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Texas Invasive Species Institute

Texas Invasive Species Institute

Giant Ramshorn Snail

Marisa cornuarietis

Class: Gastropoda
Order: Architaenioglossa
Family: Ampullariidae

Marisa cornuarietis

Photographer: Amy Benson Affiliation:U.S. Geological Survey Source:www.bugwood.org Copyright: CC BY 3.0


The Goldenhorned Marissa (Marissa cornuarietis) 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.


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.


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.

Native Origin

Northern South America and the Caribbean

Current Location

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.


U.S. Present: AL, AZ, CA, FL, GA, TX

Texas: San Antonio, San Marcos River, and Comal River


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).


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.


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.

Rawlings, Timothy A., Kenneth A. Hayes, Robert H. Cowie, and Timothy M. Collins. 2007. The identity, distribution, and impacts of non-native apple snails in the continental United States. BMC Evolutionary Biology 7:97.

Schulte-Oehlmann, U., C. Bettin, P. Fioroni, J. Oehlmann, and E. Stroben. 1995. Marisa cornuarietis (Gastropoda, prosobranchia): a potential TBT bioindicator for freshwater environments. Ecotoxicology 4(6): 372-384. United States Geological Survey. 2012. 

Seaman, D. E., and W. A. Porterfield. 1964. Control of Aquatic Weeds by the Snail Marisa cornuarietis. Weeds 12(2): 87-92. 

USGS Nonindigenous Aquatic Species Database, Gainesville, FL.

 Internet Sources:


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