In addition to mantas, the Revillagigedos have other life. We saw numerous species of sharks, including silkies, Galapagos, silvertip, and scalloped hammerhead sharks (like this one). This species of hammerhead is schooling, and the presence of a few suggests schools of hundreds or thousands beyond view. Unfortunately, these and other species of sharks are being slaughtered by the the millions each year worldwide to satisfy the demand for shark-fin soup in Asia.
From Socorro - Nov 2010