Less Charismatic Predators
Crayfish
There were early reports of crayfish (Procambarus sp.) eating apple snails (Snyder and Snyder 1971). Darby et al. (2009) studied the consumption rates and size limitations of snails in the lab by Procambarus alleni. They found that the maximum size of snails eaten by crayfish increased with crayfish size, or carapace length. Crayfish 17-35.5 mm in size (carapace length) ate snails 4-11 mm in size. Crayfish were observed eating snails by crushing snail shells with their chelipeds (large claws) and/or using their chelipeds to hold the snail and their maxillipeds (second set of walking legs) to remove the operculum and extract the soft body parts.
Turtles
Among the small turtles (see Predator perspectives for large turtles), Sternotherus minor (the loggerhead musk turtle, which occurs in Florida) has been reported to eat apple snails in the lab (Snyder and Snyder (1971). These authors also reported that apple snails responded behaviourally in the lab to odors of other turtle species, including Kinosternon bauri and Sternotherus odoratus. Darby et al. (2009) studied the consumption of snails in the lab by two of these turtle species, the mud turtle (Kinosternon bauri), which occurs throughout the Florida peninsula, and the musk turtle (Sternotherus odoratus), which occurs throughout Florida. Turtles 37-91 mm in size (carapace length) ate snails 9-22 mm in size. Both species of turtle readily consumed small snails (up to 10 mm). Larger snails (>15 mm) were also consumed, but turtles were observed positioning snails in aquaria corners to more easily handle them.
Fish
Darby et al. (2009) also studied the consumption of snails in the lab by two species of fish, the redear sunfish (Lepomis microlophus) and the Mayan cichlid (Cichlosoma urophthalmus). As noted under Predator Perspectives, the redear sunfish was known to take apple snails as prey (Chable 1947). The Mayan cichlid, known to eat other types of snails, is a non-native species from Central America that was first recorded in Florida in 1983 (Bergmann and Motta 2005). Redear sunfish 9-29.5 cm in size (length) ate snails 5-19 mm in size. Mayan cichlids of comparable size ate larger snails (based on a small sample size). Both fish species ate snails in a similar manner; the fish manipulated snails by positioning them in their buccal cavity (mouth) and then crushed them with their pharyngeal jaws. Small snails were easily consumed, but snails >13 mm were spat out and repositioned before being crushed and consumed (with some left uneaten).
Literature Cited
- Bergmann, G.T. and P.J. Motta. 2005. Diet and morphology through ontogeny of the nonindigenous Mayan cichlid ‘Cichlasoma (Nandopsis)’ urophthalmus (Günther 1862) in southern Florida. Environmental Biology of Fishes 72:205-211.
- Chable, A.C. 1947. A study of the food habits and ecological relationships of the sunfishes of Northern Florida. M.S. Thesis, the University of Florida, Gainesville, Florida.
- Darby, P.C., N.H. Glass, D.J. Mellow, S.E. Kell, R.E. Eckert, and P.L. Valentine-Darby. 2009. Apple snail demography in the Everglades: 2005-2007. Final Report to U.S. Fish and Wildlife Service, Vero Beach, FL.
- Snyder, N.F.R. and H.A. Snyder. 1971. Defenses of the Florida apple snail (Pomacea paludosa). Behavior 40:175-215.