Dentaliida
Dentaliida is an order of marine molluscs commonly known as tusk shells, tooth shells, or scaphopods. These small, elongated invertebrates are unique for their tube-shaped shells that are open at both ends. Found in a wide range of marine environments, they play an important role in benthic ecosystems.
Characteristics
Dentaliida possess a number of distinctive features that distinguish them from other mollusc groups. Their shells are typically slender, curved, and tapered at one end, resembling an elephant tusk or a tooth. This shell is made of calcium carbonate and is secreted by the mantle, which is the fleshy outer layer of the body. The shell is open at both ends, allowing water to flow through for respiration and feeding.
Tusk shells are burrowing animals, using their foot to dig into the sediment. They are carnivores, feeding on small organisms, such as foraminifera and diatoms, that they capture using a specialized feeding apparatus called a captaculum. This tentacle-like structure extends from the anterior end of the shell and helps capture prey.
Environments
Dentaliida are found in a variety of marine habitats, ranging from shallow coastal waters to the deep sea. They are often found in soft sediments, such as sand, mud, and gravel. They are particularly abundant in areas with strong currents, which bring them a steady supply of food. Some species can also be found in rocky or coral reef environments.
Classification
The order Dentaliida contains a single family, Dentaliidae, which is further subdivided into a number of genera. Some of the most common genera include:
- Dentalium
- Fissidentalium
- Cadulus
- Antalis