Shell of the Week: The Dog-head Triton

Ranularia cynocephala (Lamarck, 1816) has a sturdy shell that reaches 70 mm (about 2.8 inches). The shell has squarish whorls, a long siphonal canal that may be recurved, and may bear a varix, which denotes the occurrence of a growth stop). The shell sculpture consists of strong spiral cords crossed by weaker axial ribs. The outer lip of the shell aperture is garnished internally with 7 strong, white teeth. The shell color is usually golden-brown, often with a whitish spiral band near the middle of whorl. This is a very uncommon species locally and, as with most tritons, occasional findings may indicate isolated, independent arrivals of long-lasting planktonic larvae on our shores in contrast to the presence of permanent local populations. Read more about mollusks and their shells in our Shell Guide.

The Dog-head Triton, Ranularia cynocephala, from Sanibel. Photos by José H. Leal.

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