Most people encounter corals as branching husks, washed ashore, or as brilliantly colored backdrops underwater. However vibrant those impressions may be, they're static. But corals are animals, rooted to the ocean floor but capable of some hypnotically beautiful movement, as this time lapse video by PhD student Daniel Stoupin shows.
By day most hard corals are cute and colorful...Their polyps coexist with their symbiotic algae and depend on light for nutrients produced by their photosynthetic symbionts. By night these polyps open up like flowers, but unlike flowers they turn into fierce predators, extend their tentacles, and sometimes invert their guts to digest the crap out of everything that they can reach. Coral colonies have to compete for substrate with other species, sometimes in violent battles. The winner is usually the species who digests faster or can resist digestive enzymes of the attackers better.
Stoupin's video is comprised of 150,000 images of gyrating, squirming, living corals—sit quiet for a minute and just watch them move.