These crabs are called by the scientists Birgos latro, by the Marquesans tupa, by the Paumotans kaveu, and by the Tahitians, ua vahi haari. It was a never-failing entertainment on my walks in the Paumotas to observe these great creatures, light-brown or reddish in color, more than two feet in length, stalking about with their bodies a foot from the ground, supported by two pairs of central legs. They can exist at least twenty-four hours without visiting the water, of which they carry a supply in reservoirs on both sides of the cephalothorax, keeping their gills moist.
A Marquesan home on a paepae
Isle of Barking Dogs
They live in large deep burrows in the cocoanut-groves, which they fill with husks, so that the natives often rob them to procure a quick supply of fuel. These dens are contrived for speedy entry when pursued. Terrifying as they appear when surprised on land, they scuttle for safety either to a hole or to the sea, with an agility astounding in a creature so awkward in appearance. Though they may be seen about at all hours of the day, they make forays upon the cocoanuts only at night.
Darwin first saw these creatures in the Indian Ocean, and said that they seek the sea every night to moisten their branchiae. The young are hatched and live for some time on the sea-coast, venturing far from water only as they grow older. Darwin said that their feat in entering the cocoanut “is as curious a case of instinct as was ever heard of, and likewise of adaptation in structure between two objects apparently so remote from each other in the scheme of nature, as a crab and a cocoanut-tree.”
When darkness descends and all is quiet, the robber crab ascends the tree by gripping the bark with his claws. The rays of my electric flash-light have often caught him high over my head against the gray palm. Height does not daunt him. He will go up till he reaches the nuts, if it be a hundred feet. With his powerful nippers he severs the stem, choosing always a nut that is big and ripe. Descending the palm, he tears off the fibrous husk, which, at first thought, it would seem impossible for him to do. He tears it fiber by fiber, and always from that end under which the three eye-holes are situated. With these exposed, he begins hammering on one of them until he has enlarged the opening so that he can insert one of the sharp points of his claw into it. By turning his claw backward and forward he scoops out the meat and regales himself luxuriously.