Scales of detection and escape of the sea urchin Tetrapygus niger in interactions with the predatory sun star Heliaster helianthus

► We assessed the spatial scales of escape and predator detection in Tetrapygus niger. ► Detection occurs through perception of chemical cues released by a predator seastar. ► Both detection and escape occurs within a spatial scale of about 50 cm. ► Non-lethal predator effects through T. niger behavioral modifications should be important at local spatial scales.