Frog Shells of the Bursidae Family
One Frog Shell of the Bursidae Family can be found in this website:
California Frog Shell, Crossata californica.A representative of the Bursidae Family of Frog Shells.
Phylogeny: Frog Shells of the Bursidae Family are gastropod mollusks in the Littorinimorpha order. This order is large and very diverse in shape including snail-like, cowry shaped, and limpet-like. Most are marine species but some are found in freshwater or on land. They all have a twisted shell and a muscular foot that is used for movement. The key characteristic is that they all exhibit torsion, which is a process where the body twists so that the anus, gills, mantle cavity, and reproductive organs all point forward. There are sixteen superfamilies in this large order. The Bursidae Family is one of nine families in the superfamily Tonnoidea. There are no subfamilies in this family, but there are fifteen genera – Alanbeuella with one species, Annaperenna with one species, <emAspa with one species, Bufonaria with twelve species, <emBursa with eleven species, Bursina with six species, Colubrellina with one species, Crossata with three species, Dulcerana with four species, Korrigania with five species, Lampasopsis with four species, Marsupina with two species, Talisman with one species, Tritonoranella with four species, and Tutufa with thirteen species. Frog Shells receive their common name from the knobs on the shells that resemble warts that are found on frogs. These shells are also commonly referred to as Bursids.
Description: Frog Shells are heavy solid shells that are medium to large in size. They may be turbinate or fusiform (spindle-like) in shape. They have a large body whorl and a moderately high spire that is usually blunt. The whorls are rounded with strong shoulders at the suture. They are generally sculpted with spiral beads and knobs. They have axial varices on the right and left side of each whorl. These varices differ in height and thickness from species to species, with those from deeper water having thinner, wing-like varices. They have a large ovate aperture that is usually marked with a series of short ridges on both the inner and outer lips. Both lips may be flared and the outer lip thickened. The anterior and posterior canals are prominent and open. Most Frog Shells do not have a periostracum, but some have a very thin periostracum. Their operculum is corneous (made of horn-like material). Some species of Frog Shells have very colorful apertures. Frog Shells vary from less than 2.5 cm (1.0 inch) to more than 42 cm (17 inches) in height. Frog Shells resemble Triton Shells of the Cymatiidae Family, but differ in that Frog Shells have deep anterior and posterior canals at the ends of their aperture.
Habitat and Distribution: Frog Shells may be found attached to rocks, on algae, and within coral in shallow water, or in deep water on sand and mud substrates. They live as shallow as 1.0 m (3.0 feet) and to depths of 1,020 m (3,346 feet). Frog Snails are found worldwide in subtropical and tropical seas. Six species from this family are found in Mexican waters.
Natural History: Frog Shells are carnivores that prey primarily on bivalves, echinoderms and polychaeta worms. Those that feed on tube-dwelling polychaetas have an extendible proboscis and large salivary glands, which are probably use to anaesthetize the worms in their tube. They can then suck the worm out of its tube and swallow it whole. In turn they are preyed upon by crabs, fish, predatory mollusks and sea stars. Frog Snails are gonochoric and reproduce sexually with internal fertilization. The eggs are laid as a gelatinous matrix. In some species the female broods the egg mass with her foot. Frog Shells are edible and larger species are targeted by artisanal fisheries as well as small scale commercial fisheries. Their shells are also sought by shell collectors.