Texas Invasive Species InstituteMarisa cornuarietus
Giant Ramshorn Snail
Synonym(s):
Class: Gastropoda
Order: Architaenioglossa
Family: Ampullariidae
Photographer: Stijn A. I. Ghesquiere
Source: http://applesnail.net/content/species/marisa_cornuarietis.htm
Description
The Goldenhorned Marissa (Marissa cornuarietus) is a relatively large snail with 3.5-4 whirls in adults, 18-22 mm wide, and 48-56 mm high. The adult snails are flatter in appearance with the whirls stacking directly on top of the body, while juvenile snails are more globular in shape. The Goldenhorned Marissa is yellow to brown in color with darker (often black) stripes. However, a mutation exists where the snail lacks any stripes and is completely yellow in color.
Ecological Threat: Considered an aggressive scavenger, the Goldenhorned Marissa will consume nearly any and all vegetation in sight. First introduced as an aquarium pet, the snail has been reported to significantly damage aquarium habitats. The ability to reproduce rapidly combined with destructive behavior related to feeding, the Goldenhorned Marissa is capable of severely damaging agricultural areas and natural habitats found in ponds and streams by disrupting the current eco-region.
Biology: Eggs are laid in large gelatinous masses-containing 100-200 eggs on the surface of vegetation. The eggs swell up to 4 mm after 10 days and become transparent enough to see the snail moving. With a short hatching time, Goldenhorned Marissas are able to reproduce rapidly and become established in new areas.
History: The Goldenhorned Marissa was first introduced to the continental United States in south Florida in 1957. This population is believed to have become established through the pet trade by accidental escape or intentional release. The snail was later recorded in Texas in the early 1990's.
Habitat: First introduced in the United States as a way to clean aquariums, the Goldenhorned Marissa is known to prefer shallow bodies of water containing a large amount of vegetation. This snail can be found in streams, ponds, irrigation systems, and swamps. With a high tolerance to salinity at 30% concentration this snail is hearty, but not known to reproduce in high saline conditions.
Distribution
Native Origin: Northern South America and the Caribbean
U.S. Present: AL, AZ, CA, FL, GA, TX
Texas: San Antonio, San Marcos River, and Comal River
Resembles/Alternatives
Applesnails from the family Ampullariidae are difficult to differentiate between species due to similar appearances. Ampullariidae are characterized by the deep suture in the middle whirl of the shell. This feature distinguishes applesnails from other snails, but creates difficulties in identifying species within this family. Some specific species that are similar in appearance to the Goldhorned Marissa are the channeled applesnail (Pomacea canaliculata), island applesnail (Pomacea insularum), and titan applesnail (Pomacea haustrum).
Management
The only current management methods at this time are preventative. It is important to clean and drain boats or any water gear before leaving the site. As a relatively large snail, it is easy to notice and remove before leaving the area. If this snail is acquired as a pet, do not release it into the wild if it is no longer desired. As a hermaphroditic species, only one snail can establish a population and damage natural habitats.
References
Oliver-Gonzalez, Jose, Preston M. Bauman, and A. S. Benenson. 1956. Effect of the Snail Marisa Cornuarietis on Australorbis Glabratus in Natural Bodies of Water in Puerto Rico. The American Journal of Tropical Medicine and Hygiene 5: 290-296.
USGS Nonindigenous Aquatic Species Database, Gainesville, FL.
Internet Sources:
www.itis.gov
http://www.applesnail.net
