Chubby Simnia, Simnia avena

Chubby Simnia, Simnia avena. Underwater photographs taken in Zihuatanejo Bay, Guerrero, November 2019. Photographs courtesy of Ron Woheau, Zihuatanejo.

Phylogeny: The Chubby Simnia, Simnia avena (Sowerby, 1833), is a member of the Ovulidae Family of False Cowry Shells.

Morphology:  The shells of the Chubby Simnia are shorter and stouter than most Simnias, but it is still an elongated, narrow, thin, spindle-shaped shell. The exterior of the shell may be smooth or marked with very fine, spiral lines, sometimes thin enough that it appears translucent. The aperture is very long and it grows wider at its lower end. The shells vary in color and can be brownish-lavender, lavender, orange, rose or white. The canal ends are usually a darker yellow or orange. Chubby Simnia shells reach a maximum of  2.4 cm (0.9 inches) in length.

Habitat and Distribution:  Chubby Simnias are found on gorgonians at depths between 5 m (15 feet) and 76 m (250 feet). They range from Central California to Peru, including the Cocos and Galapagos Islands. They are found throughout the Sea of Cortez.

Diet:  The Simnia avena snails feed on the polyps and flesh of their gorgonian host, including species including Eugorgia, Muricea and Psammogorgia.

Synonyms: Delonovolva aequalis, Neosimnia avena, Neosimnia capitia, Neosimnia formicaria, Ovula aequale, Ovula avena, Ovula hordacea, Ovula lividum, Ovula simile, Simnia aequalis, and Simnia rufa.

Note:  The Chubby Simnia Shell is presented within a sister domain, Mexican-shells.org under Mexican-shells.org/chubby-simnia.

Request for Help:  With minimal documentation of this species and ambiguity in the Ovulidae family, there is some confusion on the correct common name.  We would welcome any input on this topic.