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Semibalanus balanoides
Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Crustacea
Class: Thecostraca
Subclass: Cirripedia
Infraclass: Thoracica
Darwin, 1854
Orders [1]

Thoracica is an infraclass of crustaceans which contains the most familiar species of barnacles found on rocky coasts, such as Semibalanus balanoides and Chthamalus stellatus . They have six well-developed limbs, and may be either stalked or sessile. The carapace is heavily calcified. The group includes free-living and commensal species. [2]


This article follows Chan et al. (2021) and WoRMS in placing Thoracica as an infraclass of Thecostraca and in the following classification of thoracicans down to the level of family: [3] [4]

Infraclass Thoracica Darwin, 1854
Superorder Phosphatothoracica Gale, 2019
Order Iblomorpha Buckeridge & Newman, 2006
Family Iblidae Leach, 1825
Family Idioiblidae Buckeridge & Newman, 2006
Order †Eolepadomorpha Chan et al., 2021
Family †Eolepadidae Buckeridge, 1983
Family †Praelepadidae Chernyshev, 1930
Superorder Thoracicalcarea Gale, 2015
Order Balanomorpha Pilsbry, 1916
Superfamily Balanoidea Leach, 1817
Family Balanidae Leach, 1817
Family Pyrgomatidae Gray, 1825
Superfamily Chthamaloidea Darwin, 1854
Family Catophragmidae Utinomi, 1968
Family Chionelasmatidae Buckeridge, 1983
Family Chthamalidae Darwin, 1854
Family Pachylasmatidae Utinomi, 1968
Family Waikalasmatidae Ross & Newman, 2001
Superfamily Coronuloidea Leach, 1817
Family Austrobalanidae Newman & Ross, 1976
Family Bathylasmatidae Newman & Ross, 1971
Family Chelonibiidae Pilsbry, 1916
Family Coronulidae Leach, 1817
Family Tetraclitidae Gruvel, 1903
Superfamily Elminioidea Chan et al., 2021
Family Elminiidae Foster, 1982
Superfamily †Pachydiadematoidea Chan et al., 2021
Family †Pachydiadematidae Chan et al., 2021
Order Calanticomorpha Chan et al., 2021
Family Calanticidae Zevina, 1978
Family †Cretiscalpellidae Buckeridge, 1983
Family †Titanolepadidae Gale & Sørensen, 2015
Order Pollicipedomorpha Chan et al., 2021
Family Lithotryidae Gruvel, 1905
Family Pollicipedidae Leach, 1817
Family †Zeugmatolepadidae Newman, 1996
Order Scalpellomorpha Buckeridge & Newman, 2006
Superfamily Lepadoidea Chan et al., 2021
Family Heteralepadidae Nilsson-Cantell, 1921
Family Lepadidae Darwin, 1852
Family Malacolepadidae Hiro, 1937
Family Poecilasmatidae Annandale, 1909
Family Rhizolepadidae Zevina, 1980
Superfamily Neolepadoidea Chan et al., 2021
Family Neobrachylepadidae Newman & Yamaguchi, 1995
Family Neolepadidae Yamaguchi, Newman & Hashimoto, 2004
Family Neoverrucidae Newman, 1989 in Hessler & Newman, 1989
Family Probathylepadidae Ren & Sha, 2015
Superfamily Scalpelloidea Chan et al., 2021
Family Scalpellidae Pilsbry, 1907
Family †Proverrucidae Newman, 1989 in Hessler & Newman, 1989
Order Verrucomorpha Pilsbry, 1916
Family Verrucidae Darwin, 1854
Family †Eoverrucidae Gale, 2020
Order †Archaeolepadomorpha Chan et al., 2021
Family †Archaeolepadidae Gale, 2019
Family †Myolepadidae Gale, 2015 in Gale & Sørensen, 2015
Family †Stramentidae Withers, 1920
Order †Brachylepadomorpha Withers, 1923
Family †Brachylepadidae Woodward, 1901

Related Research Articles

Barnacle Infraclass of crustaceans

A barnacle is a type of arthropod constituting the subclass Cirripedia in the subphylum Crustacea, and is hence related to crabs and lobsters. Barnacles are exclusively marine, and tend to live in shallow and tidal waters, typically in erosive settings. They are sessile (nonmobile) and most are suspension feeders, but those in infraclass Rhizocephala are highly specialized parasites on crustaceans. They have four nektonic larval stages. Around 1,000 barnacle species are currently known. The name "Cirripedia" is Latin, meaning "curl-footed". The study of barnacles is called cirripedology.

