Anatinellidae Family of Duckclam Shells
Pacific Duckclam Shelll, Raeta undulata. A representative of the Anatinellidae Family of Duckclam Shells.
Phylogeny: The Anatinellidae Family of Duckclam Shells is in the phylum Mollusca. They are in the class Bivalvia, the subclass Autobranchia, the infraclass Heteroconchia, the subterclass Euheterodonta, the superorder Imparidentia, the order Venerida, and the superfamily Mactroidea. The Anatinellidae Family is one of four families in this superfamily. The Anatinellidae Family contains two subfamilies. The subfamily Anatinellinae consists of only one genus and one species. The subfamily Kymatoxinae is comprised of three genera and eleven species. Until fairly recently, both of these subfamilies were part of the Mactridae Family, so it is difficult to find information specific to this Family. The Anatinellidae Family name originates from the Latin words meaning “little duck-like”, which yields the common name duckclam.
Description: Duckclam Shells are ovate to trigonal in outline and inflated in profile. The shells are thin and sometimes translucent. They may be equilateral, longer anteriorly, or longer posteriorly. The posterior end may be narrowly or widely gaping. The posterior is often offset by a ridge or keel. The ends may be broadly or sharply rounded. These shells may be sculpted with strong commarginal undulations or riblets, or with fine striae. Inside the shell, the resilifer (spoon-shaped process at hinge) projects ventrally. These shells are white in color, with a thin periostracum. Duckclams reach a maximum of 11.0 cm (4.7 inches) in length.
Habitat and Distribution: Duckclams are found buried in sand and other medium to coarse grain substrates. They prefer bays, deeper locations and other areas of limited water movement. They live in the intertidal zone and to depths of 285 m (935 feet). Duckclams are found in subtropical to tropical waters of the Pacific Ocean and the western Atlantic Ocean. At least four species from this family are found in Mexican waters.
Natural History: Duckclams are suspension feeders that filter plankton and fine detritus from the surrounding water. In turn their predators include birds, crabs, carnivorous mollusks, sea stars, and rays. They are gonochoric and reproduce sexually, through broadcast spawning, with external fertilization. While edible, Duckclams are not the subject of large scale commercial fisheries or aquaculture.