All carnivorous snails have those mustache-like lobes sticking out from either side of their heads. Here's a document I found on the California Academy of Sciences' webpage that explains more.
Q - Do carnivorous snails have special features in common?
A – The common carnivore features are: comparatively few, but very long and slender radular teeth (for grasping and tearing); a somewhat enlarged and concentrated nervous system (to interpret data); development of lobes either on the tentacles or near the mouth that act as chemical sensors (to locate prey); often a slender and quite long elongated body that can be stretched far in front of the shell edge (to enter shell of prey); and an expanded foot gland (for swift pursuit).
. . . Q - How does the predator kill its prey?
A - Euglandina rosa and Edentulina ovideus enter the aperture of the prey. An anesthetic may be used. The New Zealand Paryphanta eats worms live and whole, kind of like spaghetti.
Post by Robert Nordsieck on Jul 8, 2006 22:50:43 GMT
not all carnivorous snails have got those typically extended lips, like Euglandina does. Among those, who do, for example are the South African cannibal snails (Natalina). According to Herbert & Kilburn: "Field Guide to the Snails and Slugs of Eastern South Africa" those are especially fierce predators, attacking smaller snails and devouring them piecemeal, with lots of writhing and foaming on the victim's side. The book even mentions those snails might possibly bite your finger, if you pick them up.
There are, however, other carnivorous snail species, such as the Dalmatian predator (Poiretia cornea), who do not have the extended lips. Poiretia, by the way, has a special method to overpower its prey: It dissolves the shell wall with a self-produced acid!
Other carnivorous snails, occurring in Britain, are the Testacellidae, looking like slugs with a shell at the tail tip, too tiny to withdraw into. Those snails hunt earthworms underground. In that they ressemble the Paryphanta from New Zealand. There are also the Daudebardiidae, which are similar, though not directly related.