I’m really not sure what to make of this project to make artificial homes for hermit crabs. My first reaction is, “Wow, that’s a really cool thing to do!” On second thought, though, the following paragraph gives me…well, second thoughts.

Being much lighter than calcium carbonate, these new houses do not take as much energy to carry during locomotion. Plastic is also structurally strong, which affords large areas of internal space in the new structures. This results in the greater internal volume-to-weight ratio that the crab prefers. Of additional benefit is the longevity of this material coupled with the way these crabs recycle and share their shelters.

The fact that hermit crabs might come to prefer these artificial shells to the natural kind because of these differences raises some nasty issues of interfering with natural growth and mating patterns, and perhaps even fostering a level of dependence. That might be outweighed by the importance of compensating for a “housing shortage” that might itself be the result of human activity – a hermit crab using one of these shells is a lot better than a hermit crab using a glass jar as described in the article – but I think I’d feel better about the project if the artificial shells had been more rigorously designed to resemble their natural counterparts.

The part about hermit crabs lining up for hand-me-downs is still cool, though. I’d love to see that.