The approximately 8,550 living sponge species are scientifically classified in the phylum Porifera, which is comprised of four distinct classes: the Demospongiae (the most diverse, containing 90 percent of all living sponges), Hexactinellida (the rare glass sponges), Calcarea (calcareous sponges), and Homoscleromorpha (the rarest and simplest class, only recently recognized, with approximately 117 species). [Source: NOAA]
Sponges are a diverse group of sometimes common types. Glass sponges have fragile but delicate matrixes of spicules. Calcareous sponges are the only sponges with spicules made of calcium carbonate. Demosponges, that compete with coral to dominate reefs and make up 90 percent of all sponges
Types and species of sponges include Venus-flower baskets, one of the most beautiful glass sponges (See Below); bath sponges, used to make shingles; and horny sponges that you should keep away from your girlfriend. Deep sea sponges gave been found at deep sea vents and in the Southern Ocean abyss. Sponges are primarily marine, but around 150 species live in fresh water.
Sponges are found in virtually all aquatic habitats, although they are most common and diverse in the marine environment. They are particularly associated with coral reefs. Sponges are found in a wide variety of colors, shapes, and sizes and are often mistaken for plants. Scientists believe that their varied colorations may protect them from the sun’s harmful ultraviolet rays.
Websites and Resources: Animal Diversity Web (ADW) animaldiversity.org; National Oceanic and Atmospheric Administration (NOAA) noaa.gov; Fishbase fishbase.se; Encyclopedia of Life eol.org; Smithsonian Oceans Portal ocean.si.edu/ocean-life-ecosystems ; Monterey Bay Aquarium montereybayaquarium.org ; MarineBio marinebio.org/oceans/creatures; Websites and Resources on Coral Reefs: Coral Reef Information System (NOAA) coris.noaa.gov ; International Coral Reef Initiative icriforum.org ; Coral Reef Alliance coral.org ; Global Coral reef Alliance globalcoral.org ; Global Coral Reef Monitoring Network gcrmn.net
Fire sponges (Scientific name: Tedania ignis) live in the westers Atlantic Ocean from Brazil in the south to South Carolina in the north and parts of the Caribbean Sea and Gulf of Mexico. They are typically found at depths of 0.5 to two meters (1.64 to 6.56 feet) in tropical waters with a relatively slow but steady water flow. Fire sponges are found in two general habitats: at coral reefs and among red mangrove roots. Those in reef habitats hide under patches of coral rubble to avoid predation by fish. The lifespan of an individual organism is difficult to quantify because of the regeneration and asexual reproduction they engage in. [Source: Mary McCarthy, Animal Diversity Web (ADW) /=]
Fire sponges belong to the class Demospongiae, the most numerous and diverse class of sponges, with more than three quarters of all species of sponges. Fire sponges range in length from one to 30 centimeters (0.4 to 12 inches).They are poisonous, ectothermic (use heat from the environment and adapt their behavior to regulate body temperature) and heterothermic (have a body temperature that fluctuates with the surrounding environment).
For the most part, fire sponges are conspicuously bright orange in color. They are sessile (fixed in one place) and colonial (live together in groups or in close proximity to each other). The grow in low mounds extending in all directions, approximately one centimeter thick. Oscula are scattered throughout the organism. The spicules of Fire sponges are smooth with curved styles and the tylotes are straight with microspined ends. Fire sponges have spicules ranging in size from 50-270 micrometers in length and 32.-9.8 micrometers in width. The diameter of the ostial openings are 3.5-14.0 micrometers. Fire sponges can be difficult to differentiate from other species in the same family. One example of this is Tedania klausi which shares the bright orange coloring with Fire sponges. Both species have similar spicule sizes. However, they can be differentiated by the more defined volcano shaped columns with a single osculum in Tedania klausi. /=\
Fire sponges are a filter feeder consuming small and large planktonic particles. One study found the specific filtration rate of Fire sponges to be 1597 milliliters per hour per gram of tissue. It also had significantly higher filtration rates when fed a mix of different phytoplankton. Their main known predators are angel fish, cowfish, filefish, parrotfish, opisthobranch mollusks starfish and hawksbill turtles.
