The robber crab, Birgus latro, is the world’s largest land-dwelling arthropod, with a weight reaching 4 kg and a length of over half a meter. Robber crabs are perhaps most famous for their ability to climb tall palm trees in search of coconuts, which they later are able to crack open with their massive claws. These crabs are fully adapted to a life on land, and will actually drown if submerged in water. The robber crab’s transition from sea to land has been accomplished through numerous, and in many cases far-reaching, adaptations. A question not previously addressed is how the robber crabs have adapted to olfaction in their new environment – an intriguing question, as the sense of smell needs to operate under very different conditions in air compared to water.

In an article in Current Biology, Marcus Stensmyr and Bill S. Hansson from the Swedish University of Agricultural Sciences, together with colleagues from Lund University, Sweden and University of New South Wales, Australia, show that these impressive crabs not only have a functional sense of smell, but that the olfactory system they have developed is in fact highly sophisticated and sensitive. Moreover, the crabs have managed this evolutionary feat by adopting olfactory strategies similar to those of insects. Remarkably, the similarities between the crab and insect olfactory systems extend to functional, behavioral and structural characteristics. The “insect nose” of the robber crab is a striking example of convergent evolution, and nicely illustrates how similar needs of very distantly related organisms may cause similar end results

Contact: Dr Bill S. Hansson, Swedish University of Agricultural Sciences
+4640415300, +46708793305