Familia Carinariidae

Family Carinariidae Fischer, 1883

In Carinariidae, with three genera (Carinaria, Cardiapoda, Pterosoma), the calcareous aragonite shell is only coiled in the first whorls, the body whorl is straight and the whole shell is small relatively to the the soft parts. Strong transverse waves have developed to give the shell some rigidity. This wavy structure closely resembles the wavy shells in pteropods such as Hyalocylis and Clio recurva. The shell is not so much reduced but the body is strongly enlarged and retraction into the shell is no longer possible. The animals always swim with the shell turned downward as in Carinaria lamarcki. The operculum is lost after metamorphosis. The anatomy of Carinaria resembles that of the atlantids. The gills are large and always hang out of the mantle aperture. The musculature is different from that in Atlantidae; the columellar muscle between the visceral nucleus and wing is reduced. The attachment to the shell is weak so that in captured specimens the shell is usually detached, but a very strong body muscle-sheet has developed. In the females the penis and spermatophores are absent. In males a penis is normally found at the right side between the body and fin with the seminal groove connecting the sexual aperture and the penis. The shape of the visceral parts reflects the shape of the shell.
In Cardiapoda placenta the shell is so strongly reduced that the visceral nucleus does not reflect its shape. The shell consists of a protoconch with a minuscule shield of teleoconch, the whole shell is embedded in the liver. The anatomy is similar to that of Carinaria. Although the gelatinous body of Pterosoma planum is strongly flattened, its anatomy and the shell are comparable to that of Carinaria.

[3 genera]