How Do They Get All This Energy?

Coral polyps stay in their home, the limestone cup they’ve built, a calyx, throughout their entire lives.

They can’t hunt for food, and have to rely on what comes to them.

How do they get enough food to reproduce, secrete skeletons, and build reefs that are the most ecologically productive and diverse ecosystems in the world?

It’s not from the tiny plankton and fish they are able to pull into their mouths, it’s from the algae.

The special algae that makes all the magic happen…

the zooxanthellae.

Zooxanthellae

Zooxanthellae are photosynthetic algae that live within the tissues of coral polyps.

They provide coral polyps with 90% of their energy through photosynthesis, and give the polyps their color.

(Polyps are naturally translucent)

Zooxanthellae and coral polyps have a mutualistic relationship: they rely on each other for survival.

Coral Polyps

provide the algae with a protected environment, and the compounds needed for photosynthesis: sunlight, carbon dioxide, and water.

That’s why you so often see reefs in shallow waters, more exposed to the energy of the sun’s rays. The algae needs the sunlight to photosynthesize, and provide the energy the coral needs for growth and survival.

Zooxanthellae

Through photosynthesis, zooxanthellae produce the proteins, fats, and carbohydrates needed for the corals to produce calcium carbonate — to secrete their limestone skeletons to build the reefs.

The energy zooxanthellae are able to produce via photosynthesis provides 90% of the corals’ food source

making them essential to sustaining corals’ life, and their growth.