krill and agile capelin.
Attaching individual tags behind the dorsal fin on three of the whales – to record their stroke patterns – and nearer the head in the remaining whales – to better measure head movements – the team successfully recorded high resolution depth, acceleration and magnetic orientation data from 479 dives to find out more about the animals' lunge tactics. Simon, from the Greenland Institute of Natural Resources, Madsen, from Aarhus University, Denmark and Johnsen from the University of St. Andrews, UK, report how whales choreograph their foraging lunges at depth in The Journal of Experimental Biology at http://jeb.biologists.org.
Analysing the whales' acceleration patterns, Simon saw that as the whales initiated a lunge, they accelerated upward, beating the tail fins (flukes) twice as fast as normal to reach speeds of 3m/s, which is not much greater than the whales' top cruise speeds. However, while the animals were still beating their flukes, the team saw their speed drop dramatically, although the whales never came to a complete standstill, continuing to glide at 1.5m/s even after they stopped beating their flukes. So, when did the whales throw their mouths open during this sequence?
Given that the top speed attained by the whales during the early stages of the lunge were similar to the animals' cruising speeds and the fact that the whales were beating their flukes much harder than usual to maintain the speed, the team conclude, 'The implication is that the mouth must already be open and the buccal [mouth] pouch inflated enough to create a higher drag when the high stroking rates… occur within lunges'. In addition, the team suggests that the whales continue accelerating after opening their mouths in order to use their peak speed to stretch the elastic ventral groove blubber that inflates as they engulf water. Once the buccal pouch is fully inflated, the whales continue beating their flukes after closing their mouths to accelerate the colossal quantity of water, before ceasing fluke movement and slowing to a new speed of 1.5m/s. Finally, the animals filter the water and swallow the entrapped fish over a 46s period before resuming beating their flukes as they launch the next lunge.
Considering that humpback whales and other rorquals were thought to grind to a halt after throwing their jaws wide and that reaccelerating their massive bodies from a stationary start was believed to make lunge feeding extortionately expensive, the team's discovery that the animals continue gliding after closing their mouths suggests that lunge feeding may be cheaper than previously thought. However, the team concedes that despite the potential reduction in energy expenditure, lunge feeding is still highly demanding – the whale must accelerate the 30 tons of water held in its mouth – although they suggest that the high-speed tactic is essential for the massive hunters to engulf their nimble prey.
IF REPORTING ON THIS STORY, PLEASE MENTION THE JOURNAL OF EXPERIMENTAL BIOLOGY AS THE SOURCE AND, IF REPORTING ONLINE, PLEASE CARRY A LINK TO: http://jeb.biologists.org/content/215/21/3786.abstract
REFERENCE: Simon, M., Johnson., M. and Madsen, P. T. (2012) Keeping momentum with a mouthful of water: behavior and kinematics of humpback whale lunge feeding. J. Exp. Biol. 215, 3786-3798.
This article is posted on this site to give advance access to other authorised media who may wish to report on this story. Full attribution is required, and if reporting online a link to jeb.biologists.com is also required. The story posted here is COPYRIGHTED. Therefore advance permission is required before any and every reproduction of each article in full. PLEASE CONTACT email@example.com
Kathryn Knight | EurekAlert!
A Map of the Cell’s Power Station
18.08.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau
On the way to developing a new active ingredient against chronic infections
18.08.2017 | Deutsches Zentrum für Infektionsforschung
Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.
As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...
Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.
Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...
For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.
While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...
An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.
The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...
A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.
Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...
16.08.2017 | Event News
04.08.2017 | Event News
26.07.2017 | Event News
18.08.2017 | Life Sciences
18.08.2017 | Physics and Astronomy
18.08.2017 | Materials Sciences