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. Classification 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: 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 References Barnacles Arthropod superorders