Scientists at the University of British Columbia and the Smithsonian Institution have discovered a sensory organ in rorqual whales that coordinates its signature lunge-feeding behaviour and may help explain their enormous size.
Rorquals are a subgroup of baleen whales including blue, fin, 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 engulf large quantities of prey-laden water, which is then expelled through the baleen 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, lodged in the ligamentous tissue that connects their two jaws.
NB: Illustrations of lunge-feeding and the location of the sensory organ, photos of the researchers at work at the Icelandic whaling station and a comprehensive Frequently Asked Questions are available at http://nmnh.typepad.com/pyenson_lab/nature-rorquals-organ.html.
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 quotas are determined annually 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 tissue.
The research team was assisted by technicians at FPInnovations, the owner of Canada's only X-ray computed tomography (XRCT) machine large enough to accommodate the massive specimens. 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 coordinate the complex mechanism of lunge-feeding, which involves rotating the jaws, inver
|Contact: Heather Amos|
University of British Columbia