Siphonal canal

The siphonal canal is an anatomical feature of the shells of certain groups of sea snails within the clade Neogastropoda.

[1] Siphonal canals allow for active transport of water to sensory organs inside the shell.

A study done by Vermeij found that shells that have a steep angle of their generating curve relative to their base axis (E) not do not have siphonal canals.

Curvemysella paula is specially adapted to live inside snail shells occupied by hermit crabs.

The position and location of attachment anteriorly near the final whorls of the shell is an evolutionary behavior of adult individuals which prevents removal by the host.

Euomphanilae gastropods in the genus Scalites developed siphons in the early Ordovician period (448-443 MYA); however, they are not observed in any other members of the clade.

[2] However, due to the widespread ecological contexts of gastropods with a siphonal canal, there is no consensus hypothesis or unified driver which can explain the evolution or loss of this structure.

A shell of Penion cuvieranus cuvieranus , with the long siphonal canal visible extending toward the bottom of the image, at the anterior end of the shell.