Fluorescence is not only widespread among reef fish and cnidarians – Cryptochiridae crabs also frequently emit an orange glow (see photo). This was discovered by a German-Dutch-Arab research team who photographed the coral-dwelling crabs in the Red Sea and off the Maldives, and examined collected specimens under a fluorescence microscope (Proceedings of the Royal Society B, 12 March). Orange fluorescence was found in nine of the fourteen genera studied, in four ‘fluorescence types’ with distinct patterns. These are thought to be linked to differences in habitat; the pattern may serve a camouflaging function.