Tropical cuttlefish a model organism to study travelling waves in biological systems
Some cephalopods are masters of display: Not only can they adapt their skin colour to their immediate environment, thereby merging with the background, they can also produce propagating colour waves along their body. These so-called 'passing clouds' can be observed in behavioural contexts such as hunting, swimming, mating, or even in animals resting under rocks. Their function, however, remains highly speculative. Researchers at the Max Planck Institute for Brain Research in Frankfurt, Germany, have identified a cuttlefish species in which these waves are so prevalent that their properties can be studied in the laboratory. Using simple behavioural methods, they have circumscribed their possible underlying causes to a relatively small set of neuronal circuits.