Fire sponges engage in seasonal breeding. The breeding season is from April to August The number of offspring ranges from 15 to 20 and the age in which they become independent ranging from 48 to 72 hours. There is no parental involvement in the raising of offspring. Demospongiae, class of of sponges of which fire sponges belong, in are capable of both asexual and sexual reproduction. The method of reproduction varies on environmental factors such as physical or biological disturbances.
Fire sponges are not a directly exploited commercially by humans but they do help humans by helping to control phytoplankton blooms. Fire sponges have not been evaluated for the International Union for Conservation of Nature (IUCN) Red List. They have no special status according to the Convention on the International Trade in Endangered Species (CITES).
Ciliated sponges (Scientific name: Sycon ciliatum) are marine sponges found world-wide, mainly in temperate regions and usually in shallow water, but occasionally at depths of more than 150 meters (500 feet). They are often observed on the underside of rocks in relatively protected areas among bryozoans, hydroids, and other organisms in reefs, coastal areas and on or near the sea bottom as well as intertidal (littoral) zones on the shores. Ciliated sponges are sometimes eaten by nudibranchs, chitons, sea stars, turtles, and some fish.[Source: Deidra Schelin, Animal Diversity Web (ADW) /=]
Ciliated sponges are elicate-looking and creamy yellow in color. According to Animal Diversity Web: Their bodies are arranged in the asconoid system, which is a simple tube with no folding of the outer body wall. They range from 1-3 centimeters in height. Hairy, needle-like spines (called spicules) cover their bodies. The spicules surrounding the osculum opening are longer than those at the base of the body. Y-shaped tetraxon calcite spicules lining the spongocoel and triactine spiclules in the walls of the flagellated chambers form the supporting skeleton of the sponge. The spicules appear to lie in a jelly called mesohyl, a structureless jelly containing archaocytes, amoeboid cells, and others. Internal flagellated tubes are responsible for water current. The tubes are arranged radially and have openings call apopyles. Apopyles open into a central cavity or the spongocoel. The spongocoel leads into the osculum, which has an adjustable diaphragm. The diaphragm is surrounded by large spicules.
Ciliated sponges are sessile (fixed in one place). They can withstand movements of water and changes in tides. The hair-like covering of the calcite spicules holds water because of capillary action. This also prevents air from entering the chambers. /=\ It is believed that the large fine spicules surrounding the diaphragm help separate the inhalent and exhalent currents. They may also prevent small predators such as amphipods, syllid worms, and polyclads from entering the spongocoel. Ciliated sponges have no special status according International Union for Conservation of Nature (IUCN) Red List and the Convention on the International Trade in Endangered Species (CITES).
Ciliated Sponge Feeding, Reproduction and Development
Ciliated sponges obtain food by filtering water through choanocytes (cells with flagellum that line the internal chambers of sponges).. Water enters the incurrent canal (openings through which water enters the body of sponges). The canal is lined with cells called pinacocytes and communicates with the flagellated chambers through small holes, the propsopyles, which open into an internal flagellated tube lined with choanocytes. Food particles are digested intracellularly. Nutrients are transported from choanocytes to other cells through amoeboids in the mesohyl. [Source: Deidra Schelin, Animal Diversity Web (ADW) /=]
Ciliated sponges are simultaneous hermaphrodites in which individuals have sex organs of both sexes and can produce both sperm and eggs even in the same breeding season. They engage in internal reproduction in which sperm from the male parent fertilizes an egg from the female parent and are iteroparous (offspring are produced in groups).