Thecostraca Subclass of crustaceans

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

Balanidae Family of barnacles

The Balanidae comprise a family of barnacles of the order Balanomorpha. As a result of research published in 2021 by Chan et al., the members of the family Archaeobalanidae were merged with this family.

Balanomorpha Suborder of barnacles

The Balanomorpha are an order of barnacles, containing familiar acorn barnacles of the seashore. The order contains these families:

Calanticidae Family of barnacles

Calanticidae is a family of acorn barnacles in the order Calanticomorpha. There are about 12 genera and more than 60 described species in Calanticidae.

Chthamaloidea Superfamily of barnacles

The Chthamaloidea are a subdivision of Balanomorpha proposed by Newman and Ross to include barnacles with shell wall composed of rostrum, carina, and one to three pairs of latera, rarely supplemented with one or more whorls of basal imbricating plates. The rostrolatus enters the sheath, but rarely fuses with the rostrum, as in the three higher superfamilies. Shell plates are simple in construction, solid, and incorporate organic chitin between carbonate layers. Opercular plates are deeply interlocked, and in some genera, may become concrescent with age. Soft part morphology includes concave labrum without notch in the central part. Cirrus III more resembles Cirrus IV than II, or may be intermediate in structure. Caudal appendages present in some species.

The Catophragmidae are a family of barnacles in the superfamily Chthamaloidea with eight shell wall plates, surrounded by several whorls of imbricating plates. The basis is membranous.

<i>Heteralepas</i> Genus of barnacles

Heteralepas is a genus of goose barnacles in the family Heteralepadidae.

<i>Paralepas</i> Genus of barnacles

Paralepas is a genus of goose barnacles in the family Heteralepadidae.

Multicrustacea Superclass of crustaceans

The clade Multicrustacea constitutes the largest superclass of crustaceans, containing approximately four-fifths of all described crustacean species, including crabs, lobsters, shrimps, woodlice, prawns, krill, barnacles, crayfish, copepods, amphipods and others. The largest branch of multicrustacea is the class Malacostraca.

Scalpellidae Family of barnacles

Scalpellidae is a family of acorn barnacles in the order Scalpellomorpha. There are about 25 genera and 220 described species in Scalpellidae.

Verrucidae is a family of asymmetrical sessile barnacles in the order Verrucomorpha. There are about 14 genera and more than 90 described species in Verrucidae.


Scalpellomorpha is an order of acorn barnacles in the class Thecostraca. There are about 11 families in 3 superfamilies and more than 450 described species in Scalpellomorpha.

Lithoglyptida is an order of barnacles in the class Thecostraca. There are 2 families and more than 40 described species in Lithoglyptida.

Iblomorpha is a small order of barnacles in the class Thecostraca. There are only two families and about eight described species in Iblomorpha.


Calanticomorpha is an order of acorn barnacles in the class Thecostraca. There are 3 families and more than 90 described species in Calanticomorpha.


Pollicipedomorpha is an order of pedunculated barnacles in the class Thecostraca. There are 3 families and more than 30 described species in Pollicipedomorpha.


Verrucomorpha is an order of asymmetrical sessile barnacles in the class Thecostraca. They are typically found in deeper and deep-sea habitats. There are 2 families and more than 100 described species in Verrucomorpha.

<i>Verruca</i> (barnacle)

Verruca is a genus of asymmetrical sessile barnacles in the family Verrucidae. There are about 20 described species in Verruca, around half of them extinct.


  1. WoRMS (2019). Thoracica. Accessed at: on 2019-01-16
  2. Robert D. Barnes (1982). Invertebrate Zoology. Philadelphia, PA: Holt-Saunders International. p. 706. ISBN   978-0-03-056747-6.
  3. Chan, Benny K. K.; Dreyer, Niklas; Gale, Andy S.; Glenner, Henrik; et al. (2021). "The evolutionary diversity of barnacles, with an updated classification of fossil and living forms". Zoological Journal of the Linnean Society. doi: 10.1093/zoolinnean/zlaa160 .
  4. "World Register of Marine Species, genus Dosima" . Retrieved 2021-08-24.