Corals Spin Tiny Vortices to Get Oxygen, but Not if It’s Too Hot

At first glance, corals present as little more than colorful rocks — piles of lobes, stalagmites, and branches poking out from the seafloor. They are anything but. Corals are complex creatures that form enduring colonies, and just like other animals they need oxygen to live. Across the living surface of coral, a frantic dance of survival takes place, invisible to our eyes and unknown to science… Source