Carnivorous slugs from Singapore

If you wander into the garden on a rainy night, make sure you've got something on your feet. It's bad enough standing on a slug while you're wearing shoes, but in bare feet, the slime and viscera will ooze between your toes like the tinea cream from Hell.

In most parts of the world that's an unfortunate accident. Just don't try it in Singapore — because the slugs will bite your toes off.

Okay. I might have indulged in a spot of hyperbole there. Well, outright lying is another way of putting it. Singaporean slugs won't snack on your foot ... unless you're a snail. And if you are, those slugs won't just stop there.

A paper in the latest edition of Nature in Singapore documents the recent discovery of two species of carnivorous slugs of the genus Atopos (Rathouisiidae) on the island. Atopos is known from Peninsular Malaysia, Sumatra, Borneo, New Guinea and north-eastern Australia, but had not previously been recorded from Singapore.

The first animal turned up in a location that most tropical zoologists will recognise as a rich source of invertebrates, frogs and geckos — a toilet cubicle. The second came from leaf litter.

While in captivity, Atopos Species 2 fed on small snails. It held the shells aperture-upward with the front of its foot and nom-nom-nomed its way down. (Download a PDF of the paper for colour photos. Link below.) Bornean Atopos specialising in Opisthostoma-vory are known to tailor their approach to the size of the prey. Small snails are tackled via the aperture in the manner of Species 2. Larger ones have the shell scraped away to allow access through the spire. This behaviour is thought to drive the evolution of shell ornamentation in Opisthostoma, which all look as if they've been designed by Gaudi.

Whether the Singaporean slugs do the same to their larger prey is yet to be determined because Atopos Species 2 turned up its nose proboscis at offerings of Subulina octona, a tall-spired snail. Ain't it always the way?

There's still much to learn about these enigmatic molluscs. But, although we can't say for sure, there's a good chance that they won't chew off your toes.

Reference
Tan, SK & Chan, S-Y. (2009) New records of predatory slugs from Singapore with notes on their feeding behaviour. Nature in Singapore 2: 1–7. (1.03 MB)

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Thanks to Sow-Yan Chan.