According to Animal Diversity Web: Reproduction occurs mainly sexually. The formation of female eggs and sperm occurs from choanocytes. Spermatogenesis occurs in spermatic cysts which form in the mesohyl. These cysts can form when cells of the choanocyte chamber are transformed to spermatogonia through withdrawl of their flagellum and mitosis. Sperm are released into the sea through the osculum. Choanocytes of another sponge trap sperm and retain it in a vacuole. The choanocyte then looses its collar and flagellum. The cell is now called a carrier cell. This cell migrates through the mesohyl to an ovum. The carrier cell enters the cytoplasm of the ovum. /=\
Development of the larva takes place within the parent sponge. The parent sponge nourishes the blastula by means of trophic cells that pass into the blastula. The blastula then turns inside out so the flagella project outwards. Once the amphiblastula with a hollow central cavity, the larvae is set free to swim in the sea. Once the larvae settles, the flagella are withdrawn and the cells form a central mass. A pupae is formed when the external cells flatten and serete spicules. A cavity forms that will be the first flagellated chamber and then the spongocoel. Once this cavity forms, the sponge begins to take on the shape of a cylinder. /=\
Giant Barrel Sponges
Giant barrel sponges (Scientific name: Xestospongia muta) have been called “redwoods of the reef” because their sizes,, with masses that exceed most other benthic (bottom-dwelling) invertebrates, and are also extremely long lived. Marine sponges native to tropical waters of the Atlantic Ocean and the Caribbean Sea, they are most abundant in coral reefs off the coasts of Florida, Central America, the Bahamas and Greater Antilles and are found as far south as Venezuela. Giant barrel sponges typically live at depths of 10 to 30 meters (33 to 98 feet) and have the highest density cover and greatest volume of any organism living in their environment. In some places, giant barrel sponges comprise nine percent of a coral system’s substrate. On average there are 0.2 individual giant barrel sponges per square meters in areas where they are found. [Source: Alicia Jorde, Animal Diversity Web (ADW) /=]
By some estimates the lifespan of giant barrel sponges in the wild is 2300 years. Growth of these sponges is indeterminate and damage to individuals by natural processes making dating difficult. However, research using the Tanaka indeterminate growth model has determined that giant barrel sponges can live more than 2000 years. The oldest known individual — found off the coast of Curaçao — was estimated to be approximately 2300 years old.
Giant barrel sponges reach a height, width and diameter of around one meters (3.28 feet). According to Animal Diversity Web: Their basic structure is typical of sponge species: a reticulation of cells aggregate on a siliceous scaffold composed of small spikes called spicules. Water is taken into the inner chamber of the sponge (known as the spongocoel) through ostia (small pores created by porocytes). Flagellated choanocytes line the inner chamber and help generate water currents through the sponge. They also filter out food particles, which are transported into the non-living matrix (mesohyl). Inside the mesohyl, archeocytes process the food particles. Water exits the sponge through the osculum, a hole at the top of the spongocoel. Giant barrel sponges are leuconoid sponges: water travels through a network of chambers after entering the ostia and before exiting out the osculum, increasing the choanocytes’ filtration efficiency. These sponges range in color from salmon pink to purple due to the presence of cyanobacteria symbionts (g. Synechoccus sp.). /=\
Giant barrel sponges are filter feeders. An individual may filter up to 50,000 times its own volume of water every day. Choanocytes lining the inner chambers of the sponge filter out bacteria-sized food particles. Food particles are then transported to the mesohyl, where archeocytes are responsible for processing food particles for energy. The filtration abilities and longevity of these animals make them major players in the reef community. Their main known predators of giant barrel sponges are turtles, echinoderms like starfish and sea cucumbers, nudibranchs and fish such as Sergeant majors, yellowtail snappers, parrotfish and wrasses. The songe’s protect themselves from fish with chemical defenses, including secondary metabolites such as sterols, terpenoids, amino acid derivatives, saponins, and macrolides. In the Florida Keys, giant barrel sponges are synergistically defended with microscopic glass-like rods called spicules.
