SSS 2012-08-16

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Lots of animals build homes for protection. Think Beaver¹ lodges² and termite³ mounds⁴. Hermit⁵ crabs⁶, on the other hand, inhibit⁷  hand-me-down homes. But they remodel⁸ them first, carving⁹ out shells to make them lighter¹⁰ and twice spacious¹¹ as the originals. Those creature comforts come at cost though- because hollowed- out shells can be more easily crashed in the jaws¹² of predator¹³.  

 

Researchers wanted to find out if hermit crabs take that crucial detail into consideration. So they gave over a thousand new sea snail¹⁴ shells to hermit crabs in Costa Rica. A year later they recovered the used ones. Then they crushed them.

 

As expected, remodeled shells broke twice as easily as new ones. But the strength it took to smash them was still just a bit more than local raccoons can master, meaning crabs may remodel with their predator's bite in mind. The results are in the Journal of Royal Society Interface¹⁵.

 

The benefits of the fixer-upper larger home are many. Females lay more eggs, males grow burlier and crabs can avoid nasty squabbles with competitor for a real estate upgrade. And they don't even have to shell out much. 

 

Thanks for the minute for scientific American sixty seconds science. I'm Christopher Intagliata.  

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