Whales are ‘cheetahs of the deep’

Super-fast pilot whales have been observed sprinting after prey, likely to include giant squid.

The rapid pursuit has brought comparisons with the fleet-footed land predator, the cheetah.

The cetaceans even use the same, highly specialised hunting strategy that cheetahs use, scientists report in the Journal of Animal Ecology.

They say it gives the lie to our perception that deep sea whales are slow, energy-saving creatures.

It is the first time such remarkable behaviour – occurring hundreds of metres underwater, in complete darkness – has been recorded.

“As far as we know, no other whale has been recorded to swim nearly as fast at depth,” says marine biologist Natacha Aguilar Soto, of La Laguna University in Tenerife, Spain.

“Short-finned pilot whales seem to be the greatest burst-speed athletes of the deep-diving mammals.”

Energetic sprint

Aguilar Soto is a member of an international team of researchers drawn from La Laguna University, Woods Hole Oceanographic Institution in Massachusetts, US, and Aarhus University, Denmark.

The team tagged and studied 23 short-finned pilot whales (Globicephala macrorhynchus) living off the coast of the Canary Islands, one of only three places in the world that these whales permanently reside.

The tags, designed by co-author Mark Johnson of Woods Hole, recorded the speed, depth and direction of the whales’ dives, and also the sounds made and heard by the whales.

During the day, the whales are frequently seen lazing on the surface, often in social groups (see video). That led scientists to previously think the whales only hunt at night. But the tags demonstrate the whales also hunt during the day. And when they do, they dive deep, and they dive fast.

Tags showed the whales take just 15 minutes to dive to depths of 800m to 1,000m (0.6 mile), and more.

And when they pinpoint their prey, the whales surge after it, reaching speeds of nine metres per second, or 32 kilometres per hour (20mph).

What’s more, they may keep up the sprint for 200m (650ft), before either catching the prey or giving up the chase.

The discovery fundamentally challenges our perceptions of how deep-sea creatures behave, says Aguilar Soto.

Until now, researchers assumed that deep-diving whales moved relatively slowly, due to the need to conserve oxygen whilst holding their breath.

“It was completely unexpected that short-finned pilot whales sprint at depth with limited oxygen reserves. Cheetahs, for example, more than double their breathing rate during chases,” says Aguilar Soto.

So like cheetahs, pilot whales must therefore follow a high-risk, high-gain hunting strategy based on high-speed, energetically expensive sprints. But somehow, the whales do it while still holding their breath. And that may explain why they are spotted lazing on the surface – the whales may be actually recovering from the exertion of the hunt.