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The Nonindigenous Occurrences section of the NAS species profiles has a new structure. The section is now dynamically updated from the NAS database to ensure that it contains the most current and accurate information. Occurrences are summarized in Table 1, alphabetically by state, with years of earliest and most recent observations, and the tally and names of drainages where the species was observed. The table contains hyperlinks to collections tables of specimens based on the states, years, and drainages selected. References to specimens that were not obtained through sighting reports and personal communications are found through the hyperlink in the Table 1 caption or through the individual specimens linked in the collections tables.

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Common name: titan applesnail

Synonyms and Other Names: Ampullaria haustrum

Taxonomy: available through www.itis.gov

Identification: Pomacea haustrum is a large aquatic snail with globose shells that can vary from a dark green to brown in color, with brown striping throughout and lighter color closer to the shell opening or aperture (Ghesquiere 2007). Similar to P. maculata and P. canaliculata, they have a sutural channel between the body whorl of the shell that is easily distinguishable (Rawlings et al. 2007). Pomacea haustrum have a large aperture and a thick operculum, a door-like appendage that covers the aperture of the shell, allowing the snail to seal closed. Body color of P. haustrum can vary from a gray to brown, having darker pigmentation in the siphon and tentacles. Their siphon is long when extended and kept retracted beneath the shell when at rest (Ghesquiere 2007). Populations in Florida have been found with individuals that have both tall and short spired shells (Howells et al. 2006).

Pomacea haustrum can be easily confused with other large Pomacea species such as the giant applesnail (P. maculata). Pomacea haustrum has a larger aperture than that of P. canaliculata or P. maculata (Cazzaniga 2002). When comparing shell shape between P. haustrum and P. canaliculata, P. haustrum will have a shell that is less round and is relatively higher (Ghesquiere 2007). Unlike other Pomacea species within the United States, both invasive and native, P. haustrum lay green egg masses in an irregular honeycomb shape, very dissimilar to the pink and white egg masses of the other introduced and native Pomacea species in the U.S. Individual eggs are approximately 3-5 mm in size (Rawlings et al. 2007).

Size: Shell 9-12 cm in height

Native Range: South America: Brazil, Peru, and Bolivia (Rawlings et al. 2007)

Alaska	Hawaii	Puerto Rico & Virgin Islands	Guam Saipan

Hydrologic Unit Codes (HUCs) Explained
Interactive maps: Point Distribution Maps

Ecology: Pomacea haustrum prefer shallow, slow-moving to stagnant water such as lowland swamps, ponds and canals with muddy bottoms (Cowie 2002). They are known to tolerate low levels of salinity and oxygen in the water. However, mortality increases and performance decreases with increased salinity parameters. (Rodrigues et al. 2025). As they are a tropical species, P. haustrum is unable to survive low temperatures. This species has a high tolerance to variations in pH and is resistant to desiccation, capable of surviving in humid environments for up to a year as adults and up to 49 days as hatchlings (Rodrigues et al. 2025). Pomacea haustrum is omnivorous and have been reported to have a higher propensity to eat macrophytes than algae (Morrison and Hay 2011). While mainly an aquatic species, P. haustrum will spend time in terrestrial habitat. They are most active at night.

It takes approximately one year for P. haustrum to reach sexual maturity. This species prefers to copulate in the morning and oviposit at night (Guimarães 1981). Females lay their green egg masses in aquatic habitats out of the water just above the waterline (Rawlings et al. 2007). The average clutch size is 236 eggs. Each egg is 3-5 mm in length and take 9-30 days to hatch (Guimarães 1981; Rawlings et al. 2007).

Means of Introduction: Pomacea haustrum were likely introduced from intentional releases and escapes from the aquarium and pet trade (Howells et al. 2006).

Status: Established in Palm Beach County, FL. (Rawlings et al. 2007)

Impact of Introduction: Pomacea haustrum can consume 70-15 mg of aquatic plant material per gram of body weight each day (Morrison and Hay 2011). As an ampullariid, P. haustrum are potential intermediate hosts of rat lungworm, Angiostrongylus cantonensis (Howell et al. 2006).

Remarks: Invasive populations of P. haustrum in Palm Beach County were originally thought to be P. canaliculata until genetic analyses revealed they were not. For this reason, specimens collected in the 1970’s from the area around Loxahatchee National Wildlife Refuge that are identified as P. canaliculata are likely P. haustrum (Howells et al. 2006).

The U.S. Fish and Wildlife Service’s ecological risk screening summary for the titan applesnail categorized the risk of this species as uncertain due to limited dispersal since arrival in the 1970’s, and little information is available on the potential impacts of this species (USFWS 2018).

References: (click for full references)

Cazzaniga, N.J. 2002. Old species and new concepts in the taxonomy of Pomacea (Gastropoda: Ampullariidae). Biocell 26:71-81.

Cowie, R.H. 2002. Apple snails (Ampullariidae) as agricultural pests: their biology, impacts and management. Pages 145-192 in Barker, G.M, ed. Molluscs as Crop Pests. CABI Publishing. Wallingford, UK.

Ghesquiere, S. 2007. Apple snails (Ampullariidae). Available: http://applesnail.net/. Accessed on March 27 2025.

Guimarães, C.T. 1981. Some laboratory observations on the biology and ecology of Pomacea haustrum (Reeve, 1856). Memorias Do Instituto Oswaldo Cruz 76 (1).

Howells, R.G., L.F. Burlakova, A.Y. Karatayev, R.K. Marfurt, and R.L. Burks. 2006. Native and introduced Ampullariidae in North America. Pages 73-112 in Joshi, R.C. and L.S. Sebastian, eds. Global advances in the ecology and management of golden applesnails. Philippine Rice Research Institute. Munoz, Ecija.

Morrison, W.E., and M.E. Hay. 2011. Feeding and growth of native, invasive and non-invasive alien apple snails (Ampullariidae) in the United States: invasives eat more and grow more. Biological Invasions 13:945-955. http://www.springerlink.com/content/511320h258vj3h25/fulltext.pdf.

Rawlings, T.A., K.A. Hayes, R.H. Cowie, and T.M. Collins. 2007. The identity, distribution, and impacts on non-native apple snails in the continental United States. BMC Evolutionary Biology 7:97. http://www.biomedcentral.com/1471-2148/7/97.

Rodrigues, L.C., I.F. da Silva Lima, and H.M. Cascon. 2025. Zootechnical performance of juvenile Pomacea haustrum (Revee, 1856) under different diets and salinities. Revista Cienca Agronomica 56:e202291993. https://www.scielo.br/j/rca/a/CKxMcGphXkRjb7dkHZFRDcr/?lang=en.

U.S. Fish and Wildlife Service (USFWS). 2018. Titan applesnail (Pomacea haustrum) ecological risk screening summary. https://www.fws.gov/sites/default/files/documents/Ecological-Risk-Screening-Summary-Titan-Applesnail.pdf.

Other Resources:
US Fish and Wildlife Service Ecological Risk Screening Summary for Pomacea haustrum

Author: Stratton, L.D.

Peer Review Date: 4/10/2025

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.