Broderip’s Thistle Trophon Shell, Acanthotrophon carduus
Broderip’s Thistle Trophon Shell, Acanthotrophon carduus. Size: 2.0 cm (0.8 inches) x 1.1 cm (0.4 inches). Shell courtesy of the commercial fishermen of the greater Los Cabos area, Baja California Sur, March 2018.
Phylogeny: Broderip’s Thistle Trophon, Acanthotrophon carduus (Broderip, 1833), is a gastropod mollusk that is a member of the Muricidae Family of Rock Shells. The genus Acanthotrophon is one of one hundred ninety-eight genera in this family, and there are five species in this genus.
Description: Broderip’s Thistle Trophon Shell consists of seven whorls with a diamond shaped profile. Sculpting consists of nodes and spines along the tops of the whorls; more worn shells will have only spines near the aperture. The spire length is very similar to the body whorl length. The aperture is oval in shape and the inside of the outer lip is marked by a series of ridges. The siphon canal is about as long as the aperture, and is open. The exterior of the shell is scaly in texture and white in color. Some specimens have brown blotches or or brown node tips. The interior is white. Broderip’s Thistle Triton Shells reach a maximum of 2.8 cm (1.1 inches) in length and 1.5 cm (0.6 inches) in height.
Habitat and Distribution: Broderip’s Thistle Trophons are found attached to rocks and are found at depths between 12 m (40 feet) and 100 m (330 feet). They are a tropical Eastern Pacific species that are found in all Mexican waters of the Pacific Ocean with the exception that they are absent from the west coast of the Baja Peninsula and from north of Mulegé, Baja California Sur, in the Sea of Cortez.
Ecology and Behavior: Broderip’s Thistle Trophons are predators that feed primarily on shelled 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 Broderip’s Thistle Trophons has not been formally evaluated. However, they are fairly common with a relatively wide distribution and should be considered to be of Least Concern.
Synonyms: Murex carduus