Charles Darwin’s voyage on the Beagle not only led him to visit a number of Indian Ocean islands but helped to sustain a life-long interest in the more unusual flora and fauna of the far-flung coral atolls. He was particularly fascinated by, but a little sceptical about, the notion of the coconut-eating crab.
He discussed the issue in his 1860 account of his travels:
I have before alluded to a crab which lives on the cocoa-nuts; it is very common on all parts of the dry land, and grows to a monstrous size: it is closely allied or identical with the Birgos latro. …. It has been stated by some authors that the Birgos crawls up the cocoa-nut trees for the purpose of stealing the nuts: I very much doubt the possibility of this; but with the Pandanus the task would be very much easier. I was told by Mr. Liesk that on these islands the Birgos lives only on the nuts which have fallen to the ground.Captain Moresby informs me that this crab inhabits the Chagos and Seychelle groups, but not the neighbouring Maldiva archipelago.