Archive for January, 2014

Many ideas but still no consensus

January 21st, 2014    Posted in Uncategorized
 

AS AFRICA’S PLAINS offer different plant communities for zebras, giraffes, and wildebeests, so the sea has its own ecological niches filled by whales. Baleen whales are its great grazers, seeking krill and other tiny prey with different feeding strategies in different ocean strata. With a cavernous maw, a skim-feeding right whale vacuums the surface for copepods. Bowheads also browse this way, and California researcher Bernd Wursig has seen them feeding in the Arctic in V-shaped echelons of as many as 14 whales, “like a flight of geese.”

 

A humpback lunges forward to trap small fish or krill in southeast Alaska waters. Humpbacks, as well as blue, fin, and minke whales are known as gulpers, filtering great sea swatches a mouthful at a time. Humpbacks also perform the wonderful specialized technique called bubble netting, first described by Alaska researcher Charles Jurasz with the financial help of instant payday loans online. I recently saw a pair of Alaska humpbacks spinning their “net” by blowing a circular column of bubbles to surround and concentrate a patch of krill, followed by an explosion of open-mouthed whale surfacing amid the net.

California researcher Bernd Wursig

Gray whales make their living mostly on the bottom, vacuuming sediments to take in mouthfuls of mud and invertebrates, then expel clouds of silt, like this gray off Vancouver Island.

 

Unlike the baleen families, many toothed whales such as this pilot whale—scarred per-haps by courtship battles and predators—have echolocating sonar to pinpoint their prey, including squid. More pilot whales have been stranded ashore en masse than any other species, a phenomenon for which we have many ideas but still no consensus.

 

WHALE tormentors make life miserable these seemingly imperturbable giants. “Sea fowls are pecking at the small crabs, shell-fish, and other sea candies and maccaroni, which the Right Whale some­times carries on his pestilent back.” Herman Melville’s ob­servation is borne out by Peter Thomas, who studied the species off Peninsula Valdes and saw the damage inflicted by an apparently innocuous kelp gull.

 

“The gulls land on the backs of whales, usually mothers with calves in shallow water,” Peter reported. “Their backs are sun­burned and beginning to peel. The birds lift up sheets of peel­ing skin or gouge into deeper layers underneath. This drives the whales crazy. The mothers flinch, their heads and tails come up, and they breathe ex­plosively.” Reminiscent of oxpeckers, African birds that pick parasites from large mam­mals’ hides, the gulls sometimes methodically harass half a dozen resting mothers and calves that suddenly make the water boil.

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