Lots of animals build homes for protection. Think Beaver lodges and termite mounds. Hermit crabs, on the other hand, inhibit  hand-me-down homes. But they remodel them first, carving out shells to make them lighter and twice spacious as the originals. Those creature comforts come at cost though- because hollowed- out shells can be more easily crashed in the jaws of predator.  

 

Researchers wanted to find out if hermit crabs take that crucial detail into consideration. So they gave over a thousand new sea snail 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 Interface.

 

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.