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• Corals are tiny animals. Living within their tissues they have numerous microscopic algae (dinoflagellates). While the corals have tentacles and can capture some food from the plankton, they are also highly reliant on these algae to provide them with extra food. The algae photosynthesise, and create sugars from sunlight. The corals provide shelter and other resources to the algae and the two organisms live in a tight relationship.
• Stresses such as high temperatures lead to the corals loosing these algae. The coral’s tissue becomes transparent and the underlying white skeleton is clearly seen.
• Temperatures only 1-2°C above the normal are sufficient to cause a coral to bleach within a few days
• At this stage the corals may still recover, re-establishing a partnership with new algae. If the cause of stress continues the corals loose condition and die.
• Within days the dead corals become overgrown with a dense hazy cover of fine green or brown algae.