What swims at 20 mile per hour and can carve out hunks of human flesh? The Humboldt Squid.

Cassell first heard about the "diablos rojos," or red devils, in 1995, from some Mexican fishermen as he was filming gray whales for German public television in Baja's Laguna San Ignacio. Intrigued, he made his way to La Paz, near the southern tip of Baja, to dive under the squid-fishing fleet. It was baptism by tentacle. Humboldts—mostly five-footers—swarmed around him. As Cassell tells it, one attacked his camera, which smashed into his face, while another wrapped itself around his head and yanked hard on his right arm, dislocating his shoulder. A third bit into his chest, and as he tried to protect himself he was gang-dragged so quickly from 30 to 70 feet that he didn't have time to equalize properly, and his right eardrum ruptured. "I was in the water five minutes and I already had my first injury," Cassell recalls, shaking his head. "It was like being in a barroom brawl." Somehow he managed to push the squid-pile off and make his way to the surface, battered and exhilarated. "I was in love with the animal," he says.