Giant barrel sponges are a marine species found in tropical areas of the Atlantic Ocean. They are found in highest concentrations in coral reefs off the coasts of Florida, in the Gulf of Florida, off the coast of Central America, and the Caribbean, including around the Bahamas and Greater Antilles. They are found as far south as Venezuela. (López-Legentil and Pawlik, 2009; McMurray, et al., 2008; McMurray, et al., 2010; Montalvo and Hill, 2011; Richelle-Maurer, et al., 2003; van Soest, 2013)
Giant barrel sponges are members of coral reef environments in tropical coastal locations. They are benthic animals, living at depths from 10-30 m. They have the highest density cover and greatest volume (0.2 individuals per m^2) of any organism living in their environment. (Bertin and Callahan, 2008; McMurray, et al., 2010; Shapiro, 2013)
Giant barrel sponges are called “redwoods of the reef” by some, because they may reach great sizes, over 1 m tall, with masses that exceed most other benthic invertebrates; they are also extremely long lived. 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.). (Jones, et al., 2005; López-Legentil, et al., 2008; McMurray, et al., 2008; McMurray, et al., 2010; Pechenik, 2010; Richelle-Maurer, et al., 2003)
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. (Lindquist and Hay, 1996; McMurray, 2008; Pawlik, 2012; Ritson-Williams, et al., 2005)
Individuals are believed to be dioecious and, unlike many other sponges, reproduce sexually. 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. ("Coral Spawning at Flower Garden Banks National Marine Sanctuary", 2013; Angermeier, et al., 2010; Hoppe and Reichert, 1987; Pawlik, 2008; Ritson-Williams, et al., 2005)
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% 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%; giant barrel sponges may reproduce in similar numbers. Age at which sexual maturity is reached is unknown. ("Coral Spawning at Flower Garden Banks National Marine Sanctuary", 2013; Hoppe and Reichert, 1987; López-Legentil and Pawlik, 2009; McMurray, 2008; McMurray, et al., 2008; McMurray, et al., 2010; Pawlik, 2008)
Growth of these sponges is indeterminate, making dating difficult; additionally, damage to individuals by natural and mechanical processes make it more difficult to determine average lifespan. However, recent research using the Tanaka indeterminate growth model to estimate the age of several individuals, shows that giant barrel sponges can live more than 2000 years. The oldest known individual was found off the coast of Curaçao; it was thought to be approximately 2300 years old. Threats to giant barrel sponges include vessel groundings, marine debris, and sponge orange band (SOB) disease. (McMurray, et al., 2008; McMurray, et al., 2010; Montalvo and Hill, 2011; Pawlik, 2008; Pawlik, 2012)
Sponges are sessile animals. In some regions, giant barrel sponges may comprise 9% of a coral system’s substrate; on average there are 0.2 individual giant barrel sponges per m^2. The filtration abilities and longevity of these animals make them a dominant competitor in the benthic community. (Bertin and Callahan, 2008; McMurray, et al., 2008; Montalvo and Hill, 2011; Richelle-Maurer, et al., 2003; Southwell, et al., 2008)
The home range of a giant barrel sponge is limited to the size of its body.
Sponges have no nervous system and there are no known direct communication methods between individuals. However, synchronized spawning events may imply a degree of communication between individuals, and research shows that these events may be coordinated by phases of the moon. It is unknown how giant barrel sponges perceive lunar phases or environmental conditions such as water temperature, which affects larval settlement. (Hoppe and Reichert, 1987)
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. (McMurray, et al., 2010; Pawlik, 2008; Pechenik, 2010; Southwell, et al., 2008)
The predators of giant barrel sponges are fishes, turtles, nudibranchs, and echinoids. Sponges that have been bleached of cyanobacteria are particularly vulnerable to damage by parrotfish. These animals primarily protect themselves from fish predation by 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. (Angermeier, et al., 2010; Bertin and Callahan, 2008; Jones, et al., 2005; McMurray, et al., 2010; Pawlik, 2012)
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 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. Giant barrel sponges may be affected by sponge orange band (SOB) disease; this 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. (Bertin and Callahan, 2008; McMurray and Pawlik, 2009a; McMurray, et al., 2008; McMurray, et al., 2010; Pawlik, 2008)
Although they play an important role in coral reef ecosystems, there are no direct economic benefits of giant barrel sponges to humans. (Harvey, 2013)
There are no known adverse affects of giant barrel sponges on humans; however, their filtering behavior of can impact aspects of the Caribbean marine environments. For example, large amounts of inorganic nitrogen released from these sponges can cause increased algal growth, which can affect coral health and potentially lead to the death of coral reefs. (McMurray and Pawlik, 2009a)
Although giant barrel sponges have not been evaluated by the International Union for the Conservation of Nature and Natural Resources, and are not currently considered threatened or endangered by any agencies, there are a number of potential threats to their survival. Sponge orange band (SOB) is a fatal disease, beginning with lesions on the sponge pinacoderm which spread, producing a transitional orange band and ultimately resulting in total bleaching of the sponge. 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% of giant barrel sponges and recovery is possible over time; fatal bleaching affects only about 1% 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. (IUCN, 2013; Angermeier, et al., 2010; Gilliam, et al., 2008; López-Legentil, et al., 2008; McMurray and Pawlik, 2009b; McMurray, et al., 2011; McMurray, et al., 2008)
Alicia Jorde (author), Bethel University, Jeff Port (editor), Bethel University, Jeremy Wright (editor), University of Michigan-Ann Arbor.
the body of water between Africa, Europe, the southern ocean (above 60 degrees south latitude), and the western hemisphere. It is the second largest ocean in the world after the Pacific Ocean.
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
living in the southern part of the New World. In other words, Central and South America.
Referring to an animal that lives on or near the bottom of a body of water. Also an aquatic biome consisting of the ocean bottom below the pelagic and coastal zones. Bottom habitats in the very deepest oceans (below 9000 m) are sometimes referred to as the abyssal zone. see also oceanic vent.
active at dawn and dusk
a substance used for the diagnosis, cure, mitigation, treatment, or prevention of disease
humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.
fertilization takes place outside the female's body
union of egg and spermatozoan
a method of feeding where small food particles are filtered from the surrounding water by various mechanisms. Used mainly by aquatic invertebrates, especially plankton, but also by baleen whales.
having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.
Animals with indeterminate growth continue to grow throughout their lives.
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
the area in which the animal is naturally found, the region in which it is endemic.
active during the night
photosynthetic or plant constituent of plankton; mainly unicellular algae. (Compare to zooplankton.)
an animal that mainly eats plankton
the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.
structure produced by the calcium carbonate skeletons of coral polyps (Class Anthozoa). Coral reefs are found in warm, shallow oceans with low nutrient availability. They form the basis for rich communities of other invertebrates, plants, fish, and protists. The polyps live only on the reef surface. Because they depend on symbiotic photosynthetic algae, zooxanthellae, they cannot live where light does not penetrate.
mainly lives in oceans, seas, or other bodies of salt water.
breeding is confined to a particular season
non-motile; permanently attached at the base.
Attached to substratum and moving little or not at all. Synapomorphy of the Anthozoa
reproduction that includes combining the genetic contribution of two individuals, a male and a female
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
animal constituent of plankton; mainly small crustaceans and fish larvae. (Compare to phytoplankton.)
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