Calliostoma fragum (Philippi, 1848)

Calliostoma fragum has what might be considered an unusual diet. It is a fire eater. Well, sort of. Here in the Marshalls it appears to eat exclusively fire coral of the genus Millepora. We first noticed that this species was not especially rare, but could be found living only at night and only on colonies of live Millepora on the upper seaward slope. At first this seemed a surprise, but there are various reports in the literature of other Calliostoma species eating hydroids, which are non-calcified relatives of fire coral. A Millepora colony often covers several square meters and can support up to ten or so of various sizes of these small predators, although most colonies of the coral are free of the little parasites. The shells seem to max out at about 9mm tall. The first couple of images show it on its prey coral. Some of the other photos were shot on different backgrounds for contrast.

Three specimens, one tiny, are visible on fire coral in the photo below.

Very attractive animal.

Created 16 May 2011

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