Giant Barrel Sponge Reproduction and Development
Giant barrel sponges are oviparous (young are hatched from eggs) and iteroparous (offspring are produced in groups). Individuals are believed to be male or female not hermaphrodites like many other sponges and, unlike many other sponges, they reproduce sexually. They engage in external reproduction in which sperm from the male fertilizes the female’s egg outside her body and employ broadcast (group) spawning, the main mode of reproduction in the sea. It involves the release of both eggs and sperm into the water and contact between sperm and egg and fertilization occur externally. Breeding occurs at least twice a year. Spawning events have been observed during late spring, summer, and fall, depending on location. As broadcast spawners, giant barrel sponges exhibit no parental involvement in the raising of offspring other than producing eggs and sperm. [Source: Alicia Jorde, Animal Diversity Web (ADW) /=]
Giant barrel sponges are polygynandrous (promiscuous), with both males and females having multiple partners. According to Animal Diversity Web: Reproduction occurs during a synchronized spawning event in which a group of localized individuals release sperm and eggs. In one observed spawning event, eggs and sperm were released for approximately an hour. In other species of Demospongiae sponges, spawning seems to be correlated with lunar phases; one study noted giant barrel sponges spawning during the ninth night following a full moon. /=\
Eggs are found in gelatinous masses and are negatively buoyant; sperm are positively buoyant and float in a cloud in the water. Larvae are believed to be lecithotrophic and they have chemical defenses against predators. Eggs may disperse great distances from their parent sponges. Settlement may be selective; for example, a larva may settle in a deeper part of the reef if water temperatures are high.
Little is known about larval lifespan or development. Growth is highly variable; abundance and health of individual organisms can be affected by competition, predation, sedimentation, UV-light, wave surge, hurricanes, disease, and nutrition. These factors account for variability in observed growth rates that can range from 2-400 percent in one year. For example, organisms tracked in the Florida Keys occasionally show high growth rates, but growth rates in these areas tend to be low overall, with the highest rates occurring during the summer months. Spawning events have been observed in the Florida Keys throughout August and September; reports of spawning during late spring and early fall months are also known, suggesting that these sponges reproduce at least twice yearly. Although number of eggs produced per event and fecundity are not known for this species, a closely related sponge (Xestospongia bergquistia) has been estimated to produce 1.4 million eggs with a fertilization rate of 71.4 percent; giant barrel sponges may reproduce in similar numbers. Age at which sexual maturity is reached is unknown.
Giant Barrel Sponges Ecological Niches and Threats to Them
Giant barrel sponges play a particularly important ecological role because of their longevity. They filter large quantities of water, increasing water clarity, controlling algae and affecting coral populations. These sponges contribute to corals binding to substrate, facilitating reef regeneration. They provide a habitat for other invertebrates, benthic (bottom-dwelling) fish, bacteria, and cyanobacteria, which play an important role in carbon and nitrogen fixation; fixation of nitrogen by bacteria and cyanobacteria in giant barrel sponges can lead to the release of large amounts of dissolved inorganic nitrogen, providing a nutrient rich environment for algae. Humans use giant barrel sponges to humans for research, education, ecotourism and sources of medicine.
Although giant barrel sponges have not been evaluated by the International Union for Conservation of Nature (IUCN) Red List and have no special status according to the Convention on the International Trade in Endangered Species (CITES). there are a number of potential threats to their survival, including vessel groundings, marine debris, and sponge orange band (SOB) disease. SOB disease is a disease specific to sponges, beginning with lesions on the pinacoderm and leading to bleaching that can be fatal within six weeks after infection. The oldest giant barrel sponge found off the coast of Venezuela and estimated to be 2300 years old died from SOB in only a few weeks. The cause of SOB is unknown, but evidence suggests that it is a result of a change in environmental factors, particularly rising water temperatures.
Most sponge disease is reported in sponges that are under stress due to changes in environmental factors, which lead to a change in the natural microbial community associated with the sponge. Although a microbial pathogen may be the causative agent of SOB it seems more likely that changing environmental conditions are responsible for SOB. Giant barrel sponges may also undergo cyclic bleaching when symbiotic cyanobacteria leave the sponge. Cyclical bleaching affects about 25 percent of giant barrel sponges and recovery is possible over time; fatal bleaching affects only about one percent of giant barrel sponges. Damage to these sponges due to natural processes and human involvement may leave sponges unattached from their substrate but still intact, with little chance for survival. Reattachment methods have proven to be most effective at greater depths, due to protection from the storm systems that naturally disrupt shallow waters.
