Ascothoracida

{{Short description|Group of crustaceans}}

{{Automatic taxobox

| image = Dendrogaster sp.jpg

| image_caption = A member of the Dendrogaster genus

| taxon = Ascothoracida

| authority = {{nowrap|Lacaze-Duthiers, 1880 {{ITIS |id=621150 |taxon=Ascothoracida Lacaze-Duthiers, 1880 |accessdate=December 8, 2010}}}}

| subdivision_ranks = Orders and families 

| subdivision=

Dendrogastrida Grygier, 1987

Laurida Grygier, 1987

}}

Ascothoracida is a small group of parasitic marine crustaceans, comprising around 100 species and divided into Dendrogastrida and Laurida.{{cite book |author=Paul Schmid-Hempel |year=2011 |title=Evolutionary Parasitology: the Integrated Study of Infections, Immunology, Ecology, and Genetics |publisher=Oxford University Press |isbn=978-0-19-922949-9 |chapter=The diversity and natural history of parasites |pages=18–51 |chapter-url=https://books.google.com/books?id=OiyYhChj7GwC&pg=PA31}} They are found throughout the world on cnidarians and echinoderms.{{cite web |url=http://www.crustacea.net/crustace/www/ascothor.htm |title=Ascothoracida (Thecostraca, Maxillipoda) |author=J. K. Lowry |work=Crustacea, the Higher Taxa: Description, Identification, and Information Retrieval |date=October 2, 1999 |accessdate=December 31, 2009 |publisher=Australian Museum |archive-url=https://web.archive.org/web/20120224011851/http://www.crustacea.net/crustace/www/ascothor.htm |archive-date=February 24, 2012 |url-status=dead }} Dendrogastrida are parasites on echinoderms, and Laurida are parasites on cnidarians, except from the species Waginella Grygier, which is also a parasite on echinoderms (crinoids). Piercing and sucking mouthparts are used for feeding, and more advanced forms also absorb nutrients through a modified integument of the carapace. More basal forms are ectoparasitic, but most genera are meso- and endoparasitic. The sexes are separate, except from secondary hermaphroditic species of the Petrarcidae. In many species the larger female often have smaller males living inside her mantle cavity.[https://books.google.com/books?id=RcWgDwAAQBAJ&dq=Ascothoracida+Dendrogastrida+Laurida+echinoderms+cnidarians&pg=PA92 Parasitic Crustacea: State of Knowledge and Future Trends][https://books.google.com/books?id=61rCAwAAQBAJ&dq=Ascothoracida+echinoderms+anthozoans+dwarf&pg=PA104 Atlas of Crustacean Larvae]

Ascothoracida was previously ranked as an order within the infraclass Cirripedia (barnacles), but now both Ascothoracida and Cirripedia are considered separate subclasses. Those two subclasses, along with Facetotecta, make up the class Thecostraca.

The thorax of Ascothoracida species has six pair of biramous appendages, while the abdomen has four segments and a terminal telson with a caudal furca.{{cite book |author=D. R. Khanna |year=2004 |title=Biology of Arthropoda |publisher=Discovery Publishing House |isbn=978-81-7141-897-8 |chapter=Segmentation in arthropods |pages=316–394 |chapter-url=https://books.google.com/books?id=Hd4OEDo4gbwC&pg=PA354}} This arrangement is similar to that seen in copepods. In addition, there is a bivalved carapace, which is expanded in females.

References

{{Reflist|refs=

{{Cite web| title=World Register of Marine Species, subclass Ascothoracida

| url=http://marinespecies.org/aphia.php?p=taxdetails&id=22559

| access-date=2021-08-22

}}

{{Cite journal

| title = The evolutionary diversity of barnacles, with an updated classification of fossil and living forms

| date = 2021

| last1 = Chan | first1 = Benny K. K.

| last2 = Dreyer | first2 = Niklas

| last3 = Gale | first3 = Andy S.

| last4 = Glenner | first4 = Henrik

| last5 = Ewers-Saucedo | first5 = Christine

| last6 = Pérez-Losada | first6 = Marcos

| last7 = Kolbasov | first7 = Gregory A.

| last8 = Crandall | first8 = Keith A.

| last9 = Høeg | first9 = Jens T.

| display-authors = 4

| journal = Zoological Journal of the Linnean Society

| volume = 193

| issue = 3

| pages = 789–846

| doi = 10.1093/zoolinnean/zlaa160| doi-access = free

| hdl = 11250/2990967

| hdl-access = free

}}

{{cite book |url=http://atiniui.nhm.org/pdfs/3839/3839.pdf |title=An Updated Classification of the Recent Crustacea |author=Joel W. Martin & George E. Davis |year=2001 |pages=132 pp |publisher=Natural History Museum of Los Angeles County |access-date=2009-12-31 |archive-date=2013-05-12 |archive-url=https://web.archive.org/web/20130512091254/http://atiniui.nhm.org/pdfs/3839/3839.pdf |url-status=dead }}

}}