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A case of getting the Humpback's choreography worked out

By Dave Armstrong - 11 Oct 2012 11:20:47 GMT
A case of getting the Humpback's choreography worked out

David Ashley's epic pic of a humpback breaching seems to mirror the great singing ,dancing and energetic implied by this study from researchers at the Greenland Institute of Natural Resources, the Sea Mammal Research Unit at the University of St Andrews, Scotland, Aarhus University in Denmark and Woods Hole Oceanographic Institution, US - Humpback whale image; Credit: © Shutterstock

Large immovable objects have a habit of being limited, but Malene Simon, Mark Johnson and Peter Madsen (affiliations mentioned above) have solved one of the sea's great pondering problems. In the Journal of Experimental Biology, the submarine lifestyle of the whale has been uncovered by the use of data-logging tags, on both ends of the dorsal fin. Greenland now has 5 humpback whales (Megaptera novaeangliciae) who know what it is to be choreographed. And they probably sing about it, if you know your whales.

This whale works at great depth to catch krill, particularly the nimble capelin, by lunging at gigantic "gulps" of them as they swim away. This is also the whale that fishes with bubble nets. A speed of 2.0 m s-1 is achieved so that the krill can be corralled with the gaping mouth as well as the lower part of the buccal pouch. The size of that gape causes a massive amount of "drag" on the whale's progress through the water.

While momentum in the whale is impressive, it was previously believed that the beautiful beast came to a full stop after gulping. However, the timing of those wing-like fluke movements makes sure that the mass of engulfed water gets the momentum required to continue gliding at 1 to 1.5m s-1 (metres per second), after humpbacks have lunged at the prey. What happens next is a 46 second filter and handling operation in the buccal cavity, as the whale re-positions ready for the next lunge at the krill.

This all means that the lunge method of feeding could be less expensive in energy than was thought. It is tremendously demanding, despite these findings, as a total of 30 tons of water is held inside that mouth and buccal pouch. If you look down our main page, you'll find a full account of the humpback (and even David Attenborough) in our encyclopaedia section.

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Topics: Whales