Some of the most beautiful seashells found in shallow-marine tropical waters today are those of cowries. There are about 200 living species of them in the world today (Abbott and Dance, 1992). Their morphology and vivid coloration can be very impressive. Two such species are highlighted here.
Cowries had a Late Jurassic origin in Italy, and they have been widespread since Cretaceous time. Their subsequent fossil record is extensive, including California, Oregon, and Washington (Groves and Squires, 2023).
The higher classification of cowries is:
Class Gastropoda
Order Littorinimorpha
Superfamily Cypraeoidea
Family Cypraeidae
Today, as in the geologic past, the greatest abundance and diversity today of cowries is in tropical to subtropical seas. In this blog, I focused on two very “eye-catching” species of cowries.
The first of these two species is Mauritia mauritiana (Linnaeus, 1758), which is a common cowrie. Its shell, which can be up to 11 cm in length, has an ovate-humped shell, with a slightly concave base bearing coarse teeth in the aperture. The dorsum (upper surface) of its shell has a brownish color with scattered light spots. The shell margins are dark brown. The lower surface [= the base] is black to brown. The shell surface is glossy and strongly reflects light. Photography of specimens is difficult because of reflections off this very glossy shell. This cowrie is common and lives in the tropical Indo-Pacific region (e.g., east Africa, Indian Ocean, western Pacific, western and northern Australia, and the Philippines, and well as Hawaii. It prefers the low-intertidal zone (approximately 1 to 8 m depth) along wave-washed basalt cliffs where it hides under stones and in crevices.
The other species highlighted in this blog is Umbilia hesitata (Iredale, 1916), an uncommon species restricted to eastern and south-eastern Australia. Its shell, which can be up to 12 cm in length, has a noticeably inflated spire area that is noticeably sunken. The dorsum has a quite variable color, namely, brownish mottled with scattered white patches and blotches. The lower shell margins are mostly white. The lower surface [= the base] is white and has numerous small teeth. This species is uncommon and is found offshore.
Umbilia hesitata (Iredale, 1916), abapertural and apertural views, length 10.2 cm, width 5.5 cm, Australia.
Acknowledgment: I want to thank Lindsey T. Groves, Collections Manager of Marine Mollusks at the Natural History Museum of Los Angeles County, California, for providing me with the latest information concerning the generic names of the cowries mentioned in this blog.
References Used:
Abbott, R.T. and S.P. Dance. 1992. Compendium of seashells. A full color guide to more than 4,200 of the world’s marine shells. E.P. Dutton, New York, 410 pp.
Groves, L.T. and R.L. Squires. 2023. Revison of northeast Pacific Paleogene cypraeoidan gastropods, including recognition of new species: implications for paleobiogeographic distribution and faunal turnover. PaleoBios 40(10):1-52. [pdf is free online]
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