Decoding deception: the binding affinity of cuttlefish ink on shark smell receptors.

Chemical signaling can play a crucial role in predator-prey dynamics. Here, we present evidence that ink from the common cuttlefish (Sepia officinalis) targets olfactory receptor proteins in sharks, potentially acting as a predator deterrent. We apply in silico 3D docking analysis to investigate the binding affinity of various odorant molecules to shark olfactory receptors of 2 shark species: cloudy catshark (Scyliorhinus torazame) and white shark (Carcharodon carcharias). Pavoninin-4 (a known shark repellent compound) displayed selectivity in binding to receptors in the white shark. In contrast, the primary component of cuttlefish ink, melanin, displayed the highest binding affinities to all shark olfactory receptor proteins in both species. Taurine, another important ink component, exhibited standard to strong bindings for both species. Trans-4,5-epoxy-(E)-2-decenal ("blood decenal"), an odorant associated with the smell of blood, displayed strong binding affinities to all shark olfactory receptors, similar to that of melanin. These findings provide new insights into the molecular interplay between cephalopod inking behavior and their shark predators, with cuttlefish ink likely exploiting the narrow band of the shark olfactory repertoire.