Question

The elephant tusk shell can be classified under which of the following categories?
A. Dentalium
B. Nautilus
C. Limax
D. Octopus

Answer 1

Hint: The scientific name of the genus Dentalium comes from the Latin word ‘dentis’ which means tooth, based on the tooth or tusk-shaped form of these mollusks.

Complete answer: Dentalium is a genus of the family Dentaliidae.
It is a large genus with tusk shells, tooth shells, and marine scaphopod mollusks.
The family Dental Iid is also known as the elephant tusk shell as it looks roughly like an elephant tusk.
So, the answer is A, i.e., Dentalium

Additional information:
Scaphopods possess a radula and a frontal proboscis. The head is not completely reduced. Gills are not present in scaphopods. Water is sucked into the rear end of the mantle cavity by the movement of cilia. It gets depleted from oxygen and loaded with carbon dioxide then it leaves the mantle cavity in the same way. Scaphopods do not feed by filtering the water, they catch their prey with the captacula, thin tentacles with sticky ends. In the ocean, scaphopods feed on the smallest creatures, like the one-celled Foraminifera. After the scaphopods catch foraminifera, the captacula transports it into the scaphopod's mouth. Before digesting the contents in the stomach using digestive fluids from the finger-shaped protrusions of the main digestive gland, the scaphopods cracks the calcareous shell of foraminifers with its radula. The blood circulation is completely free. The blood is not being pumped by heart action, but by foot contractions. Kidney and gonads have a common exit, it can open into the mantle cavity as well as into the intestine. Scaphopods have separate sexes. After external fertilization, their development passes a planktonic larval stage of the trochophore larva. After metamorphosis, young cephalopods are seen.

Note: Here, the cephalopods are the tusk shell or the tooth shell of the elephant. The shells of scaphopods can be crafted into bracelets and necklaces and can be used for commercial purposes.