Thecostraca

Thecostraca; Temporal range:
	A barnacle of the family Balanidae, Mission Beach, Queensland, Australia, 2001.
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Arthropoda
Superclass:	Multicrustacea
Class:	Thecostraca; Gruvel, 1905
Subclasses
	Facetotecta; Ascothoracida; Cirripedia;

Thecostraca is a class of marine invertebrates containing over 2,200 described species.^[1] Many species have planktonic larvae which become sessile or parasitic as adults.

The most prevalent subgroup are the barnacles (subclass Cirripedia), constituting a little over 2,100 known species.^[1]

The subgroup Facetotecta contains a single genus, Hansenocaris, known only from the tiny planktonic nauplii called "y-larvae". These larvae have no known adult form, though it is suspected that they are parasites, and their affinity is uncertain. Some researchers believe that they may be larval tantulocaridans. No larval tantulocaridans are currently known.^[2]

The group Ascothoracida contains about 110 species, all parasites of coelenterates and echinoderms.^[1]^[3]

The nauplius larvae (sometimes absent) can be both lecithotrophic (non-feeding) and planktotrophic (feeding), and is followed by a larval stage called the cyprid, which is always lecithotrophic. The cypridoid larvae are referred to as the y-cyprid in the Facetotecta, the a-cyprid in the Ascothoracida, and the c-cyprid, or just cyprid, in the Cirripedia.^[4]^[5]

^ ^a ^b ^c Cite error: The named reference Chan2021 was invoked but never defined (see the help page).
^ Cite error: The named reference M&D was invoked but never defined (see the help page).
^ Paul Schmid-Hempel (2011). "The diversity and natural history of parasites". Evolutionary Parasitology: the Integrated Study of Infections, Immunology, Ecology, and Genetics. Oxford University Press. pp. 18–51. ISBN 978-0-19-922949-9.
^ Glenner, H.; Høeg, J. T.; Grygier, M. J.; Fujita, Y. (2008). "Induced metamorphosis in crustacean y-larvae: Towards a solution to a 100-year-old riddle". BMC Biology. 6: 21. doi:10.1186/1741-7007-6-21. PMC 2412843. PMID 18492233.
^ Martin, Joel W.; Olesen, Jørgen; Høeg, Jens T. (July 2014). Atlas of Crustacean Larvae. JHU Press. ISBN 978-1-4214-1198-9.

[Chan2021-1] Cite error: The named reference Chan2021 was invoked but never defined (see the help page).

[M&D-2] Cite error: The named reference M&D was invoked but never defined (see the help page).

[3] Paul Schmid-Hempel (2011). "The diversity and natural history of parasites". Evolutionary Parasitology: the Integrated Study of Infections, Immunology, Ecology, and Genetics. Oxford University Press. pp. 18–51. ISBN 978-0-19-922949-9.

[4] Glenner, H.; Høeg, J. T.; Grygier, M. J.; Fujita, Y. (2008). "Induced metamorphosis in crustacean y-larvae: Towards a solution to a 100-year-old riddle". BMC Biology. 6: 21. doi:10.1186/1741-7007-6-21. PMC 2412843. PMID 18492233.

[5] Martin, Joel W.; Olesen, Jørgen; Høeg, Jens T. (July 2014). Atlas of Crustacean Larvae. JHU Press. ISBN 978-1-4214-1198-9.

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