Question

Examine shells of cephalopods and gastropods, both modern and prehistoric, in the digital atlas website. Also use what we discussed during class about the differences between the shells of cephalopods and gastropods to answer this question (using complete sentences): How can we tell the shell of a gastropod from the shell of a cephalopod? Focus on these two characteristics: shape of coil (flat or cone-shaped), and whether there are numerous internal chambers, or just one continuous empty space inside the shell.

Answer 1

All gastropods with the exception of slugs, have hard external shells protecting their internal organs. Most gastropods have spirally coiled shells, with majority of the species exhibiting dextral coiling and a small fraction of species, with sinistral coiling.

Cephalopods are believed to be evolved from certain species of gastropods. Cephalopods generally do not have external shells but some of the species still retain an internal shell. The ancestors of cephalopods are believed to have external shell like gastropods but the modern species have evolved to possess internal shells and certain species still possess an extrenal shell. They have plainspirally coiled shell.