
This colorful coral lives in Australia's Great Barrier Reef, which is rapidly shrinking due to human impacts.

A Caribbean hermit crab (Coenobita clypeatus) crawls on the forest floor.
Flickr user Island Conservation

When this tusk shell was brought up from a dive it was a surprise when a hermit crab poked out. The large claw that you see can be pulled in to cover the shell opening.
Barry Brown/Substation Curacao

The Autonomous Reef Monitoring Structure was developed to help scientists study coral reef diversity and have now been adopted broadly to study diversity around the world.
Laetitia Plaisance/CReefs, Census of Marine Life

The Curasub departs for a deep sea dive, up to 1,000 feet off the island of Curaçao, where this sub is located.
Trish Mace/ Smithsonian Institution

Where the pH is the lowest, corals can no longer grow - sand, rubble and seagrasses replace the reef.
Laetitia Plaisance

Dive through the zones of the ocean to the deep ocean bottom -- like this remote operated vehicle (ROV) -- where many strange species live, and there are many yet to be discovered. Explore them in the Deep Ocean Exploration section.

Corals, sponges and seaweeds cover most of the surface of many coral reefs.
Wolcott Henry

Scripps Institution of Oceanography's FLoating Instrument Platform, or FLIP, conducts sea trials off San Diego in May 2009.
© 2009 Scripps Institution of Oceanography

The Autonomous Reef Monitoring Structure was developed to help scientists study coral reef diversity and have now been adopted broadly to study diversity around the world.
Laetitia Plaisance/CReefs, Census of Marine Life
