Donkey Thorn Oyster Shell, Spondylus limbatus

Donkey Thorn Oyster Shell, Spondylus limbatus. Shell provided by the commercial fishermen of the greater Los Cabos area, March 2014. Size: 5.8 cm (2.3 inches) x 5.3 cm (2.1 inches).

The Donkey Thorn Oyster, Spondylus limbatus (G.B. Sowerby, II, 1847), is a bivalve mollusk that is a member of the Spondylidae Family of Spiny Oysters. They are also known as the Cat’s Tongue Oyster and in Mexico as almeja burra, callo escarlopa and ostra espoinosa burricais. The shell is solidly built and oval shaped. The external surface has radiating lines with short spines; in older individuals the spines may be worn down. The exterior of the shell is pinkish-red and the interior is white, with a purplish red border. The Donkey Thorn Oyster shell  reach a maximum of 25 cm (9.7 inches) in length and 21 cm (8.3 inches).

Donkey Thorn Oysters are found attached to solid substrate from the intertidal zone to depths up to 53 m (175 feet). They are found from San Alijo Rocks, Baja California Sur to Ecuador and in the Sea of Cortez from San Felipe, Baja California to Cabo San Lucas, Baja California Sur.

Synonyms include Spondylus calcifer, Spondylus coccineus, Spondylus lamarckii, Spondylus punicus, Spondylus radula, and Spondylus smithii.