| Caecum | |
|---|---|
 | |
| A shell of Caecum trachea | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Gastropoda |
| Subclass: | Caenogastropoda |
| Order: | Littorinimorpha |
| Family: | Caecidae |
| Genus: | Caecum Fleming, 1817 |
| Type species | |
| Caecum tracheum tracheum Montagu, G., 1803 | |
| Species | |
See text | |
| Synonyms [1] | |
| |
Caecum is a genus of minute sea snails, marine gastropod micromolluscs or micromollusks in the family Caecidae or blind shells. [1]
This genus occurs worldwide in warm and temperate seas. Many species live in sponges, in sandy spots on reefs, or in grassy beds in shallow waters in bays and lagoons. Some species are very common and can be extremely numerous where they do occur, such as the "beautiful caecum"(Caecum pulchellum), but even they can be easily overlooked as they are so tiny. Many species are considered to be uncommon, but this assessment may be a result of lack of proper sampling.
The shells in this genus, like the others in the family, are very small with a length between 2 mm and 6 mm. Their colour is white to yellowish white and some are almost translucent. They are unusual in that the teleoconch of the adult shell is a curving tube for most of its length. In the first stage of the shell it is spiral-shaped but soon becomes cylindrical.
The shell is sealed with a permanent calcareous plug at one end and (when the animal has withdrawn into the shell) with a circular, multispiral, horny operculum at the other end, the shell aperture. The sculpture is smooth or consists of a close-set, large number of annular ridges.
These snails feed on one-celled organisms on sand grains or pebbles.
Species in the genus Caecum include: [1] [2]
