Green-spotted fish walk along the bottom, their iridescent fins flashing. The next day, six researchers loaded their dive gear into a small boat and motored to Tennessee Reef, just off the southern coast of Long Key, to explore the lush coral reef. Coral reefs are some of the most biologically productive, complex and diverse ecosystems on Earth. The animals that form the foundation of these habitats are the corals themselves. These tiny animals make their homes atop the calcareous skeletons of their ancestors in clear, tropical waters.
Sponges are among the many splashes of color on coral reefs.
Multicolored sponges and algae, sea fans, shellfish and countless other animals build on top of the builders, colonizing the structures that successive generations of corals create. The spectacular reefs are as fragile as they are beautiful. The Johnson Sea Link submersible allows researchers to be as meticulous in the depths as the scuba divers are in the shallows. The robotic arm of the sub is virtually as precise as the fingers of a scientist. Before the availability of tools like the Johnson Sea Link, scientific trawls were one of the few techniques available for retrieving samples from the ocean bottom.