Rosy Wolf Snail (Euglandina rosea), adult specimen.
Picture by courtesy of: Jim Miller, Jacksonville Shell Club.
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Rosy Wolf Snail (Euglandina rosea), adult specimen. Picture by courtesy of: Jim Miller, Jacksonville Shell Club. |
Wolf snails are are part of the mainly neotropic land snail family of Oleacinidae, whose area of distribution spread from Southern and Central America up into the South Eastern United States. Some species, though, also settled in the area of the Mediterranean.
In Florida, for example, the rosy wolf snail, Euglandina rosea (Férussac 1821), may be found, a predator snail about 10 cm long, in contrary to other predator snails a specialised snail-eater.
A European member of the family is the Dalmatian predator (Poiretia cornea), that can be found in the Mediterranean and especially hunts for small operculate land snails (like the round-mouthed snail, Pomatias elegans).
Euglandina and Poiretia both even bear an external resemblance: They share an elongate oval shell with an visibly extended last whorl and a strikingly large aperture.
 A wolf snail's (Euglandina rosea) head. Picture by courtesy of: Jim Miller, Jacksonville Shell Club. |
Looking closely at a wolf snail's head, it appears to have three pairs of tentacles. The longer eye stalks can easily be seen, as well as the shorter tentacle pair below. Below these there appears to be a third pair of tentacles. Only, this is actually not a pair of tentacles, but the wolf snail's greatly elongated lips.
A terrestrial snail's lips are full of chemical sense cells, by the help of which the snail can search the ground for food. In the case of the wolf snail, the lips are used to follow the prey's scent along its slime trace. Which a wolf snail does, like a wolf follows the scent of its prey, hence the snail's name. Only in the case of the wolf snail, it is more precisely the taste, not the scent, it follows.
 Euglandina rosea on the title of „Science” (Vol. 285, Sept. 99). Source: R.H. Cowie. |
From another snail's slime trace the wolf snail also gains information on whether the snail is a potential meal rather than a fellow wolf snail. Which basically makes not much of a difference, as wolf snails also are cannibals.
On pursuit of its prey the wolf snail does not move at a proverbial snail's pace, but at double or triple that speed. It follows its prey up trees and even for certain distances under water.
As wolf snails are not only snail-eaters, but also cannibals, even the young snails already feed on eggs and their siblings. Generally wolf snails prefer smaller snails, that can be eaten whole with the shell. The advantage for the wolf snail is obvious – so it can eat the snail and consume calcium carbonate from the shell. The American malacologist G. Lee reports to have found at least 13 snail shells in a dissected specimen of Euglandina rosea. ("Shells are where you find them").
 Euglandina feeds on a Bradybaena similaris. Picture by courtesy of: Bill Frank, Jacksonville Shell Club. |
While it eats smaller snails whole, larger prey is eaten piecemeal. The wolf snail's slender body enables it to reach the innermost parts of the prey's shell and to eat it until the last portion.
Wolf snails also eat slugs. In experiments it has been found that small garden slugs (Deroceras) managed to evade a wolf snail attack by hectically waving the tail, obviously trying to stop it from getting a grip with the radula.
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Partula
suturalis, one of 56 species of tree snails originally endemic to the Society Islands, today considered extinct.
Source: London Zoo.
Man has introduced wolf snails as a biological weapon against the giant African land snails (Achatina fulica) that had previously been introduced to several Pacific islands (Hawaii, Mariana islands, Polynesia) for economical reasons. Instead to eat the giant African snails, that had become a large pest problem for local agricultural areas, the wolf snails preferred to hunt the smaller endemic tree snails (Partula, Achatinella, among others). Those had no endemic predator enemies and therefore were not accustomed to evading predator snails. Today many of those tree snail species are estimated to be extinct and must be though to be invariably lost. As wolf snails' feeding behaviour was already well known and documented, the consequences of such an intrusion into an endemic ecological system should have been predictable. Alas, the local authorities disregarded the warnings of worried malacologists and ecologists.
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