08 December 2010

Vertigo pygmaea crawling

Lately, I have been interested in the relative dimensions of snails' feet and shells. What factors influence and control the size of a snail's foot relative to the size of its shell? The shape of the shell seems to matter. I have noticed in tiny species whose shells are longer than they are wide, the length of the foot is close to that of the shell. Here is a Vertigo pygmaea from my backyard.


The white line is equal in length to the snail's foot, while the blue line to its shell. The latter was about 1.9 mm long*. The ratio of the lengths of the blue and white lines (foot/shell) was 0.80.

This previous post was also about this subject and featured another example. Expect more in the future.


*I wrote about the shell lengths of Vertigo pygmaea in this post.

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