Slippersnails have unique ability to change genders
The Atlantic slippersnail (Crepidula fornicata) is one of the most common shells found along the beaches of Lovers Key State Park. The shell is shaped like an egg or oval that has been cut in half, while the underside of the shell is a ledge – extending about half the length of the animal – to support its internal organs. The spotted slipper snail, spiny slippersnail and eastern white slipper snail can also be found along our coastline but are not as common as the Atlantic slippersnail. These intriguing shells are quite often picked up by beachcombers and then placed back on the beach. Beachcombers may not find them as enchanting as some of the other more “beautiful” shells but these little snails lead quite extraordinary lives.
One of the most intriguing facets about all seashells is that the animal (mollusk) makes the shell. All seashells found on the beach are the protective and supportive skeletons left behind after the animal has died or possibly been eaten by another mollusk or larger predator. The most common shells are from bivalves (two hinged shells such as clams) and gastropods, which are snails (typically with one coiled shell). Slippersnails as the name may give you a hint that they belong to the latter group. Many snails have a foot (body), which allows them to maneuver, but once slippersnails reach adulthood they typically anchor themselves to a hard substrate and remain stationary.
Slippersnails are colonial snails with one female and many males. If you find a live colony of slippersnails it is quite a sight to see as they live in stacks with the largest and oldest on the bottom and the snails progressively get smaller towards the top of the stack. The female is found on the bottom of the stack and the rest of the colony are males. So what happens when the female dies? The largest male turns into a female. The sex change is not precisely timed but depends on the presence of other individuals in the stack. What an amazing adaptation to ensure survival in the harsh beach environment for these little snails.