Species Description: Smaragdia viridis is a small nerite, ¼ to 1/3 inches long (Smith 1951, Abbot 1989), with a glossy, brilliant green shell (Rueda & Salas 2007; Abbot 1989; Smith 1951). It often has small white spots or bars incorporated into its shell patterns, and occasionally thin wavy black lines (Rueda & Salas 2007; Abbot 1989). Shell shape overall is rounded and smooth with a flattened spire. S. viridis has a wide shell aperture with a round to oval lip (Rueda & Salas 2007) and a cream-colored underside, with no operculum. Its radula has fewer fine cutting edges and stronger, finer, more numerous cuspid edges than many related nerites (Thiele 1992; Baker 1923), a possible adaptation for breaking through the tough cell walls of seagrasses (Rueda & Salas 2007). Its body is bright green (hence the common name “emerald nerite”) and flattened, with a broad, short head and long tentacles (Smith 1951).
Habitat & Regional Occurrence: Worldwide, Smaragdia viridis is found in Florida, the Caribbean, the Canary Islands, the Mediterranean Sea and tropical West Africa. This particular subspecies, Smaragdia viridis viridemaris, is found in Florida and Caribbean seagrass beds (Rueda & Salas 2007; Abbot 1989). There is not much information on its distribution within the IRL, but it could likely correspond to the distribution of T. testudinum (Rueda & Salas 2007).
Physical Tolerances: Although the temperature tolerance of S. viridis is unknown (Fraenkel, 1968), related species living in intertidal areas are known to tolerate a wide range of temperatures. S. viridis viridemaris is strictly marine (Thiele 1992).
Size, Lifespan & Reproduction: Little is known about the life history of this species (Rueda & Salas 2007). They form egg capsules which are reinforced with spherulites, small solid particles produced by the female (Andrews, 1937). Eggs hatch into planktotrophic veligers, remaining in the plankton for a relatively long period of time (Barroso & Matthews-Cascon, 2009). The larvae have smooth white shells that are small in comparison to the fully developed larval body. The velum is bilobed (Scheltema, 1971).
Trophic Mode: Although an herbivorous snail like most nerites, S. viridis is unusual in that it seems to feed directly on seagrasses, as opposed to feeding on epiphytes growing on the seagrass blades. (Rueda & Salas, 2007). S. viridis viridemaris is often closely associated with Thalassia testudinum (Rueda & Salas, 2007). It is sometimes found washed ashore with drifting material on protected beaches (Smith 1951).
Some related species such as Nerita versicolor and Nerita peloronta are preyed upon by octopus, birds and fish (Wodinsky 1969, Bovbjerg 1984). It is possible that the emerald nerite would have similar predators, though its small size may make it a less desirable prey item.
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Andrews, E. A. 1937. Spherulites as Specific Characters in Certain Gastropods. Transactions of the American Microscopical Society, 56: 237-242.
Baker, H. B. 1923. Notes on the Radula of the Neritidae. Proceedings of the Academy of Natural Sciences of Philadelphia 75: 117-178.
Barroso, C. X, and Matthews-Cascon, H. 2009. Spawning and intra-capsular development of Neritina zebra (Bruguière, 1792) (Mollusca: Gastropoda: Neritidae) under laboratory conditions. Invertebrate Reproduction and Development, 53: 137–143.
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Fraenkel, G. 1968. The Heat Resistance of Intertidal Snails at Bimini, Bahamas; Ocean Springs, Mississippi; and Woods Hole, Massachusetts. Physiological Zoology, 41: 1-13.
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Scheltema, Rudolf S. 1971. Larval Dispersal as a Means of Genetic Exchange between Gegraphically Separated Populations of Shallow-Water Benthic Marine Gastropods. Biological Bulletin, 140: 284-322.
Smith, Maxwell. 1951. East Coast Marine Shells, 4th Ed. Edwards Brothers Inc. Ann Arbor, Michigan
Thiele, Johannes. 1992. Handbook of Systematic Malacology. Translator: J.S. Bhatti. National Science Foundation, Smithsonian Institution Libraries, Washington DC.
Wodinsky, Jerome. 1969. Penetration of the Shell and Feeding on Gastropods by Octopus. Oxford University Press, American Zoologist, 9: 997-1010.