Sanguine Cantharus Shell, Gemophos sanguinolentus

Sanguine Cantharus Shell, Gemophos sanguinolentus. Shell courtesy of the commercial fishermen of the greater Los Cabos area, Baja California Sur, May 2010. Size: 2.3 cm (0.9 inches) x 1.8 cm (0.7 inches).

Phylogeny: The Sanguine Cantharus Shell, Gemophos sanguinolentus (Duclos, 1833), is a gastropod mollusk that is a member of the Pisaniidae Family of False Triton Shells. The genus Gemophos is one of twenty genera in this family, and there are eleven species in this genus. They are also known as the Measles-mouth Whelk Shell and in Mexico as Cantarus Sanguinolento.

Description: Sanguine Cantharus Shells are stocky and solid, and consist of five or six whorls. They have a large body whorl large, a moderately large spire, and a large oval aperture. There are canals at the top and bottom of the aperture. Their outer lip is thick and crenulated (marked with numerous small ridges). The inner lip is red with raised white bumps. They are sculpted with several  wide, rounded, axial ribs and fine spiral ridges. The exterior of the shell is gray to brown in color, with broken brown spiral lines; the interior is white. The Sanguine Cantharus Shells reach a maximum of 3.2 cm (1.3 inches) in length and 2.5 cm (1.0 inch) in height.

Habitat and Distribution: Sanguine Cantharus are found on rock and coral in the  intertidal zone, and to depths up to 20 m (65 feet). They are a subtropical to tropical Eastern Pacific species that are found in all Mexican waters of the Pacific Ocean, including the Tres Marias Islands, with the exception that they are absent from north of Todos Santos, Baja California Sur, along the central and northwest coasts of the Baja Peninsula, and north of Guaymas, Sonora, in the Sea of Cortez.

Ecology and Behavior: Sanguine Cantharus are a poorly studied and understood species. There is very limited documentation of their diet, predation, reproduction or ecosystem interactions. Other species in the Pisaniidae Family are predators that feed primarily on mollusks, barnacles, and worms. They are gonochoric and reproduce sexually, with internal fertilization. Their engagement in any type of commensal, parasitic, or symbiotic relationship has not been formally documented. From a conservation perspective the Sanguine Cantharus has not been formally evaluated. However, they are fairly common with a relatively wide distribution and should be considered to be of Least Concern.

Synonyms: Cantharus sanguinolentus, Pollia Haemastoma, and Purpura anguinolenta.