Stearns’ Turrid Shell, Megasurcula stearnsiana
Stearn’s Turrid Shell, Megasurcula stearnsiana. Shell collected offshore San Diego, California, July 2000. Size: 4.4 cm (1.7 inches) x 1.7 cm (0.7 inches). Collection, identification and photo courtesy of Bob Hillis, Ivins, Utah.
Phylogeny: Stearns’ Turrid, Megasurcula stearnsiana (Raymond, 1904), is a gastropod mollusk that is a member of the Pseudomelatomidae Family of Turrid Shells. The Megasurcula Genus is one of fifty-four genera in this family, and there are only two species in this genus. The genus name Megasurcula comes from Greek and Latin roots and means “large siphon.” This species was named in honor of Robert E. C. Stearns who was a naturalist, paleontologist, and malacologist. He was the Assistant Curator of the Department of Mollusks at the Smithsonian Institution in the late 19th century. He made significant contributions to the field of malacology as relates to California and Florida. In Mexico these shells are known as Túrido de Stearns.
Description: Stearns’ Turrid Shells are small to medium-sized and fusiform (spindle-shaped). They consist of 7-9 whorls. The body whorl is large and the spire is moderately high. The upper whorls are flat-sided. The suture (where the body whorl joins the spire) is concave. These shells are sculpted with axial growth lines and spiral threads. The aperture is elongate, taking up more than half the shell length. The outer lip is thin and smooth. The columella is smooth and curved. The siphonal notch and posterior notch are prominent. These shells are cream, tan, or orangish in color. They have a wide, dark brown, band below the suture, and about ten narrower spiral lines on the body whorl. The interior is yellow. Stearns’ Turrid Shells reach 6.0 cm (2.3 inches) in length. Stearns’ Turrid Shells are similar in appearance to Cooper’s Nutmeg Shell, Cancellaria cooperii (larger, heavier, with axial ribs, and an obvious knobs) and Carpenter’s Turrid Shell, Megasurcula carpenteriana (larger, more angular, with finer brown lines).
Habitat and Distribution: Stearns’ Turrids are found on sandy substrates, at depths between 15 m (50 feet ) and, at least, 120 m (394 feet). These shells are a temperate to subtropical Eastern Pacific species. They have a very limited range in Mexican waters being found from Todos Santos Bay, Baja California northward along the central and northwest coasts of the Baja Peninsula..
Ecology and Behavior: Turrid Shells, like Cone Shells, are venomous predators that utilize their uniquely designed radula as a harpoon to capture and then envenomate their prey. The venom paralyzes the prey animal. The diet of Stearns’ Turrid Shells is poorly understood, beyond “various small invertebrates”. They are gonochoric and reproduce sexually. 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 considered to be of Least Concern.
Synonyms: Conus stearnsianus and Pleurotoma (Genota) stearnsiana.