Norris' top snail ( Norrisia norrisi ) is an extremely common snail found inhabiting kelp forests from Point Conception, California, south to the shores of Baja California, Mexico. Despite its commonality, it stands out as one of the most recognizable marine snails found in kelp forests. And it shouldn't come as a surprise to find out that it prefers to feed on giant kelp (Macrocystis pyrifera ) and other large species of brown algae.
While the shell is rough, and arguably not as pretty as the shells of other snails, the colors and striations create an interesting design that gives it real character. Sort of a working-person's snail, not some snail that is inherently pretty simply because of its shiny shell.
The snail's foot, upon which it crawls, is bright reddish orange and almost impossible to miss as you swim through a kelp forest. Even though the foot may not be greatly exposed, even a small bit of it is sufficiently eye catching.
Over the course of a day, these snails exhibit an interesting migration pattern. Starting in the surface canopy of the kelp forest, the snails migrate toward the bottom at dawn, turning back toward the surface at dusk. This vertical migration seems to be repeated on a daily basis.
This subject of this week's photo was on a kelp blade in a forest at San Clemente Island, the southern-most of California's Channel Islands. The photograph was made with a Canon EOS 10D dSLR and an EF 100 mm macro lens. Exposure was for 1/60 sec at f/11 with an ISO of 100. The camera and lens were housed in an Ikelite housing and lighting provided by twin Ikelite DS-125 strobes set to ETTL.