Giant Forreria Shell, Forreria belcheri

Giant Forreria Shell, Forreria belcheri. Shell collected off the beach of Bahía Concepción, Baja California Sur, October 2019. Size: 16.8 cm (6.6 inches) x 9.3 cm (3.7 inches). Collection, photograph and identification courtesy of Bob Hillis, Ivins, Utah.

Phylogeny: The Giant Forreria Shell, Forreria belcheri (Hinds, 1843), is a gastropod mollusk that is a member of the Muricidae Family of Rock Shell Shells.  The genus Forreria is one of one hundred ninety-eight genera in the Rock Shell Family, and there are two species in this genus. This species is also known as Belcher’s Chorus Shell, the Giant Chorus Shell, and Belcher’s Murex.

Description: Giant Forreria Shells are large and heavy with five to seven large spined whorls, a relatively low to moderate spire, a curved, long, open siphon canal with older siphon canals being immediately adjacent the current canal, and an aperture that is large with a thin outer lip that has one large tooth at its lower end. The exterior of the shell is cream to tan in color, with darker and lighter banding; the interior is white. The Giant Forreria Shells reach a maximum of 10.4 cm (7.4 inches) in length and 5.8 cm (2.3 inches) in height.

Habitat and Distribution: Giant Forreria Shells are found on shallow mudflats and on soft substrates. They live in the intertidal zone and to depths up to 35 m (115 feet). They are a temperate to subtropical Eastern Pacific species that in Mexican waters have a limited range being found along the west coast of the Baja Peninsula, from the northern border south to Guerrero Negro, Baja California. They have not been documented from the Gulf of California, but are  very similar in appearance to the Cortez Forreria Shell, Forreria corteziana.

Ecology and Behavior: Giant Forreria Shells are predators that feed primarily on bivalves. They are gonochoric and reproduce sexually, with internal fertilization. There is no mention in the available literature of them engaging in any types of parasitic, commensal, 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.

Synonym:  Murex belcheri.