Euglandina rosea
(rosy predator snail)

Pictures

Top of page

Identity

Top of page

Preferred Scientific Name

• Euglandina rosea Férussac, 1821

Preferred Common Name

• rosy predator snail

Other Scientific Names

• Achatina rosea Férussac, 1821
• Glandina parallela Binney, 1878
• Glandina truncata Say, 1831
• Helix rosea Férussac, 1821
• Polyphemus glans Say, 1818

International Common Names

• English: Cannibal snail; Rosy wolf snail

Summary of Invasiveness

Top of page

E. rosea has had a negative impact on native snail species in the countries into which it has been introduced. It has been responsible for the dramatic decline or eradication of many endemic species, particularly Partulidae and Achatinellinae (Cowie, 2001, 2003). On the Society Islands, French Polynesia, alone, only five of the original 61 species remain (Coote and Loeve, 2003). E. rosea is listed on the IUCN ISSG among 100 of the world's worst invasive species and IUCN has condemned its deliberate introduction as a biological control agent.

Taxonomic Tree

Top of page

• Domain: Eukaryota
•     Kingdom: Metazoa
•         Phylum: Mollusca
•             Class: Gastropoda
•                 Subclass: Pulmonata
•                     Order: Stylommatophora
•                         Suborder: Sigmurethra
•                             Unknown: Achatinoidea
•                                 Family: Spiraxidae
•                                     Genus: Euglandina
•                                         Species: Euglandina rosea

Notes on Taxonomy and Nomenclature

Top of page

E. rosea is a pulmonate snail, native to the south-eastern part of North America. Pilsbry (1946) summarizes the nomenclature of Euglandina and states that the type specimen figured by Férussac was a form from Florida, USA, collected by Say on the sea islands of Georgia and in Florida. The type locality is thus given as St. Augustine, one of Say's collection sites.

Description

Top of page Eggs

The eggs are oval, 4.25 mm long and 3-3.25 mm wide. The eggshell is rough-surfaced, quite porous, brittle and hard. The young must rasp an opening in the shell, using the radula, before they are able to emerge from the egg. Incubation took 30-40 days with a success rate of 85-100% under artificial conditions in Taiwan (Chiu and Chou, 1962), suggesting a considerable reproductive potential. This is borne out by censuses carried out on populations introduced to Pacific islands in the late 1960s (Mead 1961).

Adults

The shell is oblong, glossy surfaced, with a regularly tapering spire and a blunt apex. There are approximately six whorls. The first three whorls are smooth; the rest are irregularly sculptured with fine longitudinal grooves, occasional deeper grooves, but no spiral lines. The spire and apex is usually a pink shade, usually fading to buff-pink in dead specimens or in scientific collections. The aperture is more than twice as long as it is wide, with a thickened lip and pink interior. Shell length varies from 49 to 76 mm, diameter from 21 to 27.5 mm.

The living animal is an active and rapacious hunter. They move rapidly and actively hunt their prey by following slime trails. The dorsal tentacles have a distinctive lobe beneath the eye, whilst the ventral tentacle is somewhat shorter, with no lobe. The oral lips are highly active, have a chemosensory role, are much longer than the ventral tentacles and give the snail a distinctive 'moustachioed' appearance (Cook, 1985b).

Distribution

Top of page

The distribution of E. rosea and status of the various introduced populations has been summarized by Griffiths et al. (1993) and by Civeyrel and Simberloff (1996). Surviving populations (the date of introduction is given in parentheses) can be found in Bermuda (introduced 1958-60), Grand Comorro (1970), Guam (1958), Hawaii (1955), Madagascar (1970), Mauritius (1959), Micronesia (?), Moorea (1977), New Caledonia (1974-78), New Guinea (1959-61), Okinawa (1958-61), Palau (1960), Réunion (1966), Rodrigues (ca 1961), Saipan (?), Samoa (1980-84), Seychelles (1966), Society islands (1974), Ta'u (Samoa) (1992) and Vanuatu (1973-74) (Civeyrel and Simberloff, 1996). Cowie (2000, 2003) has updated the distribution of E. rosea, noting that it is also found in Indonesia, Kiribati and the Solomon Islands.

