Sunday, April 16, 2006

Slugs and snails and...woodlice

I opened the Spring 2006 edition of the NATURAL WORLD - magazine of the Wildlife Trust of which the Hodmandods are interested if not active members and found a feature called 'Secrets of the soil-dwellers'. Two of the animals featured were the Tiger Slug and the Garden Snail. Consequently I have found yet more fascinating information on the mating rituals of these molluscs (which are related to octopus and giant squid, apparently - although I should have guessed since they have the same type of squishiness (technical term)).

According to Brian Eversham, who is a national authority on beetles and molluscs, the Tiger slug, at 20 cm or 8 inches long is the biggest of the British slugs. They are famous for dangling from a rope of slime to mate (which I guess beats a chandelier) the more aggressive members of the species biting off their partner's genitalia, dropping to the ground and proceeding to eat them - which makes me think of James Bond, though I can't quite understand why. I was thinking of doing a 101 words story based on this but I think it would be a little too sordid even for me.

As for the snails Brian Eversham reports that some garden snails have hairy shells. Obviously I am going to have to inspect my snails more closely because I haven't yet come across these yet. However I have come across two other pieces of snail information recently; that some snails are sinister because they have left-handed spirals - and crabs find these more difficult to eat, although this has not meant that they have become more plentiful over time; and that some snails are venomous and are rather like a pharmaceutical company on one slithering leg since they are always developing new poisons to outwit their prey. These poisons act on the nervous system and one of these compounds has already found a use as a painkiller and the rest are being investigated as being of potential benefit in the treatment of brain diseases such as Parkinson's and Altzheimers.

Other interesting animals mentioned in the NATURAL WORLD article are woodlice which are aquatic and carry their water around with them as a thin film on their underside. They breathe through gills and so if they dry out they suffocate like a fish out of water. Now when I was studying biology at school and when I taught it myself there was one biological experiment that always worked - put a heap of woodlice in the middle of a gauze-covered dish that had been divided up into quarters - one dark and damp, one dark and dry, one light and wet, one light and dry, and watch to see what would happen. The poor little animals would always go and huddle in the damp dark section. Conclusion - woodlice prefer damp dark conditions. But I know now that in fact they were only saving themselves from suffocation. It strikes me as a little cruel.


Blogger Jonathan Wonham said...

Interesting about the genitalia-eating slugs. How do they know it's the aggressive ones that do this? It might just be the hungry ones...

Sun Apr 16, 10:16:00 pm  
Anonymous Anonymous said...

Jonathan: good point. The aggressive bit is just my invention so you may well be right. Apparently the slug's eggs 'look disturbingly like sago pudding' which kind of ties in somehow, I guess.

Tue Apr 18, 12:05:00 pm  
Blogger Robert Nordsieck said...

Hi there, there is some comfusion: The mating on a slime rope is Limax maximus, the biting off of genitalia is a North American slug species of the Ariolimax genus! Regards Robert

Tue Jun 17, 08:30:00 am  
Blogger Clare Dudman said...

Thanks Robert! The Limax maximus is obviously the James Bond of snails! I'm quite reassured to know that such heroism is not so ill-rewarded after all.

Tue Jun 17, 08:46:00 am  

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