Slender Triton Shell, Monoplex macrodon

Slender Triton Shell,  Monoplex macrodon. Shell collected off the beach in the greater Los Cabos area, Baja California Sur, March 2016. Size: 4.6 cm (1.8 inches) x 2.5 cm (1.0 inch).

Slender Triton,  Monoplex macrodon.  Shell collected off the beach in the greater Agua Verde area, Baja California Sur, March 2020. Size: 6.9 cm (2.7 inches) x 3.7 cm (1.5 inches). Collection, photograph and identification courtesy of Barry Mastro, Escondido, California.

The Slender Triton, Monoplex macrodon (Valenciennes, 1832), is a gastropod mollusk that is a member of the Cymatiidae Family of Tritons. They are also known as the Hairy Triton. The shells are robust with six or seven whorls each with a strong varix, numerous fine, spiral lines, a long spire that is equal in length or longer than the aperture which is a is elongated with raised white lines marking the inner and outer lips. The exterior of the shell is dark brown, light brown, orange-brown, reddish brown, or yellowish-brown in color with white spiral banding; the interior is usually rust or reddish-brown. Live specimens are covered with a “hairy” brown periostracum. Slender Triton Shells reach a maximum of 9.0 cm (3.5 inches) in length and 4.8 cm (1.9 inches) in height.

The Slender Tritons are found attached to rocks and within coral and rubble from the intertidal zone to depths up to 255 feet. They range from Cedros Island, Baja California to Columbia, including Clipperton, Cocos and Galapagos Islands and they are found throughout the Sea of Cortez. This species has historically been often confused with other global “Hairy Tritons” and thus range and depth records for this species may be inaccurate because of confusion regarding species.

Synonyms include Cymatium pilearis macrodon, Monoplex pilearis, and Tritonium macrodon.