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.
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.
The Acrothoracica are an infraclass of barnacles.
Lepadidae is a family of goose barnacles, erected by Charles Darwin in 1852. There are about five genera and more than 20 described species in Lepadidae.
Elminiidae is a family of symmetrical sessile barnacles in the order Balanomorpha. There are about 5 genera and 12 described species in Elminiidae.
Calanticidae is a family of acorn barnacles in the order Calanticomorpha. There are about 12 genera and more than 60 described species in Calanticidae.
Chelonibiidae is a family of turtle barnacles in the order Balanomorpha. There are at least three genera and about eight described species in Chelonibiidae.
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.
Lithoglyptidae is a family of barnacles in the order Lithoglyptida. There are about 7 genera and more than 40 described species in Lithoglyptidae.
Malacolepadidae is a family of acorn barnacles in the order Scalpellomorpha. There are at least two genera and two described species in Malacolepadidae.
Iblidae is a family of crustaceans belonging to the order Iblomorpha. There are two genera in the family, each with its own subfamily.
Pachylasmatidae is a family of symmetrical sessile barnacles in the order Balanomorpha. There are about 10 genera and at least 30 described species in Pachylasmatidae.
Eolepadidae is an extinct family of barnacles in the order Eolepadomorpha. There are 2 genera and about 12 described species in Eolepadidae.
Lithoglyptida is an order of barnacles in the class Thecostraca. There are 2 families and more than 40 described species in Lithoglyptida.
Brachylepadidae is an extinct family of barnacles in the order Brachylepadomorpha, the sole family in the order. There are about 7 genera and more than 20 described species in Brachylepadidae.
Iblomorpha is a small order of barnacles in the class Thecostraca. There are only two families and about eight described species in Iblomorpha. In this group we find barnacles that use calcium phosphate in their shell, and species that protect themselves against predators with poison.
Eolepadomorpha is an extinct order of barnacles in the class Thecostraca. There are 2 families and about 14 described species in Eolepadomorpha.
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.
