The American Tusk Shell
Tusk shells belong in the molluscan class Scaphopoda, and are so named because they resemble small elephant tusks. The American Tusk Shell, Paradentalium americanum (Chenu, 1843), is the most common among several local members of the tusk-shell family Dentaliidae. Its shell reaches about an inch in length, and has a sculpture of six evenly spaced longitudinal ridges, with a seventh ridge found in some specimens. The sculpture pattern imparts a hexagonal outline to cross-sections of the shell (see figure). The local tusk shells have been studied by Bailey-Matthews National Shell Museum's own Marine Biologist Rebecca Mensch.
The American Tusk Shell, Paradentalium americanum, from Sanibel. A juvenile shell is represented in the central image. Photo by José H. Leal.