Coral Polyp

The tiny animal that builds the largest living structures on Earth/Deep Sea & Ocean Life

A single coral polyp is a tiny soft-bodied animal typically just 1 to 3 millimeters in diameter, weighing about 1 milligram. Despite their minuscule size, colonies of coral polyps are responsible for building the largest biological structures on Earth -- the Great Barrier Reef stretches over 2,300 kilometers. Each polyp secretes calcium carbonate to form a hard skeleton, and over thousands of years these skeletons accumulate into massive reef structures. Coral polyps also maintain a symbiotic relationship with photosynthetic algae called zooxanthellae, which give corals their color and produce up to 90% of their energy. When stressed by heat, corals expel these algae and bleach white, which is as bad as it looks.