Even though we are taught from our very first biology class the basic relationship between predator and prey, it still amazes me to this day how specific some of these relationships can be. In the case of Pareas iwasakii, an escargot aficionado, the snail eating snake may begin to find it difficult to unscrew the little gastropods from their calcium carbonate homes. While the delicasy is in no short supply, the snails are making a simple change that will take much time and energy on the snakes' behalf to overcome. Most terrestrial molluscs like the common land snail have a dextral shell that spirals to the right, or clockwise. P. iwasakii has in turn has developed a jaw structure designed specifically to pluck the snail from its shell. A study done by Masaki Hoso on 28 snakes found there to be on average about 6.5 more teeth on the right side than on the left (17.5 left, 24.9 right). The snakes' asymmetrical jaw allows it to "mandable walk" its toothy jaw into the snails shell. These left to right motions work flawlessly on a dextral shell, however, snails such as S. caliginosa have answered this unfair advantage by evolving sinistral shells, or shells that whirl to the left (counter-clockwise). This simple change in anatomy doesn't cost the snail much in terms of energy, but the snake cannot coerce the snail from its protective shell not matter how hard it tries. This text book case of natural selection becomes important when we try to understand the ecological arms race because it shows us the degree to which different species will evolve inorder to live with one another. To me, this is just another one of Mother Nature's incredible ways of solving a problem that will haunt the animal kingdom until the end of time (December of this year perhaps...?)
A. P. iwasakii feeding
B. Mandable of Pareas iwasakii- pre hatch
Bars: 10 mm. Image credit: Nature Communications, doi:10.1038/ncomms1133
A video of a successful hunt and unsuccessful hunt:
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ARTICLE INFO
The Evilutionary Biologist: ALL SCIENCE, ALL THE TIME
Author: John Dennehy
1 comment:
Very cool!
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