method, but is found only in freshwater sponges. What makes phylum porifera unique? Why are sponges successful? Why is porifera important? What makes sponges unique among animals? What is unique about sponges? What are two interesting facts about sponges?

Can sponges be alive? How many hearts does a marine sponge have? Epithelial cells form a skin-like layer on the outer surface of a sponge Fig. These cells protect and enclose the sponge; they can contract and shorten, moving the sponge body slightly. All sponges are filled with the pores that give the phylum its name. The tiny holes are actually the hollow insides of porocyte cells Fig.

Porocytes are narrow and elongated cells that connect the outside of the sponge to the inside cavity. These pores are sometimes also referred to as ostia , and they provide openings for water, which carries planktonic food and oxygen, to enter the sponge body Fig. Simple vase-like sponges have a single large top opening, called the osculum through which water leaves the sponge.

Most compound sponges have many oscula all over the body of the sponge. The oscula are surrounded by cells and are bigger than the ostia. Epithelial cells around the osculum can contract enough to close the opening, but the process is slow up to several minutes.

The inner surface of the sponge is lined with cells called collar cells , also known as choanocytes Fig. The collar is made of fine tubes surrounding a long whiplike thread called a flagellum. As flagella plural of flagellum in the collar cells move back and forth, they create a current of water that moves into the ostia and out the osculum. Several gallons of water can circulate through a fist-sized sponge in a single day, bringing in tiny food particles such as suspended bacteria, bits of plant and animal matter, and tiny drifting planktonic organisms.

As the water circulates, the fine tubes of the collar cells filter out the food particles and take them into the cells for digestion. For this reason sponges are described as filter feeders. Between the outer surface of epithelial cells and the inner surface of collar cells is a jellylike material.

In this jelly are the structures that support the sponge. There are also free-moving cells called amoebocytes Fig. During feeding, some of the particles taken in by the collar cells are passed on to amoebocytes, which carry them to other cells of the sponge. Several kinds of amoebocytes serve special functions, like producing the sponge skeleton, digesting and transferring nutrients, or reproducing themselves. The skeletal elements of the sponge are produced by the amoebocytes. The amoebocytes produce spongin , the soft fiber that forms natural bath sponges.

These sponges feel soft and springy to the touch because they have soft skeletons made of flexible fibrous spongin.