Mike Lyle wrote:

[-]


I used to have a blank north-facing house wall. Where did snails think
(if "think" is the right word) they were going when I found them
fifteen feet up and still climbing? I've often wondered how such
behaviour could possibly be adaptive.

Our north-facing first floor window looks into a neighbour's tree, and I
often see snails on the upper branches of that. If memory serves, in hot
weather temperatures at/near ground level in full sun are high because
of solar radiation absorbed by the soil. Snails are programmed to climb
to find coolth away from ground level, so may climb even north walls if
the weather is warm; alternatively there's a reasonable crop of algae
available on your wall/that tree. Or perhaps they're just stupid :-)

regards
sarah


--
Think of it as evolution in action.