Distribution Table

Top of page

The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.

History of Introduction and Spread

Top of page E. rosea was deliberately introduced into Bermuda (in 1958-1960), French Polynesia (in 1974-1977), Guam, American Samoa (1980), Hawaii (in 1955-1958) and the Northern Mariana Islands as a biological control agent against Achatina fulica. It is probable that E. rosea was similarly introduced into the other countries where it is listed as an exotic species (Cowie, 2003). In all cases it has failed as a biological control agent but succeeded in impacting upon native mollusca, frequently resulting in the loss of endemic species. E. rosea was introduced into New Caledonia (1974-1978) and Vanuatu (1973). It was also introduced into Papua New Guinea (1952-1961) but failed to establish there (Cowie, 2000).

Risk of Introduction

Top of page

The potential for further spread of E. rosea is primarily through further deliberate introductions. The IUCN ISSG has listed E. rosea amongst 100 of the world's worst invasive species and condemned its use as a biological control agent. However, Cowie (2000) stated that intense pressure from Pacific Islanders to resolve the problem of Achatina fulica may lead to its deliberate official or unofficial release. Increasing trade between countries could also lead to the introduction of E. rosea into new habitats (Cowie, 1998).

Habitat

Top of page E. rosea can be found living in both disturbed and undisturbed areas, natural and planted forests, shrubland and urban areas (Cowie, 2003). Binney (1885) states that Euglandina is somewhat aquatic, that it is found on the sea islands of Georgia and the keys and everglades of Florida, USA. Larger snails are found in the most humid environments, whilst those found in drier areas are substantially smaller. Euglandina is generally found amongst the undergrowth at ground level, but is capable of tree climbing and may be found in large numbers above ground level under certain situations (Griffiths et al., 1993). Although Euglandina prefers moist conditions, it was found to be capable of aestivation to withstand dry periods and can hibernate during the winter in Taiwan (Chiu and Chou, 1962). Griffiths et al. (1993) collected Euglandina from four distinctly different habitat types in Mauritius; it was least common in the drier areas of the north and west and in primary forest, although they suggested that this was due to predation or competition from endemic snails, rather than unsuitable habitat.

Hosts/Species Affected

Top of page E. rosea is native to the south-eastern USA, and is found in South Carolina, Georgia, Florida, Alabama, Mississippi and Louisiana. In 1955 it was introduced to the Hawaiian islands in an attempt to control the spread of the introduced herbivorous snail Achatina fulica (Mead, 1961) and from there it was introduced to a number of Pacific Islands (Griffiths et al., 1993; Civeyrel and Simberloff, 1996; Cowie, 1998, 2000, 2003). However, it has proven to be ineffective against Achatina and has instead decimated the native snail populations of the islands to which it was introduced (Murray et al., 1988; Cowie, 2001, 2003; Coote and Loeve, 2003). Griffiths et al. (1993) investigated the stomach contents of Euglandina on Mauritius and were unable to identify Achatina in any of the samples investigated. In 1988 the IUCN (The World Conservation Union) passed a resolution which urged government agencies to stop any further introduction of Euglandina for biological control purposes.

Biology and Ecology

Top of page

Reproductive Biology

E. rosea is an obligate cross-fertilizing hermaphrodite. Its mating behaviour has been described by Ingram and Heming (1942), Chiu and Chou (1962), and most recently by Cook (1985a). The snail lives for about 2 years and adult snails lay 25-35 eggs at each oviposition, producing approximately 100 eggs during their lifespan (Chiu and Chou, 1962). The snail is primarily nocturnal and is usually ground living, but will climb trees (Griffiths et al., 1993) and enter shallow water courses in pursuit of prey (Kinzie, 1992).

