Test your knowledge with these top questions!
What makes coral reefs so colorful in healthy conditions?
The algae are not just doing chores; they carry their own pigment colors, which shine through the coral's clear tissue.
Which ocean body contains Australia's Great Barrier Reef?
The Great Barrier Reef stretches across more than 2,300 kilometers of the Coral Sea off Queensland's coast.
Coral polyps build hard reef structures by secreting skeletons made of:
Stony corals extract calcium and carbonate ions from seawater to build protective limestone skeletons.
What causes coral bleaching?
When water gets too warm, corals eject their algae and turn ghostly white—it is a stress response, like a fever.
How do corals get most of their energy?
Those algae are tiny solar panels; they use sunlight to make sugars and pass most of them to the coral.
Coral bleaching occurs primarily when polyps expel their symbiotic algae due to:
Thermal stress causes corals to expel zooxanthellae, turning the reef stark white and starving the host polyps.
What do coral reefs provide for about 25% of all marine species?
One in four marine species finds a home among corals, yet the reefs themselves cover less than 1% of the ocean floor.
Coral polyps share a symbiotic relationship that provides most of their food with:
Zooxanthellae live inside coral tissues and photosynthesize, providing up to 90 percent of the host polyp's energy.