How Coral Reefs Work

2/9/2012, 1:52:57 PM , duration(0:0:2)
Society & Culture
Coral reefs are the largest organic structures on Earth, yet they're created through a symbiotic relationship between creatures about 3 millimeters long. Learn more about the the world's coral reefs (and how to protect them) in this episode.<br><br> Learn more about your ad-choices at <a href=''></a>