Coral bleaching occurs when rising ocean temperatures stress corals into expelling the symbiotic algae (zooxanthellae) living in their tissue — the same algae that photosynthesize food for the coral and give it its vivid color. Stripped of its algae, the coral's white limestone skeleton shows through, and if the heat stress lasts too long the coral can starve and die. Bleaching events are becoming more frequent and severe worldwide as climate change drives marine heatwaves. In this simulation, watch the branching coral clusters shift from saturated pinks, oranges and blues toward a uniform bleached white as the timeline advances, then recover as conditions cool — use the controls to see how warmer water accelerates the transition.
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