Furrow Shells of the Semelidae Family

Two Furrow  Shells of the Semelidae Family can be found in this website:

Phylogeny: Furrow Shells of the Semelidae Family are bivalve mollusks in the Cardiida order. Shells in this order are limited to marine environments. Order Cardiida consists of two superfamilies – Cardioidea and Tellinoidea. The Semelidae Family is one of five families in the Tellinoidea superfamily. There are no subfamilies in the Semelidae Family but there are fifteen genera – Abra with forty-nine species,  Argyrodonax with one species, Cumingia with seven species, Ervilia with nine species, Lacra with five species,  Leptomya with eleven species,  Leptomyaria with two species, Lonoa with two species, Montrouzieria with two species, Rochefortina with one species, Scrobicularia with two species, Semele with fifty-seven species, Semelina with three species, Theora with nine species, and Thyellisca with three species. Shells in this family are also commonly called Semeles and Semelids.

Description: Furrow Shells are medium to large-size clams that generally have a round to oval outline and are only somewhat inflated. The anterior is broadly rounded and the posterior is more acute or truncate. They are equivalve and may be thin or of robust construction. There is a gap between valves at the posterior end. The posterior end is marked with folds or furrows. The exterior of the shells is usually smooth or sculpted with delicate to heavy commarginal ridges. Some species also have fine radial ribs, producing a cancellate pattern. The hinge plate may be wide or narrow, and it may have one or two cardinal teeth. Furrow Shells tend to be whitish in color, though they may have brightly colored blushing, blotching, banding, or rays. These shells generally have a thin periostracum. The largest species in this family reach a maximum of 12 cm (4.7 inches) in length.

Habitat and Distribution: Furrow Shells reside on, and within,  sand and mud substrates. The live in the intertidal zone at to depths in excess of 4,000 m (13,120 feet). Furrow Shells are found worldwide in tropical to temperate seas, with some ranging well into boreal environments. There are thirty species of the Semelidae Family found in Mexican waters.

Natural History: Furrow Shells may be suspension feeders, filtering plankton and suspended organic matter from the surrounding water, or deposit feeders, which use their long siphons to gather  organic material that has settled onto the sediment. Having a long siphon allows them to bury themselves fairly deeply. They are capable of movement within the sediment, but seldom move far. They are preyed on by crabs, fish, and shorebirds. They are gonochoric and reproduce sexually, through broadcast spawning, with external fertilization. Furrow Shells are edible and some species are considered a delicacy.