Early developmental stages of sea urchins are more sensitive to thermal stress than are adults, gametes or larvae. It’s a common assumption that developmental stages are more sensitive to stress than are adults, but this assumption is not tested often. We studied different life stages of the sea urchin Lytechius variegatus to test this assumption. We found that fertilization occurred and adults survived at temperatures higher than those ever experienced in the field but that early developmental stages are more sensitive and may experience stressful or lethal conditions during some times of the year. For more details read Collin and Chan (2016).