Join Defenders of  Wildlife board member Jeff Corwin as he continues to document how the Gulf oil disaster will impact wildlife in the region. In this Nightly News piece with MSNBC’s Brian Williams, Jeff dives right in to check on the health of the largest fish on the planet: the whale shark.

They may be large (growing up to 40 feet in length!), but whale sharks are gentle giants, feeding mostly on plankton filtered through their enormous mouths. Feeding at the base of the food chain, they are at great risk in a still oil-stricken Gulf. However, the sharks are also a great indicator species for the health of the entire Gulf ecosystem. By affixing tracking devices to their fins, researchers can follow the fish and the depth at which they swim.

“Now that this whale shark has been fitted with transmitters, we’ll now know if it’s coming into harm’s way.” Jeff explains from the water.