Prey Detection and Feeding Behaviour

Several aspects of the feeding behaviour and prey detection in Euglandina have been described by Ingram and Heming (1942), Cook (1985a, b; 1989a, b) and Kinzie (1992). Euglandina appears to detect its prey by following slime trails (Cook, 1985b; Clifford et al., 2003), which it does more than 80% of the time (Clifford et al., 2003) or by detecting dissolved substances in water (Kinzie, 1992). Chemical components of the mucus and perhaps the shell, together with the physical dimensions of the shell are the most important determinants of prey suitability (Cook, 1989a, b). Euglandina will also consume randomly encountered static prey. When contact is made with the prey, it is usually picked up with the foot and swallowed whole, or the soft parts of the prey are extracted from the shell. Which feeding technique is utilized depends on a number of factors, including the relative sizes of predator and prey and probably also the nutrient status of the predator (Cook, 1985b; 1989b). In gastropods of any given species, Euglandina showed a clear preference for the smaller individuals (Chiu and Chou, 1962; Cook, 1989b).

Notes on Natural Enemies

Top of page

Hadfield et al. (1993) suggested that rats (Rattus rattus, R. norvegicus) might have a significant effect on Euglandina populations, especially as it is typically a ground-dwelling snail.

Plant Trade

Top of page

Impact Summary

Top of page

Impact

Top of page

The economic impact of E. rosea is difficult to determine. Whilst it appears to have had no effect on the control of Achatina, it has had a devastating impact on the endemic snail faunas of many of the islands to which it has been introduced (Hadfield et al., 1993; Cowie, 2001; Gerlach, 2003). This in turn has been damaging to scientific investigations of those species, notably the work carried out by Clark and others on the genetic diversity of Partula on Moorea (Civeyrel and Simberloff, 1996). A considerable international effort is underway to conserve these threatened island snails, which includes captive breeding programmes and the creation of reserves free from Euglandina.

Threatened Species

Top of page

Risk and Impact Factors

Top of page Impact mechanisms

• Predation

Detection and Inspection

Top of page Live snails might be found aestivating on transported vegetation or amongst leaf litter or debris at the base of plants. Eggs might be found buried in soil at the bases of plants. Most introductions have been deliberate.

Similarities to Other Species/Conditions

Top of page The long and active oral lips and lobe below the eye on the dorsal tentacle make them highly distinctive animals; they are not similar to any other snails on the islands to which they have been introduced.

References

Top of page

Auffenberg K, Stange LA, 1986. Snail-eating snails of Florida. Entomology Circular, Florida Department of Agriculture and Consumer Services, Division of Plant Industry, No. 285:4 pp.; [6 fig.].

Binney WG, 1885. A manual of north American land snails. Bulletin of the United States National Museum, 28:348-350.

Chiu SC, Chou KC, 1962. Observations on the biology of the carnivorous snail Euglandina rosea Ferussac. Bulletin of the Institute of Zoology, Academia Sinica (Taipei), 1:17-24.

Civeyrel L, Simberloff D, 1996. A tale of two snails: is the cure worse than the disease?. Biodiversity and Conservation, 5(10):1231-1252.

Clifford KT, Gross L, Johnson K, Martin KJ, Shaheen N, Harrington MA, 2003. Slime-trail tracking in the predatory snail, Euglandina rosea. Behavioural Neuroscience, 117(5):1086-1095.

Cook A, 1985a. The courtship of Euglandina rosea Férussac. Journal of Molluscan Studies, 51:211-214.

Cook A, 1985b. The organisation of feeding in the carniverous snail Euglandina rosea Férussac. Malacologia, 26:183-189.

Cook A, 1989. Factors affecting prey choice and feeding technique in the carnivorous snail Euglandina rosea Ferussac. Journal of Molluscan Studies, 55(4):469-477.

Cook A, 1989. The basis of food choice by the carnovorous snail, Euglandina rosea.. Monograph - British Crop Protection Council, No. 41:367-372; [In Slug and Snails in World Agriculture, Guildford, 10-12 April 1989].

