Are encrusters, attaching themselves permanently to a hard substrate.The most common, acorn barnacles (Sessilia), are sessile, growing their shells directly onto the substrate.
Barnacles are shrimp-like arthropods that swim free when young then glue themselves to some hard surface and spend the rest of their life kicking food into their mouths with their feather-like legs. No.   Additional Info: According to the IUCN Red List, there are only two Barnacle species listed out of what is generally believed to around 900 species living today. As the barnacle larvae are so tiny, they float around with the plankton in the water. Once the barnacle is older and has it's tough outer shell, few predators can actually eat it. Humans are known to eat goose barnacles (the only edible species of barnacle) in parts of Europe like Spain and Portugal. Barnacles are often seen on crabs, whales, boats, rocks and on the shells of sea turtles. Although some species of barnacle are parasitic, most barnacle species are harmless, because they are filter feeders and do not interfere with an animal's normal diet and do not harm that animal that they live on in any way. Barnacle is a small but a hardy saltwater animal belonging to Arthropoda phylum along with being put in the class Crustacea and the order Cirripedia. Barnacles are usually found attached to ships, rocks, wharves, marine animals and to other hard surfaces. Acorn barnacle, Brown Buckshot barnacle, Goose barnacle and Thatched barnacle are some common types of barnacle. Barnacles are closely related to lobsters and crabs as they too have a hard outer cover.  Description [edit]. Barnacles are encrusters, attaching themselves permanently to a hard substrate. The most common, acorn barnacles (Sessilia), are sessile, growing their shells directly onto the substrate. The order Pedunculata ( goose barnacles  and others) attach themselves by means of a stalk. Barnacles are exclusively marine, and tend to live in shallow and tidal waters, typically in erosive settings. They are sessile (nonmotile) suspension feeders, and have two nektonic (active swimming) larval stages. Around 1,220 barnacle species are currently known. The name Cirripedia is Latin, meaning curl-footed Goose barnacles (order Pedunculata), also called stalked barnacles or gooseneck barnacles, are filter-feeding crustaceans that live attached to hard surfaces of rocks and flotsam in the ocean intertidal zone.  Barnacles feed on plankton they sweep from the water with their fan-like feet. Their main predators are whelks --snails that envelop the barnacle's cone and force the valves open. The blue mussel is a competitor for space, possibly outgrowing and smothering barnacles. That's where barnacles live, peeking out only when water covers them so they can filter food into their homes. This barnacle zone is the highest of the intertidal zones. Although they may look like mollusks with their shell-like covering, barnacles are actually crustaceans, related to lobsters, crabs and shrimp. They look like tiny shrimp in their larval stage, where they swim as members of zooplankton in the ocean Barnacles attach themselves to animals when they are very young and in the larvae stage of their lives. Once the baby barnacle has effectively glued itself to something hard, a thin layer of flesh wraps around the barnacle and an outer shell is produced. Barnacles are often seen on crabs, whales, boats, rocks and on the shells of sea turtles. Although some species of barnacle are parasitic, most barnacle species are harmless, because they are filter feeders and do not interfere with an animal's normal diet and do not harm that animal that they live on in any way.
http://www.answers.com/Q/What_are_barnacles http://a-z-animals.com/animals/barnacle/ http://animalsadda.com/barnacle/ https://en.wikipedia.org/wiki/Barnacle https://en.wikipedia.org/wiki/Goose_barnacle http://www.whoi.edu/science/B/people/kamaral/Barnacles.html http://a-z-animals.com/animals/barnacle/
what are barnacles