
A Benign Behemoth: The Giant Keyhole Limpet
Reaching about 125 mm (about 5 inches), the Giant Keyhole Limpet, Megathura crenulata G.B. Sowerby I, 1825, is one of the behemoths of the limpet universe. A herbivore gastropod, this unusual mollusk stands out not only because of its size, but also because its mantle can extend out, completely enveloping the shell. The Giant Keyhole Limpet’s blood molecule hemocyanin (a molecule that carries oxygen pretty much like hemoglobin does in vertebrates) has the potential for use as a vaccine-carrier