Coote T, Loeve E, 2003. From 61 species to five: endemic tree snails of the Society Islands fall prey to an ill-judged biological control programme. Oryx, 37(1):91-96.

Cowie RH, 1998. Patterns of introduction of non-indigenous non-marine snails and slugs in the Hawaiian Islands. Biodiversity and Conservation, 7(3):349-368.

Cowie RH, 2000. Non-indigenous land and freshwater molluscs in the islands of the Pacific: conservation impacts and threats. In: Sherley G, ed. Invasive species in the Pacific: A technical review and draft regional Strategy. SPREP, 143-166.

Cowie RH, 2001. Can snails ever be effective and safe biocontrol agents? International Journal of Pest Management, 47(1):23-40.

Cowie RH, 2003. ISSG Global Invasive Species Database. http://issg.appfa.auckland.ac.nz/database/species/search.

Gargominy O, 2008. Beyond the alien invasion: a recently discovered radiation of Nesopupinae (Gastropoda: Pulmonata: Vertiginidae) from the summits of Tahiti (Society Islands, French Polynesia). Journal of Conchology, 39(5):517. http://www.conchsoc.org/resources/show-abstract-39.php?id=%20%20%20%20%20%20%20%20%20%20%20%20150

Gerlach J, 2003. Predator, prey and pathogen interactions in introduced snail populations. Animal Conservation, 4(3):203-209.

Griffiths O, Cook A, Wells SM, 1993. The diet of the introduced carnivorous snail Euglandina rosea in Mauritius and its implications for threatened island gastropod faunas. Journal of Zoology, 229:79-89.

Hadfield MG, Miller SE, Carwile AH, 1993. The decimation of endemic Hawai'ian tree snails by alien predators. American Zoologist, 33:610-622.

Ingram WM, Heming WE, 1942. Food, eggs and young of the carnivorous snail Euglandina rosea (Férussac). Zoologica, 27:81-84.

Kinzie III RA, 1992. Predation by the introduced carniverous snail Euglandina rosea (Ferussac) on endemic aquatic lymnaeid snail in Hawaii. Biological Conservation, 60:149-155.

Mace GM, Pearce-Kelly P, Clark D, 1998. An integrated conservation programme for the tree snails (Partulidae) of Polynesia: A review of captive and wild elements. Journal of Conchology, Supplement 2:89:96.

Mead AR, 1961. The Giant African Snail: A Problem in Economic Malacology. Chicago, USA: University of Chicago Press, 257 pp.

Murray J, Murray E, Johnson MS, Clarke B, 1988. The extinction of Partula on Moorea. Pacific Science, 42(3-4):150-153.

Pilsbry HA, 1946. Land Mollusca of North America (North of Mexico). Monograph no.3. Philadelphia, USA: The Academy of Natural Sciences of Philadelphia.

US Fish and Wildlife Service, 2006. In: Final Recovery Plan for the Newcomb's Snail (Erinna newcombi). US Fish and Wildlife Service, 61 pp.. http://ecos.fws.gov/docs/recovery_plan/060918b.pdf

US Fish and Wildlife Service, 2013. In: Endangered and Threatened Wildlife and Plants; Determination of Endangered Status for 38 Species on Molokai, Lanai, and Maui; Final Rule. 78(102) US Fish and Wildlife Service, 32014-32065. https://www.gpo.gov/fdsys/pkg/FR-2013-05-28/pdf/2013-12105.pdf

US Fish and Wildlife Service, 2014. In: Species assessment and listing priority assignment form: Eua zebrina. US Fish and Wildlife Service, 20 pp.. http://ecos.fws.gov/docs/candidate/assessments/2014/r1/G0BJ_I01.pdf

US Fish and Wildlife Service, 2014. In: U.S. Fish and Wildlife Service species assessment and listing priority assignment form: Ostodes strigatus. US Fish and Wildlife Service, 9 pp.. http://ecos.fws.gov/docs/candidate/assessments/2014/r1/G0A5_I01.pdf

Distribution Maps

Top of page