Polyandrocarpa

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]

The Ascidiacea class, also known as the sea squirts, are primarily sessile species that filter-feed and reproduce by budding.[3] This class contains three orders: Aplousobranchia, Phlebobranchia, and Stolidobranchia.

The order Stolidobranchia are distinguished from other tunicates due to the presence of folded pharyngeal baskets.[4] The order Stolidobranchia contains three families: Molgulidae, Pyuridae, and Styelidae.[5]

Styelidae contain both colonial and solitary species, and a number of these species have intermediate morphologies.[5] 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.[5]

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.[6]

Species within the genus Polyandrocarpa include:[7]

• Polyandrocarpa abjornseni Michaelsen, 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.[8]
• Polyandrocarpa anguinea Sluiter, 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.[9]
• Polyandrocarpa arianae Monniot F., 2016
  • Polyandrocarpa arianae has a polycarpid gonad.[10]
• Polyandrocarpa aurorae Monniot F., 2018
• Polyandrocarpa australiensis Kott, 1952
• Polyandrocarpa chendurensis Renganathan & Krishnaswamy, 1985
• Polyandrocarpa colemani Kott, 1992
  • Polyandrocarpa colemani have a large colony of zooids and a thick layer of muscles within the body wall.[8]
• Polyandrocarpa colligata Sluiter, 1913
• Polyandrocarpa durbanensis Millar, 1955
• Polyandrocarpa glandulosa Monniot C., 1987
• Polyandrocarpa gravei Van Name, 1931
• Polyandrocarpa griffithsi Monniot C., Monniot F., Griffiths & Schleyer, 2001
• Polyandrocarpa lapidosa Herdman, 1891
• Polyandrocarpa misakiensis Watanabe & Tokioka, 1972
• Polyandrocarpa oligocarpa Millar, 1970
• Polyandrocarpa ordinata Monniot C., 1983
• Polyandrocarpa pilella Herdman, 1881
• Polyandrocarpa placenta Herdman, 1886
• Polyandrocarpa polypora Monniot F. & Monniot C., 2001
• Polyandrocarpa robusta Sluiter, 1919
• Polyandrocarpa rollandi Tokioka, 1961
• Polyandrocarpa shimodensis Brunetti, 2007
• Polyandrocarpa simulans Kott, 1972
• Polyandrocarpa sparsa Kott, 1985
• Polyandrocarpa triggiensis Kott, 1952
• Polyandrocarpa watsonia Kott, 1985
• Polyandrocarpa zorritensis Van Name, 1931
  • Polyandrocarpa zorritensis has a known distribution of Japan, Guam, and Hawaii, with a probable geographical origin of the Western Pacific region.[9] It is a colonial species with an asexual life cycle.[11]

Polyandrocarpa have been found in marine environments globally.[12] 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.[13]

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.[9][14]

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.[14][15]

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.[14][16]

Species of Polyandrocarpa play an important role in marine ecosystems as filter feeders, helping to remove small particles and pollutants from the water.[17][18]

Polyandrocarpa feed on small particles and plankton.[18]

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.[19]

Polyandrocarpa form colonies composed of multiple individuals.[12][8]

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.[8] 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.[20] An exception to this is Polyandrocarpa colligata. P. colligata has completely embedded zooids and an encrusting colony.[8]

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.[21]

Some Polyandrocarpa species have adapted to high-flow environments and are tolerant to temperature and salinity changes.[22]

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.[21]