Glass sponges (Scientific name: Hexactinellida) are animals commonly found in the deep ocean. Their tissues contain glass-like structural particles, called spicules, that are made of silica (hence their name). Some species of glass sponges produce extremely large spicules that fuse together in beautiful patterns to form a “glass house” — a complex skeleton that often remains intact even after the sponge itself dies. The skeleton of the glass sponge, together with various chemicals, provides defense against many predators. Nonetheless, some starfish are known to feed on these rare creatures of the deep. [Source: NOAA]
Glass sponges are completely sessile (fixed in one place). Even larvae seem to display no movement, outside drifting short distances in currents. Unlike other sponges, glass sponges do not contract when stimulated. Most glass sponges live attached to hard surfaces and consume small bacteria and plankton that they filter from the surrounding water. Their intricate skeletons provide many other animals with a home.
Glass sponges occur worldwide, mostly at depths between 200 and 1000 meters (660 to 3300 feet). They are especially abundant in the Antarctic. /Glass sponge reefs were thought to have gone extinct about 40 million years ago, leaving behind giant fossil cliffs that stretch across parts of Spain, France, Germany, and Romania. In 1987, however, a team of Canadian scientists discovered 9,000-year-old living glass sponge reefs on British Columbia’s northern coast. To date, these are the only such reefs known to exist.
Glass Sponge Characteristics
According to Animal Diversity Web: All glass sponges are upright, and possess specialized structures at their bases for holding fast to the ocean floor. Most appear outwardly to be radially symmetrical; they are typically cylindrical, but may also be cup-shaped, urn-shaped, or branching. The average height of a glass sponge is between 10 and 30 centimeters, but some can grow to be quite large. A glass sponge possesses a cavernous central cavity (the atrium) through which water passes; a cap of tightly woven spicules covers the osculum in some species. Coloration in most is pale. Glass sponges most closely resemble syconoid sponges, but they differ too much internally from other sponges to be considered truly syconoid.[Source: Dan Atwater and Daphne G. Fautin, Animal Diversity Web (ADW)]
It is upon close internal examination that glass sponges can be most easily distinguished from other sponges. The skeleton of an glass sponge is made entirely of silica. These siliceous spicules are generally composed of three perpendicular rays (and therefore six points, so they are described as hexactine), and are often fused, lending glass sponges a structural rigidity not typical of other sponge taxa. /=\
Strung between the spicules is a largely syncytial network of soft body cells. Incurrent water enters the body through spaces in the syncytial strands. Within the syncytia are units functionally similar to the choanocytes found in other sponges but these units completely lack nuclei, and so are referred to as collar bodies rather than collar cells. They are flagellated, and it is the beating of their flagella that causes the current to pass through the sponge. Within the syncytia are cells functionally comparable to archaeocytes in other sponges, but these cells seem to demonstrate only limited mobility. Glass sponges lack myocytes completely, and so are incapable of contraction. While glass sponges possess no nerve structure, they seem to be able to send electrical signals across the body through the syncytial soft tissue. /=\
Glass Sponge Feeding, Reproduction and Development
According to Animal Diversity Web: Little is known about glass sponge reproduction and development. Sperm are taken into an organism with water, and then must make their way to eggs within the organism. After fertilization, the larvae are incubated for a relatively long time so they even form rudimentary spicules before being released as parenchymella larvae. These differ from other sponge larvae in lacking flagella or any other method of locomotion. Glass sponges cluster to an unusually high degree, suggesting that larvae do not drift far before settling. After a larva lands on the ocean floor, it metamorphoses, and the adult sponge begins to grow. Glass sponges are known for prolific budding. [Source: Dan Atwater and Daphne G. Fautin, Animal Diversity Web (ADW)]
