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Family  Ovulidae

Egg Cowries
 

 

 

 

 The egg cowries are most closely related to the true cowries, having in common an animal that encloses the shell with retractable flaps of the mantle. They differ from the true cowries by not having teeth on the inner edge of the aperture, and by encompassing a variety of shapes; some are more or less globular like the cowries, but others are drawn out at both ends into long, slender shells. There are about 160-170 species world-wide, mostly in the tropics.

All species of egg cowries live and feed on various types of corals: soft corals, sea fans, sea whips, sea pens and the horny gorgonian corals. In the tropics they and their hosts may occur intertidally, but in NSW they are restricted to the subtidal. Shell colour, size and proportions are affected by the host on which they live.

Less than a dozen species are recorded from NSW, all having a tropical distribution with a southern limit of central or northern NSW. Specimens are uncommon to rare in NSW. They are occasionally found as beach shells, with only a few observations of living animals and their hosts having been reported.

Family References:

  • Cate, C.N. 1973. A systematic revision of the recent cypraeid family Ovulidae. The Veliger 15 Supplement:1-116.

  • Cate, C.N. 1973. The Ovulidae: Replacement names for four ovulid homonyms. Veliger 16(2):238-239.

  • Cate. C.N. 1974. The Ovulidae: A key to the genera, and other pertinent notes (Mollusca: Gastropoda). Veliger 16(3):307-313.

  • Iredale, T. 1935. Australian cowries. Australian Zoologist 8:96-135.

  • Rosenberg, G. 1992. An introduction to the Ovulidae (Gastropoda: Cypraeacea). American Conchologist 20(1):4-7.

  • Schilder, F.A. & Schilder, M. 1971. A catalogue of living and fossil cowries. Memoirs Institut Royal Sciences Naturelle de Belgique, 2nd Series 85:1-246.

Identification Notes:

Ovulids differ from true cowries by not having teeth on the inner edge of the aperture. As in cowries, the outer lip folds inwards and thickens as the shell matures. The outer lip has an inner and outer edge - the inner edge is that towards the aperture. This is different to the inner lip of the aperture, which is the columellar side of the aperture.

Coverage:

In addition to the illustrated species, the following tropical species occur rarely in the north of the state.

  • Calpurnus lacteus (Lamarck, 1810). Indo-West Pacific, to Woolgoolga, NSW. Length to 19 mm.

  • Calpurnus verrocosus (Linnaeus, 1758). Indo-West Pacific to Coffs Harbour, NSW. Length to 29 mm.

  • Crenavolva striatula (Sowerby, 1828). Indo-West Pacific, to Woolgoolga, NSW. Length up to 12 mm.

  • Kuroshiovolva shingoi Azuma & Cate, 1971. Japan; eastern Australia to Port Stephens, NSW. Length to 26 mm. Known from only one specimen in NSW.

  • Margovula pyriformis (Sowerby, 1828). Northern Australia to Crookhaven, NSW. Length to 22 mm. Known from only three specimens in NSW.

  • Ovula ovum (Linnaeus, 1758). Indo-West Pacific to Solitary Islands, off Coffs Harbour, NSW. Length up to 99 mm.

  • Ovula costellata Lamarck, 1810. Indo-West Pacific to Solitary Islands, NSW. Length to 40 mm.

  • Phenacovolva rosea (Adams, 1854) (Synonym Phenacovolva nectarea Iredale, 1930). Western Pacific, to Solitary Islands, NSW. Length to 42 mm.