Editing Barnacle (section)

{{short description|Subclass of sessile marine crustaceans}}
{{other uses}}
{{good article}}
{{Automatic taxobox
| name = Barnacle
| fossil_range = {{fossil range|Carboniferous|Recent|earliest=Silurian}}
| image = Chthamalus_stellatus.jpg
| image_caption = ''[[Chthamalus stellatus]]''
| taxon = Cirripedia
| authority = [[Hermann Burmeister|Burmeister]], 1834
| synonyms = * Thyrostraca
* Cirrhopoda
* Cirrhipoda
* Cirrhipedia
| subdivision_ranks = Infraclasses
| subdivision = * [[Acrothoracica]] {{small|(Gruvel, 1905)}}
* [[Rhizocephala]] {{small|(Müller, 1862)}}
* [[Thoracica]] {{small|(Darwin, 1854)}}
| diversity = ~2115 species
| diversity_ref = <ref name="Chan Dreyer Gale 2021"/>
}}

'''Barnacles''' are [[arthropod]]s of the [[subclass (taxonomy)|subclass]] '''Cirripedia''' in the subphylum [[Crustacean|Crustacea]].<!--<ref name="worms"/>--> They are related to [[crab]]s and [[lobster]]s, with similar [[Nauplius (larva)|nauplius larvae]]. Barnacles are exclusively marine [[invertebrate]]s; many species live in shallow and tidal waters. Some 2,100 [[species]] have been described.

Barnacle adults are [[Sessility (motility)|sessile]]; most are [[Filter feeder|suspension feeders]] with hard calcareous shells, but the [[Rhizocephala]] are [[parasitic castration|specialized parasites]] of other crustaceans, with reduced bodies. Barnacles have existed since at least the mid-[[Carboniferous]], some 325 million years ago.

In folklore, [[barnacle geese]] were once held to emerge fully formed from [[goose barnacle]]s. Both goose barnacles and the [[Austromegabalanus psittacus|Chilean giant barnacle]] are fished and eaten. Barnacles are economically significant as [[biofouling]] on ships, where they cause hydrodynamic [[Drag (physics)|drag]], reducing efficiency.