Glass sponges are purely filter feeders. Sponges subsist on macroscopic detritus material, but also consume cellular material, bacteria, and nonliving particles so small they cannot be resolved with a light microscope. Small particles of edible material taken in by the current created by collar bodies are absorbed as they pass through the channels within the sponge. The collar bodies are covered with microvilli that trap food, and the food passes through vacuoles through the collar bodes and into the syncytia. Archaeocytes between the syncytial strands are responsible for food distribution and storage. The archaeocytes may also be responsible to some extent for food capture. Glass sponges seem to lack selective control over the food they ingest — any food small enough to penetrate the syncytium is ingested. Because of their lack of a continuous outer membrane and their lack of defined ostia, glass sponges lack control over how much water passes through them. It is believed that the stability of deep-water environments allows glass sponges to survive despite these shortcomings. /=\
Venus-Flower Baskets and Their Love Shrimp
Venus-flower baskets(Scientific name:Euplectella aspergillum) are one of the most beautiful glass sponges and one of the most interesting. They build their skeletons in a way that they entrap a certain species of crustacean inside for life. The two small, shrimp-like crustaceans (Stenopodidea) trapped by the sponge are of opposite sexes. They enter the sponge atrium, and, after growing to a certain size, cannot leave. A skeleton of a sponge containing the two shrimp is given as a wedding present in Japan, symbolizing the wedding vow, "Till death us do part".
Sometimes young male and female crustaceans enter the sponges while they are still larva and live out their lives inside the sponge. They feed on material brought in by the currents produced by the sponge, and eventually reproduce. Their offspring are tiny enough to escape, when they do they find new Venus flower baskets of their own to live. The pair inside the basket clean it and, in return, the basket provides food for the crustaceans through its waste. The animals eventually grow too large to escape the sponge, so they are forced to "stay put" for the rest of their lives.
Venus-flower baskets are found in the western Pacific Ocean near the Philippine Islands attached to rocky areas of the seafloor ay depths between 100 and 1000 meters (330 and 3,300 feet) and aee most common at depths greater than 500 meters (1,650 feet). Other species in their genus are found in oceans all around the world. Because Venus-flower baskets are found at such great depths information about their life is the wild is limited. It is known that are that they are sessile (fixed in one place) and benthic (bottom-dwelling) animals. They feed on microscopic organisms and organic debris filtered out of the water that flows through the sponge. Venus-flower baskets have no special status according to International Union for Conservation of Nature (IUCN) Red List or the Convention on the International Trade in Endangered Species (CITES). [Source: Beau McKenzie Soares, Animal Diversity Web (ADW) /=]
According to Animal Diversity Web: Venus-flower baskets is radially symmetric and of moderate size, ranging from 7.5 centimeters up to 1.3 meters in height. The majority are between 10 centimeters and 30 centimeters tall. The skeleton contains hexactine (six-rayed) siliceous spicules and in addition contains a latticework of fused siliceous spicules. This is where is gets the name "glass sponge" because quite literally it is made of glass, making it the most exquisite example of the class Hexactinellida, but also as precarious and as brittle as glass can be.
Surrounding this beautiful skeleton is a net of living tissue called a trabecular net, which is created by the fusion of amoeboid cells called archaeocytes. Within this trabecular net are elongated, finger-like chambers covered in choanocytes, which open into the spongocoel. Choanocytes are another class of cells, they have whip-like flagella that they vibrate in order to move water through the sponge. Both the external and internal surfaces are covered by this trabecular net. The chambers throughout the body are irregular. The end result is a funnel or vase-like shape. Hence the name, 'Venus's-Flower-Basket.' At its base, Venus-flower baskets has a tuft of elongated spicules that attaches it to the ocean bottom /=\
Image Sources: Wikimedia Commons, NOAA
Text Sources: Animal Diversity Web (ADW) animaldiversity.org; National Oceanic and Atmospheric Administration (NOAA) noaa.gov; Wikipedia, National Geographic, Live Science, BBC, Smithsonian, New York Times, Washington Post, Los Angeles Times, The New Yorker, Reuters, Associated Press, Lonely Planet Guides and various books and other publications.
Last Updated May 2023