Gourd Rock Shell, Vasula melones

Gourd Rock Shell, Vasula melones. Shell collected off the beach within the greater Los Cabos area, Baja California Sur, August 2019. Size: 3.8 cm (1.5 inches) x 2.9 cm (1.1 inches).

Phylogeny: The Gourd Rock Shell, Vasula melones (Duclos, 1832), is a gastropod mollusk that is a member of the Muricidae Family of Rock Shell  Shells. The genus Vasula is one of one hundred ninety-eight genera in this family, and there are three species in this genus. They are also known as the Apple Rock Shell and in Mexico as Muricido Manzana and Púrpura Melón.

Description:  Gourd Rock Shells are globose, heavy, and thick in structure. They consist of five whorls and have a large body whorl. The spire is small and pointed. The shell’s exterior is sculpted with fine, spiral, grooves. The aperture is large and the outside lip of the aperture may show dentition (teeth). The exterior of the shell is black in color with white blotches. The interior is white, with yellow blotches. Some individuals show lavender to brown on the inside lip. Gourd Rock Shells reach a maximum of 6.0 cm (2.4 inches) in length and 4.6 cm (1.8 inches) in height.

Habitat and Distribution:  Gourd Rock Shells are found attached to rocks in the intertidal zone. They are a tropical Eastern Pacific species that  are found in Mexican waters of the Pacific Ocean from Cabo Pulmo, Baja California Sur south to Guatemala.

Ecology and Behavior: Gourd Rock Shells are a poorly studied and understood species. There is very limited documentation of their diet, predation, reproduction or ecosystem interactions. Other species in the Muricidae Family prey primarily on barnacles and mollusks. They are gonochoric and reproduce sexually. There is no mention in the available literature of them engaging in any types of commensal, parasitic or symbiotic relationships. From a conservation perspective they have not been formally evaluated however they are fairly common with a relatively wide distribution and should be consider to be of Least Concern.

Synonyms:  Purpura crassa, Purpura melones, Thais (Vasula) melones and Thais melones.