Common Names: Stomatella
Scientific Name: Stomatella varia
Stomatella look like a cross between a slug and a snail. Their shell is fairly flat and inconspicuous compared to the shells of most snails. They are typically mottled brownish green in color, but can also be black, gray or other colors which is where their species name of varia comes from. They stay under about 3/4″ in length.
Due the shell shape, the body is always exposed to some degree and the Stomatella use the techniques of being mostly nocturnal as well as being fast (at least for a snail) to avoid predators. When they are out during the day, they tend to be very secretive. They also can break off the rear portion of their foot to distract an attacker while they make their getaway.
Since Stomatella are mostly nocturnal a look at the tank walls after dark with a flashlight will usually spot these critters if they are present in the tank.
Good or Bad?
Stomatella are great additions to the reef tank. They are herbivores and feed upon micro algae in the reef tank much like any snail that you might go out to buy to do the same job and have the added benefit that they don’t move stuff around like regular snails can with their large shells and are more discrete if you don’t like a tank with a bunch of snails hanging on the glass.
Stomatella will reproduce in the reef tank, but don’t seem to reach nuisance population levels. Breeding has been observed during the daytime with all individuals climbing up to high points on the live rock and simultaneously releasing their eggs and sperm into the water. This can cause the tank water to look milky for a short time, but is nothing to worry about and will clear on its own. The filter feeders get to eat well when this occurs.
Unfortunately since they don’t have great shell protection, predatory animals in the tank such as hermit crabs, predatory shrimp and perhaps some fish can make a meal of them.
All pictures by ReefCorner and all rights reserved.