Phylum Brachiopoda Brachiopoda are a phylum of trochozoan animals with hard valves on the upper and lower surfaces, as opposed to bivalve molluscs' left and right arrangement. Brachiopod valves are hinged at the back, with the front opening for feeding and closing for protection. Brachiopods can only be found in the sea, and the majority of species avoid areas with strong currents or waves. During ontogeny, brachiopod shells are formed by a set of conserved genes, including homeobox genes, which are also used to form mollusk shells. Brachia are usually found on the inner surface of the brachial valve. These brachia are the phylum's name, and they support the lophophore, which is used for feeding and respiration. All brachiopods have adductor muscles that are located on the inside of the pedicle valve and pull on the part of the brachial valve ahead of the hinge to close the valves. These muscles have both fast fibres that close the valves in an emergency and catch fibres that are slower but can keep the valves closed for extended periods of time. Articulate brachiopods open the valves by pulling on the part of the brachial valve behind the hinge with abductor muscles, also known as diductors.