Tunicates are a subphylum of the Chordata and occupy a diverse range of marine habitats such as shallow water, near shore, open ocean, and the deep sea.[1] Tunicates are invertebrates, and their bodies are surrounded by a tunic resembling cartilage, composed of proteins, carbohydrates, and tunicin, with thickness ranging from thin and delicate to transparent and gelatinous.[2] The three classes of tunicates are Ascidiacea, Thaliacea, and Appendicularia.[1]
Styelidae contain both colonial and solitary species, and a number of these species have intermediate morphologies.[7] For example, certain social species within the Styelidae family reproduce clonally, and others grow in large clusters that resemble social colonies; some species brood larvae, and others are solitary, free-spawning species; and some species within Styelidae exhibit direct development.[7]
Polyandrocarpa are a genus within the family Styelidae. Characteristics of Polyandrocarpa species include bilateral symmetry, colonial organization, a soft-bodied skeletal structure, i.e., invertebrates, and may possibly include an ocelli visual system. Species are filter feeders in marine benthic and shallow environments.[8]
Species
Species within the genus Polyandrocarpa include:[9]
Polyandrocarpa abjornseniMichaelsen, 1927
Polyandrocarpa abjornseni have two, long-oval gonads on each side of the body, each with six pairs of male follicles, differing from most known species of Polyandrocarpa that have short, numerous polycarp-type gonads.[10]
Polyandrocarpa anguineaSluiter, 1898
Polyandrocarpa anguinea has a known distribution of the Southeastern United States (Florida), Panama, Martinica, Southeastern Brazil, Sierra Leone, South Africa, Mauricius Island, Indonesia, Philippines, Australia, and New Caledonia.[11]
Polyandrocarpa arianaeMonniot F., 2016
Polyandrocarpa arianae has a polycarpid gonad.[12]
Polyandrocarpa polyporaMonniot F. & Monniot C., 2001
Polyandrocarpa robustaSluiter, 1919
Polyandrocarpa rollandiTokioka, 1961
Polyandrocarpa shimodensisBrunetti, 2007
Polyandrocarpa simulansKott, 1972
Polyandrocarpa sparsaKott, 1985
Polyandrocarpa triggiensisKott, 1952
Polyandrocarpa watsoniaKott, 1985
Polyandrocarpa zorritensisVan Name, 1931
Polyandrocarpa zorritensis has a known distribution of Japan, Guam, and Hawaii, with a probable geographical origin of the Western Pacific region.[11] It is a colonial species with an asexual life cycle.[13]
Habitat and distribution
Polyandrocarpa have been found in marine environments globally.[14] Species can range from shallow environments to benthic environments. For example, Polyandrocarpa zorritensis is a shallow species, whereas Polyandrocarpa arianae have been found deeper than 90 meters in the Mediterranean Sea.[15]
Polyandrocarpa have been reported in various regions, including the coasts of North America, South America, Europe, Africa, Asia, Australia, and in the Atlantic, Pacific, and Indian Oceans.[11][16]
Some species of Polyandrocarpa are invasive in certain regions. For example, Polyandrocarpa zorritensis is native to the Atlantic Ocean but is considered a threat to certain marine species in the Mediterranean Sea.[16][17]
Habitats of Polyandrocarpa species include coral reefs, estuaries, rocky or other hard surfaces, and marine benthic environments. Species attach to surfaces using an adhesive secretion.[16][18]
Species of Polyandrocarpa play an important role in marine ecosystems as filter feeders, helping to remove small particles and pollutants from the water.[19][20]
Diet
Polyandrocarpa feed on small particles and plankton.[20]
Life history
Polyandrocarpa are characterized by their small size and simple body structure. They typically form small, spherical colonies that consist of multiple individuals, or zooids, connected together.[21]
Polyandrocarpa form colonies composed of multiple individuals.[14][10]
Polyandrocarpa can have colonies with embedded zooids or separate zooids joined by basal stolons, though the majority of species within this genus do not have completely embedded zooids.[10] Each zooid has a sac-like body with two siphons: an inhalant siphon that draws in water and food particles, and an exhalant siphon that expels waste and water back into the surrounding environment.[22] An exception to this is Polyandrocarpa colligata. P. colligata has completely embedded zooids and an encrusting colony.[10]
Tunicates can reproduce both sexually and asexually. Polyandrocarpa zorritensis have the ability to reproduce via non-embryonic development (NED), i.e., asexual budding. Polyandrocarpa are capable of regenerating body parts.[23]
Some Polyandrocarpa species have adapted to high-flow environments and are tolerant to temperature and salinity changes.[24]
Uses by humans
Some species of Polyandrocarpa are also used in biomedical research due to their ability to regenerate body parts, which may have implications for human tissue engineering and organ transplantations in the future.[23]
1 2 3 Carman, Mary R. (2011). "Ascidians at the Pacific and Atlantic entrances to the Panama Canal". Aquatic Invasions. 6 (4): 371–380. doi:10.3391/ai.2011.6.4.02. hdl:1912/5294.
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