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 Forrerias 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 are found in Mexican waters of the Pacific Ocean being limited to coastal waters of Guerrero Negro, Baja California, and northward along the central and northwest coasts of the Baja Peninsula. They are  very similar in appearance to the Cortez Forreria Shell, Forreria corteziana, found in the Sea of Cortez.

Ecology and Behavior:  Giant Forrerias are predators that feed primarily on bivalves. 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 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.