How does sponges reproduce

Since gemmules can withstand harsh environments, are resistant to desiccation, and remain dormant for long periods, they are an excellent means of colonization for a sessile organism. Sexual reproduction in sponges occurs when gametes are generated.

Sponges are monoecious hermaphroditic , which means that one individual can produce both gametes eggs and sperm simultaneously. In some sponges, production of gametes may occur throughout the year, whereas other sponges may show sexual cycles depending upon water temperature.

Sponges may also become sequentially hermaphroditic, producing oocytes first and spermatozoa later. Oocytes arise by the differentiation of amoebocytes and are retained within the spongocoel, whereas spermatozoa result from the differentiation of choanocytes and are ejected via the osculum. Ejection of spermatozoa may be a timed and coordinated event, as seen in certain species.

Spermatozoa carried along by water currents can fertilize the oocytes borne in the mesohyl of other sponges. 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. Sponges are monoecious; depending on the species, production of gametes may be continuous through the year or dependent on water temperature.

In nature, sponges are sessile as adults; however, under laboratory conditions, sponge cells are capable of localized creeping movements through organizational plasticity. They are split into the classes based on the type of spicules they have. For example, spicules may be made of calcium carbonate or a spongin fiber. Sponges live in all types of regions all over the region. They are able to thrive in most environments. Sponges can be attached to surfaces anywhere as deep as 8km in the ocean on the bottom of the ocean floor.

There are a higher number of sponge individuals and sponge species in the tropics of all regions because the water is warmer. They like to live in clearer waters over murky waters formed by currents. The murky waters may often clog the pores on the sponges so the sponge cannot get its nutrition and oxygen to survive. Sponges are important in nutrient cycles in coral reef systems. Scientists believe they may be important factors to changes in water quality, whether good or bad.

Scientists analyze how fast sponges breathe and the amount of nitrogen they release while doing so. Sponges collect bacteria when they filter the water around them. These bacteria are believed to be able to do many things. First, these bacteria may be able to create forms of nitrogen from the nitrogen gas in the water that may be nutritional for the sponge.

This process would lower excess nitrogen levels in coral reefs, also preventing harmful ecosystem changes. Scientists believe that the conversion of nitrogen gas into useful nitrogen is also beneficial to the survival of other organisms in the area. They are hoping to have discovered a pathway for the removal of excess nitrogen from coral reefs.

Sponges are strong animals with dense skeletons that are well adapted to their environments. As they may live almost everywhere, they adapt to the regions and surfaces they grow in. Certain sponge species are adapted to freshwater environments. Their skeleton types allow them to live in either hard or soft sediments. Their pores allow them to filter the water around them for food. Inside the sponge, there are flagella that create currents so their collar cells may trap the food.

Sponges may have adapted to these feeding habits from a long time ago when food sources may have been scarce. Sponges have strong structures that are able to handle the high volume of water that flows through them each day. By constricting certain of their openings, sponges are able to control the amount of water that flows through them. Sponges have been around for a very long time. The water flows through a large central cavity called the spongocoel see Figure above.

As the water flows by, specialized collar cells which are also known as choanocytes filter out food particles such as bacteria. Collar cells have tiny hairs that trap the particles. They also have a flagellum that whips the water and keeps it moving.

Once the food is trapped, the collar cells digest it see Figure below. Cells called amebocytes also help digest the food. They distribute the nutrients to the rest of the body as well. Finally, the water flows back out of the body through an opening called the osculum. The cells also expel wastes into the water for removal through the osculum. Sponges reproduce both asexually and sexually. Asexual reproduction occurs by budding. Figure below shows the sponge life cycle when sexual reproduction is involved.

Adult sponges produce eggs and sperm. In many species, the same individuals produce both. As a result, self-fertilization is unlikely to occur. What is an advantage of avoiding self-fertilization? The sponge life cycle includes sexual reproduction.

Sponges may also reproduce asexually. Sperm are released into the surrounding water through the osculum. If they enter a female sponge through a pore, they may be trapped by collar cells. Trapped sperm are delivered to eggs inside the female body, where fertilization takes place.

The resulting zygote develops into a larva. Unlike the adult, the larva is motile. It is covered with cilia that propel it through the water. As the larva grows, it becomes more similar to an adult sponge and loses its ability to swim. Sponges that live on coral reefs have symbiotic relationships with other reef species. They provide shelter for algae, shrimp, and crabs.

In return, they get nutrients from the metabolism of the organisms they shelter. Sponges are a source of food for many species of fish.