Consumptive and Non‐Consumptive Effects of Predators Vary with the Ontogeny of their Prey

We investigated how the effects of predators vary with the ontogeny of a key herbivorous sea urchin, which is responsible for transforming diverse macroalgal forests to a barren state dominated by bare rock and encrusting coralline algae. Predators mostly consumed smaller sea urchins. Unexpectedly, however, only larger sea urchins showed anti‐predator behaviors, significantly reducing their grazing activity. Crucially, only these larger sea urchins were capable of transforming macroalgal forests. The decoupling between risk and fear as prey growth indicates that the strength of consumptive and non‐consumptive trophic cascades may act differently at different ontogenetic stages of prey. This photograph illustrates the article “Consumptive and non‐consumptive effects of predators vary with the ontogeny of their prey” by Albert Pessarrodona, Jordi Boada, Jordi F. Pagès, Rohan Arthur, and Teresa Alcoverro published in Ecology. https://doi.org/10.1002/ecy.264