珊瑚礁

Jason deCaires Taylor casts giant cement sculptures that weigh thousands of pounds — and then sinks them into the ocean. His idea: to create a unique underwater gallery that algae, corals and other sea creatures can call home.

Each year in September, corals in the Caribbean stage a mass spawning event. Witnessing it, says marine biologist and TED Fellow Kristen Marhaver, is like swimming inside a snow globe. Here, she explains how corals beget corals — and how she and her fellow scientists are trying to help them along.