Many local species of marine gastropods lay their eggs in protective egg capsules, also known as egg cases. This is just what a female Mauve-mouth Drill, Calotrophon ostrearum (Conrad, 1846) will do. (The species was first covered in this column on April 22, 2016). Their eggs are laid in "crescent-shaped" capsules about 3/16 inch tall, usually on top of the egg cases of larger gastropods. The illustration shows, in addition to views of a shell of the species. two small clusters of egg cases (arrows) laid on a horse conch egg case. The top cluster shows embryos enveloped in red; the ones in the bottom cluster lack that color. The pigment may be or may be not related to murexine, a substance present in the egg capsules of other members of the family Muricidae.
The Mauve-mouth Drill, Calotrophon ostrearum, from Sanibel, and its egg cases (arrows) laid on a horse conch egg case. Photo by José H. Leal.