Novel observation of an agonistic threat display by the nursehound Scyliorhinus stellaris Linnaeus 1758 towards a human snorkeller in Cornwall, UK

Elasmobranch fishes interact with humans through a diverse repertoire of behavioural responses, some of which have previously been described as agonistic or threat‐related displays. Although such behaviours are most often reported in species perceived as potentially dangerous to humans, responses to human approach remain poorly documented across many taxa considered largely non‐aggressive. Here, we describe a novel observation of a threat‐like display performed in response to an approaching snorkeller by a benthic elasmobranch species typically regarded as low‐risk to humans. We identify key behavioural features of the display and explore potential proximate triggers, including spatial context and approach dynamics. This observation contributes to a growing body of evidence that elasmobranch responses to humans are context‐dependent and may vary among individuals. More broadly, our findings support the concept of the “anti‐predatory response” within elasmobranchs and highlight the importance of documenting subtle behavioural interactions across a wider range of shark species. The behaviour observed here suggests that individual‐level variation and behavioural plasticity may play a greater role in human–elasmobranch encounters than previously assumed.