Pollicipedidae Family of Gooseneck Barnacles

One Gooseneck Barnacle of the Pollicipedidae Family an be found in this website:

Gooseneck Barnacle, Pollicipes polymerus. A representative of the Pollicipedidae Family of Gooseneck Barnacles.

Phylogeny: Gooseneck Barnacles of the Pollicipedidae Family are in the Arthropoda phylum and the Crustacea subphylum. This means that they have jointed legs and a hard exoskeleton. They are in the superclass Multicrustacea of true crustaceans. These animals are in the class Theocostra, often having a body enclosed within a bivalved carapace, and a head and abdomen that are frequently reduced. They are in the Cirripedia subclass, the Thoracica infraclass, and the Thoracicalcarea superorder. The Pollicipedomorpha order is one of five orders in this superorder and the Pollicipedidae Family is one of three families in this order. The Pollicipedidae Family is fairly small, with only three genera and seven species. The name Pollicipedidae comes from the Latin words meaning “thumb foot”, and refers to the thumb-like shape of these animals. The common name Gooseneck Barnacles comes from the mistaken idea of naturalists in the 1500’s that these barnacles turn into geese.

Morphology: Gooseneck Barnacles consist of a shell-like structure (capitulum) and a flexible stalk (peduncle) that attaches the animal to a hard surface. The capitulum encloses the head, thorax and cirri. The cirri are feathered “legs” that extend from the capitulum when the plates are opened. These cirri function as gills, absorbing oxygen from the water, and they sweep plankton and detritus toward the mouth. The capitulum is made up of five larger plates and numerous smaller plates, and is made of chitin. The plates are dull white in color. The peduncle is flexible and muscular, with a scaly exterior, that can be extended or contracted. One end of the peduncle attaches to rocks, or other hard surfaces, by a strong adhesive. Gooseneck Barnacles reach a maximum length of around 12 cm (4.7 inches).

Habitat and Distribution: Gooseneck Barnacles are found in tightly packed colonies, attached to hard surfaces, such as rocks, pilings, buoys, and wreckage. They generally reside in areas where significant completion exists for living space. Many species in this family live in the upper intertidal zone of exposed coastlines where they have to survive strong wave action and long periods of time being exposed to air.  Some species are found as deep as 400 m (1,312 feet). Gooseneck Barnacles have a limited distribution, being found only in temperate to tropical waters of the far Western Pacific, Eastern Pacific, and Eastern Atlantic Oceans. Three species from this family are found in Mexican waters.

Reproduction:  Gooseneck Barnacles are simultaneous hermaphrodites (having both male and females reproductive organs). Reproduction is sexual, with one individual inserting its penis into the mantle cavity of a nearby individual. The eggs are brooded in the mantle cavity for several weeks before being released as free-swimming nauplii. Gooseneck Barnacles pass through seven stages as free-swimming larvae before settling down on the substrate. The initial six stages, separated by molting are as nauplii (swimming with antennae-like appendages, having a single simple eye), and one stage as a cypris (a shrimp-like phase that searches for a permanent home).  They are slow growing, and can take five years to  reach sexual maturity.

Ecosystem Roles: Gooseneck Barnacles are suspension feeders. They use their cirri to filter suspended plankton and organic matter from the surrounding water. Gooseneck Barnacles feed on copepods, amphipods, barnacle larvae, small clams, polychaete worms and hydrozoans as well as detritus and algae. They are preyed upon by sea birds, crabs, and fish.