Pilot and Beaked Whales off the Canary Islands

A short-finned pilot whale (Globicephala macrorhynchus) surfaces explosively after its rapid dive, trailing a 4-foot-long squid tentacle from its mouth. The tentacle's length indicates that the whale is catching very large, deep-living squid. (Pablo Aspas)

During their field work off the Canary Islands, researchers on the newly published study found tentacles of giant squids (Architeuthis) floating in the water where pilot whales surface — tantalizing evidence of what the whales are hunting at depth. (Francisca Diáz, University of La Laguna)

Lined up for a nap: Pilot whales are social animals that lie in groups at the surface during daytime. They seem calm and untroubled by boat traffic, but actually they may be too exhausted from their strenuous dives to move when approached. (Francisca Diáz)

A trio of pilot whales underway at the surface, off the island of Tenerife, Canary Islands. Beneath the surface on a feeding dive, they make downward sprints of up to 20 miles per hour, remarkable speeds that consume up to 64 times more energy than a normal swim. (Nick Tregenza)

Short-finned pilot whales are small toothed whales found around the world. They are about 4 to 6 meters (13 to 20 feet) long, with a large rounded head that distinguishes them from other small toothed whale species. Though the whales are often visible at the surface, scientists don't know how many exist in the world. They believe that small local populations of the whales are threatened by human activity. (Frants Jensen, Aarhus University, Denmark)

A rare photo of a mother pilot whale and her calf, breaking the surface off Tenerife. Small populations of these whales live year-round in the very deep waters between the Canary Islands. (Teo Lucas, Balfin)

Blainville's beaked whales are similar in length to pilot whales and share the same deep waters off the Canary Islands. But they have a different lifestyle. They are the deepest divers of all known whales, making hour-and-a-half dives to a mile down &mdash on one breath. (Victor Gonzalez Otaola, University of La Laguna)

A rare Cuvier's beaked whale leaps near the island of El Hierro, Canary Islands. Here the seafloor drops off into very deep canyons where all three species of small toothed whales hunt squid. Using a different hunting style, sprinting pilot whales live in the same area as the slower-diving beaked whales, just as cheetahs carve out a niche in a habitat where other big cats hunt. (Natacha Aguilar de Soto, University of La Laguna )

The third little-known whale tagged and studied by the research team, Cuvier's beaked whales (Ziphius cavirostris) also shares deep water off the Canary Islands. Like other beaked whales, they are mysterious, extremely deep-and-long-diving whales that spend only about 8 percent of their time at the surface. (Marta Guerra, University of La Laguna)

Beaked whales are mysterious, seldom-seen animals. Because they dive slowly, 1 to 2 meters a second (2.2 to 5 miles per hour), they are able to conserve their breath and surface infrequently—but sometimes dramatically. (Iván Dominguez, University of La Laguna)