Noble Giant Turrid Shell, Polystira nobilis
Noble Giant Turrid Shell, Polystira nobilis. Shell provided by the commercial fishermen of the greater Los Cabos area, Baja California Sur, May 2014. Size: 5.7 cm (2.3 inches) x 2.0 cm (0.8 inches).
Phylogeny: The Noble Giant Turrid, Polystira nobilis (Hinds, 1843), is a gastropod mollusk that is a member of the Turridae Family of Turrid Shells. The genus Polystira is one of twenty-five genera in this family, and there are twenty-five species in this genus. They are known in Mexico as Pleurotoma Noble.
Description: Noble Giant Turrid shells are spindle-shaped and consist of eight concave whorls. They have a high spire, a long open siphonal canal, and a medium sized aperture. The shell is sculpted by raised spiral lines that follow the whorls. The exterior and interior of the shell are white with some specimens displaying brown blotching. The periostracum is brown. Noble Giant Turrid shells reach a maximum of 12.5 cm (4.9 inches) in length. Noble Giant Turrids are similar to the Picta Turrid, Polystira picta, but have a narrower body.
Habitat and Distribution: Noble Giant Turrids are found in muddy sand environments at depths between 30 m (100 feet) and 168 m (550 feet). They are a subtropical to tropical Eastern Pacific species that are found in all Mexican waters of the Pacific Ocean with the exception that they have not been documented along the west coast of the Baja. They ar found throughout the Sea of Cortez.
Ecology and Behavior: Noble Giant Turrids are a poorly studied and understood species. There is very limited documentation of their diet, predation, reproduction or ecosystem interactions. Other species in Family Turridae are predators that feed primarily on polychaetes. They are gonochoric and reproduce sexually, with internal fertilization. The eggs are laid in protective capsules. 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.
Synonyms: Pleurotoma nobilis.