Slide 1
An animal makes a reef
A coral polyp is a small animal with tentacles around a mouth. Many reef-building species live as connected colonies.
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Stony corals secrete calcium carbonate skeletons. Generations of growth, breakage and accumulation help make a reef, so a reef is more than the outline of one living colony.
Slide 2
Sharing a source of energy
Many shallow-water corals host microscopic algae in their tissues. The algae use sunlight and supply food to their animal hosts.
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The coral also catches prey with stinging cells. This combination helps explain how an animal can benefit from sunlight without becoming a plant or relying on only one feeding route.
Slide 3
A partnership under stress
Heat stress can cause corals to lose their partner algae. The pale skeleton becomes visible through the remaining coral tissue.
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Bleaching does not necessarily mean immediate death. If conditions improve, some corals recover their partners; prolonged or repeated stress can leave too little energy for survival and reproduction.
Slide 4
Reefs make room for others
Coral growth creates crevices, ledges and sheltered spaces. Fish and invertebrates use that structure for food, refuge and breeding.
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The living surface and the older skeleton serve different roles. Damage can therefore alter both the organisms present today and the physical habitat available to future reef residents.
Slide 5
Not every coral needs sunlight
Deep-sea corals can live beyond useful sunlight. These corals do not depend on the same light-powered partnership as shallow tropical reefs.
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Cold, dark coral habitats remind us that coral describes a broad group of animals. Conditions suitable for one community should not be treated as requirements for every coral.
Sources
- Corals and Coral Reefs
Smithsonian Ocean
- What is coral bleaching?
NOAA