Smart whales

To capture enough food for their enormous bodies, blue whales use an extreme technique called lunge feeding. They take enormous gulps of water, then let it pass through comb-like mouth filters called baleen, keeping krill behind for consumption.

And sometimes, a new study reports, they also do an acrobatic roll to help them capture krill more effectively. Writing in Biology Letters, researchers explain that the whales sometimes roll 180 degrees, so their backs face the seafloor as they accelerate and move forward to open their mouths for a lunge.

“They engulf from right beneath the krill patch so they are less likely to be seen,” said the study’s first author, Jeremy Goldbogen, a comparative physiologist at the Cascadia Research Collective in Olympia, Wash. “This minimises the escape of the krill. ”

The whales complete their roll, flipping over another 180 degrees, while filtering water through their mouths. “The whole process can be finished in about 20 to 30 seconds,” said Goldbogen.

That is pretty fast, considering that blue whales are the world’s largest animals. Goldbogen and his colleagues studied 22 whales living off the coast of Southern California. Only about half used the technique while they were being monitored, and those whales did it only about 10 per cent of the time.”

“They may be using it in very small krill patches as a way to minimise the krill escape response,” Goldbogen said. When there are dense patches of krill, the acrobatic manoeuvres may not be necessary. Goldbogen believes that other lunge feeders may use the technique as well. “We haven’t observed it yet,” he said, “but with more research and more tags we’re likely to find it in other closely related whales, like fin whales.”

Jumping crickets

Pygmy mole crickets are tiny insects that live in burrows near fresh water in warm places like Florida and South Africa. On land, they are expert jumpers, using the skill to escape the clutches of tiger beetles and other predators. Now, researchers report that these insects are also skilled at jumping from the surface of water.

They do this using a series of spring-loaded, oarlike paddles on their back legs, as reported in the journal Current Biology.

While animals like pond skater insects and fisher spiders balance on the water’s surface, pygmy mole crickets exploit the water’s viscosity. “They whack their legs onto the surface of water and actually penetrate the water,” said an author of the study, Malcolm Burrows, a zoologist at the University of Cambridge.

“They sort of grab the water, and as their legs enter, these little paddles flare out. ” The action pushes down water, setting off a reaction that pushes the insect upward and out of the water, Burrows said. The jump helps them escape from fish and predatory insects.

Burrows first noticed pygmy mole crickets while he was eating his lunch by the side of a pond in South Africa. He collected a few specimens and studied them in a laboratory, along with his colleague, Gregory Sutton, a researcher at the University of Bristol in England.

Sindya N Bhanoo                                   
New York Times News Service

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