Tusk Shells of the Dentaliidae Family
Two Tusk Shells of the Dentaliidae Family can be found in this website:
Phylogeny: Tusk Shells of the Dentaliidae Family are Scaphopod mollusks in the order Dentaliida. The Dentaliidae Family is one of eight families in this order. The Dentaliidae Family is fairly large. It contains no subfamilies, thirteen genera, and around two hundred thirty-three species. Shells in this family are also commonly called Tooth Shells and Dentaliids.
Description: Tusk Shells are long, narrow, tapering tubes that resemble the tusks found on elephants or walruses. They are curved and may be round, polygonal, or quadrate in cross section. The shells are open at both ends. As Tusk Shells grow from the wide anterior end, part of the narrow posterior end dissolves away. As a result, the posterior end may change in shape throughout the animal’s life. The head and foot are located at the wider end, which is the aperture. The head is simple, with no eyes, sensory tentacles, or gills. These animals absorb oxygen through their mantle. As juveniles the shell is sculpted with axial ribs. Adults are smooth or have axial striae. Most shells in this family are white to tan in color. The exterior surface may be glossy, smooth, or chalky. While most Tusk Shells in the Dentaliidae Family are small to medium in size, some species can exceed 18 cm (7.1 inches) in length.
Habitat and Distribution: Tusk Shells are found on sand or mud substrates. Some species bury fairly deeply while other are found just below the surface of the substrate. They live from just below the intertidal zone to depths exceeding 4,300 m (13,120). Dentaliids are found worldwide in temperate to tropical seas. Fifteen species from the Dentaliidae Family are found in Mexican waters.
Natural History: Tusk Shells are depositional feeders, which feed on foraminifera, mollusk larvae, other microorganisms, and detritus. They use specialized tentacles to collect their food. Their predators include crabs, gastropods, rays, and ratfish. They are gonochoric and reproduce sexually, with external fertilization. Tusk shells have long been used as shell money and jewelry by Native Americans and Mediterranean cultures.