Monday, September 11, 2006

Slimier snails slither slower

New Scientist reports:

If you are into betting on snail races, here's a tip: put your money on the least slimy snail. Making mucus requires energy, and it turns out that snails slither best when they produce as little as possible of just the right kind of goo.

Snails, slugs and other gastropods move by using their muscles to generate travelling waves of stress in the thin layers of mucus they lay down. Because it takes more energy to produce the mucus than to power their muscles, they need to get by with the thinnest layer possible.

The key to their success seems to be an unusual physical property of the mucus. When Eric Lauga and Annette Hosoi of the Massachusetts Institute of Technology modelled the locomotion of gastropods mathematically, they found that the creatures exploit a phenomenon called "shear-thinning" - a fall in the viscosity of the mucus when it is between two surfaces that are moving relative to one another.

"Shear-thinning allows the gastropod to crawl while using the least amount of fluid," Lauga says.

The viscosity of most liquids does not change under such conditions, and some become more viscous between moving surfaces. The viscosity of snail and slug mucus, by contrast, drops by a factor of more than 1000 under biologically realistic conditions.


Major Look said...

And another tip...
When betting on Greyhound races, put your money on the dog that has a poo or a wee before the race, they weigh less!

brett jordan said...

Thank you Mr Look for your thoughtful and clever suggestion. It will save me hours measuring the thickness of grehound's slime trails, not to mention the funny looks I get from the people at the track.

ConradGempf said...

See... who said blogs weren't useful?