Fijian Caecum

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

Known from Fiji and now northern WA

Life Cycle

Benthic adults, most likely free swimming larvae