The segment above (from the BBC series Life Story) shows hermit crabs exchanging shells in a rather remarkable way. I wondered if this had been documented in scientific literature. I’ve read a fair number of papers on hermit crab shell choice, but not this queuing behaviour. And with a little searching in Google Scholar, voila!
Lewis SM, Rotjan RD. 2009. Vacancy chains provide aggregate benefits to Coenobita clypeatus hermit crabs. Ethology 115(4): 356-365. http://dx.doi.org/10.1111/j.1439-0310.2009.01626.x
Rotjan RD, Chabot JR, Lewis SM. 2010. Social context of shell acquisition in Coenobita clypeatus hermit crabs. Behavioral Ecology 21(3): 639-646. http://beheco.oxfordjournals.org/content/21/3/639.abstract
Hat tip to Emily Anthes and io9.