Apple snail; the scientific name is Pomacea and is larger than most freshwater snails. They can be separated from other freshwater species by their oval shell, which has the umbilicus of the shell perforated or broadly open. The umbilicus is the axially aligned, hollow, cone-shaped space within the whorls of the coiled mollusk shell. Florida has four species, only one is native and considered beneficial. The other three were introduced. All are tropical/subtropical and are not known to withstand water temperatures below fifty degrees Fahrenheit.
Apple snails (Pomacea paludosa) can be found throughout the Florida peninsula and believed to have existed since the Pliocene. It is also native to Cuba and Hispaniola, but collections have also been found in Alabama, Georgia, Hawaii Louisiana, Oklahoma and South Carolina. It is considered beneficial as it’s the primary food for the Everglades kite and Ridgway. The apple snail cannot survive in northern Florida waters unless the water is artificially headed by industrial wastewater or in warm springs. They occur as far west as the Choctawhatchee River.
One of the most common apple snails to be introduced is the island apple snail (Pomacea maculate). It was released in South Florida in the early 1980s by people in the tropical pet industry and rapidly expanded throughout the state. It can now be found in Alabama, Georgia, Hawaii, Louisiana, North Carolina, South Carolina and Texas. There have also been introductions in Arizona, California, and Hawaii. The island apple snail is a potential threat to Florida’s aquatic ecosystem.
Originally from Brazil, the spike-topped apple snail (Pomacea diffusa) was introduced into southern Florida in the 1950s. Unlike the Florida apple snail, it has a lower tolerance for cold water and is established in Broward, Miami-Dade, Monroe and Palm Beach counties. Collections have been seen in parts of central and north-central Florida, Alabama, and Mississippi. Marketed for aquariums under the name of “golden apple snail.” There have been commercial varieties bred for the aquarium which includes the “albino mystery snail.” Often, they are dumped into isolated bodies of water and have been found as far north as Alachua County, Florida. Their diet consists of decaying vegetation.
Diets between the island apple snail and the native Florida apple snail are worlds apart. The island apple snail primarily eats rooted aquatic vegetation. For the Florida apple snail, the diet consists of periphyton, a complex mixture of algae, cyanobacteria, heterotrophic microbes and detritus attached to submerged surfaces in most aquatic ecosystems.
Chemical means of elimination of the apple snail has been attempted, but with no effect. Currently, the most effective methods are hand or mechanical removal of snails and egg masses. They do have some natural predators in Florida including, limpkin, Everglades (snail) kits, raccoons, turtles, and alligators. It is believed that certain ducks and redear sunfish will consume smaller immature snails. If you scrape the egg masses off, make sure it’s only the pink egg masses and you can allow them to fall into the water since inundated eggs will not hatch. The large white egg masses are laid by the native Florida apple snail and should be left alone. Never release apple snails from aquaria into the water. Permits are required for importation or interstate shipment of all marine and freshwater snails.