Gooseneck barnacles

Pollicipes polymerus is attached to rocks or other objects by a strong, rubbery stalk, the peduncle, which is up to 10 centimetres (4 in) long. It has a muscular interior and the leathery surface is covered in bands of minute spiny scales on short stalks. The capitulum, at the end of the peduncle, is up to 5 centimetres (2 in) long and contains the rest of the body including all the limbs and other appendages except the first pair of antennae. The outside of the capitulum bears five strengthening calcareous plates corresponding with the plates that protect an acorn barnacle. The largest of these is the carina, on the morphologically dorsal side of the capitulum, with a pair of smaller scuta and terga on either side below. Further calcification occurs from other centres on the capitulum with the formation of many small scales. The thoracic crustacean appendages are modified into feather-like cirri. They project through the aperture at the end of the capitulum and are used for feeding