须鲸身体中发现新感觉器官

Scientists at the University of British Columbia and the Smithsonian Institution have discovered a sensory¹ organ in rorqual（须鲸科） whales that coordinates³ its signature lunge-feeding behaviour -- and may help explain their enormous size. Rorquals are a subgroup of baleen⁴ whales -- including blue, fin⁵, minke and humpback whales. They are characterized by a special, accordion-like blubber layer that goes from the snout to the navel. The blubber expands up to several times its resting length to allow the whales to engulf⁶ large quantities of prey⁷-laden water, which is then expelled through the baleen（鲸须） to filter krill and fish. #

The study, to be featured on the cover of the journal Nature, details the discovery of an organ at the tip of the whale's chin, lodged⁸ in the ligamentous（韧带的） tissue that connects their two jaws⁹. #

Samples were collected from recently deceased fin and minke whale carcasses captured as part of Icelandic commercial whaling operations. Commercial whaling in Iceland resumed in 2006 and quotas¹⁰ are determined¹¹ annually¹² by its government. #

Scanning of the whale's chin revealed a grape fruit-sized sensory organ, located between the tips of the jaws, and supplied by neurovascular（神经与血管的） tissue.

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The research team was assisted by technicians at FPInnovations, the owner of Canada's only X-ray computed¹³ tomography (XRCT) machine large enough to accommodate the massive specimens¹⁴. Used to scan giant logs, the XRCT machine provides a three dimensional map of the internal structure of whale tissues. #

"We think this sensory organ sends information to the brain in order to coordinate² the complex mechanism¹⁵ of lunge-feeding, which involves rotating the jaws, inverting¹⁶ the tongue and expanding the throat pleats and blubber layer," says lead author Nick Pyenson, a paleobiologist at the Smithsonian Institution, who conducted the study while a postdoctoral fellow at UBC. "It probably helps rorquals feel prey density¹⁷ when initiating¹⁸ a lunge." #

A fin whale, the second longest whale on the planet, can engulf as much as 80 cubic metres of water and prey -- equal or greater than the size of the whale itself -- in each gulp¹⁹ in less than six seconds. A previous study by co-author Jeremy Goldbogen showed that a fin whale captures 10 kilograms of krill in each gulp in order to sustain its average 50-ton body mass. Goldbogen, who conducted both studies while a PhD student at UBC, is now a scientist with the Cascadia Research Collective in Olympia, Washington.#p#分页标题#e#

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