Divided Caecum
Caecum sepimentum
Protoconch planispiral, of about 2 whorls, smooth and transparent, with a small demarcation rim separating it from the teleoconch. Teleoconch slightly tapering, curved and crossed by 20-25 raised varices. Varices and interspaces of equal size. Longitudinal microscopic lines evident. Septum discoidal, low under the cutting plane with traces of temporary septum. Aperture circular, with a terminal swelling of 4-5 rings. Operculum corneous, light brown; external surface with 3-4 spiral small rings; the internal surface, in profile, stair-likes shaped (3 steps), showing a sunken nucleus. Colour dark brown in fresh specimens with periostracum, white in the beached ones. Length to 2.0 mm and diameter 0.4 mm.
Morphology
The caecids have taxonomical powerful characters of the protoconch and teleoconch, as well as operculum. The protoconch may be regularly coiled, planispiral or terminally spiral with straight subsequent tube. The teleoconch may be deciduous and shed early growth sections, including protoconch, and teleoconch parts. The shear point of the teleoconch have pronounces species specific characters including the septum which may have a spike or bulge (mucro). The operculum has useful characters on the internal side in particular. The anatomy and associated characters have not been sufficiently documented to establish whether comparative anatomy is useful taxomomically.
Evolution
Caecid fossils are know from Cretaceous Tethys Sea deposits, Late Cretaceous deposits of the Americas as well as Late Eocene-Early Oligocene rocks of the Antarctic Peninsula.
Behaviour
Caecids are microphagous feeders like other truncatelloideans, many of which graze biofilms.
Method of reproduction
The groups have separate sexes and the copulation is internal with a male penis and female bursa copulatrix. Egg capsules are simple spherical structures covered in sand grains and microalgae. The larvae have pelagic development.
Habitat
Marine
The generally live in shallow water, even intertidally, in association with sea grass, algae, rocks, pebbles or even interstitially in gravel.
Distribution
Indo-west Pacific
Life Cycle
Benthic adults, most likely free swimming larvae
| Kingdom: | Animalia |
|---|---|
| Phylum: | Mollusca |
| Class: | Gastropoda |
| Subclass: | Caenogastropoda |
| Order: | Littorinimorpha |
| Superfamily: | Truncatelloidea |
| Family: | Caecidae |
| Subfamily: | Caecinae |
| Genus: | Caeccum |
| Species: | sepimentum |
| Name Published Year: | 1868 |
|---|---|
| Scientific Name Authorship: | Folin |
| Commercial Impact: | None |
| Conservation Assessment: | Least Concern |
Cite this page
Western Australian Museum Collections https://museum.wa.gov.au/online-collections/names/caecum-sepimentum
Accessed 9 Aug 2024
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