Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New study involving CU-Boulder tells the tale of a kangaroo's tail

02.07.2014

Researchers find when a kangaroo is walking, it uses its tail just like a leg

Kangaroos may be nature's best hoppers. But when they are grazing on all fours, which is most of the time, their tail becomes a powerful fifth leg, says a new study.


This video is an analysis of video of kangaroos walking has helped scientists discover how important their tails are during locomotion.

Credit: Maxwell Donelan, Simon Fraser University

Involving researchers at the University of Colorado Boulder, Simon Fraser University in Burnaby, Canada, and the University of New South Wales in Sydney, Australia, the study illuminates the seemingly mundane task of foraging by red kangaroos. While such activity appears awkward, it turns out their tails provide as much propulsive force as their front and hind legs combined as they eat their way across the landscape.

"We found that when a kangaroo is walking, it uses its tail just like a leg," said Associate Professor Maxwell Donelan of Simon Fraser University, corresponding author for the study. "They use it to support, propel and power their motion. In fact, they perform as much mechanical work with their tails as we do with one of our legs."

... more about:
»Australia »Biology »kangaroos »study

"We went into this thinking the tail was primarily used like a strut, a balancing pole, or a one-legged milking stool," said Associate Professor Rodger Kram of CU-Boulder's Department of Integrative Physiology, a study co-author. "What we didn't expect to find was how much power the tails of the kangaroos were producing. It was pretty darn surprising."

Red kangaroos are the largest of the kangaroo species in Australia. When grazing on grasses, they move both hind feet forward "paired limb" style while using their tails and front limbs together to support their bodies. "They appear to be awkward and ungainly walkers when one watches them moseying around in their mobs looking for something to eat," said Kram. "But it turns out it is not really that awkward, just weird."

In human locomotion, the back foot acts as the gas pedal and the front foot acts as a brake, which is not especially efficient, said Kram. But he likens a walking kangaroo to a skateboarder who has one foot on the board and uses the other foot -- in this case a tail -- to push backward off the pavement, increasing the forward motion.

A paper on the subject was published online today in Biology Letters. In addition to Kram and Donelan, the paper was co-authored by Postdoctoral Fellow Shawn O'Connor of Simon Fraser and Emeritus Professor Terence Dawson of the University of New South Wales. The study was funded by the Natural Sciences and Engineering Research Council of Canada, the Australian Research Council, and traveling fellowships from the International Society for Biomechanics and the Journal of Experimental Biology.

Donelan, a former graduate student under Kram, said no animal other than the kangaroo uses its tail like a leg. "Their tails have more than 20 vertebrae, taking on the role of our foot, calf, and thigh bones."

The research project had its beginnings in 1973, when Dawson, a visiting professor at Harvard University, was working with Harvard Professor Richard Taylor, who later became Kram's advisor. Dawson coaxed a small group of kangaroos to hop and walk on a large motorized treadmill, with a goal of measuring the energy costs of locomotion at varying speeds. Dawson and Kram eventually showed that a kangaroo can increase its metabolism by 50 times during exercise.

"Kangaroos are really special mammals," said Dawson. "Work over the past half century has turned the notion that they belong to an inefficient, primitive group of mammals totally on its head."

The kangaroo tail also acts as a dynamic, springy counterbalance during hopping and boosts balance when male kangaroos grab each other by the chests or shoulders, then rear back and kick each other in the stomach in an attempt to assert dominance for the purpose of reproduction.

For the study the team videotaped five red kangaroos in Dawson's Sydney lab that had been trained to walk forward on a force-measuring platform with Plexiglas sides. The platform's sensors measured vertical, backward and forward forces from the legs and tails of the animals. The kangaroos had been taught that walking forward on the platform resulted in being rewarded with sweet treats, said Kram.

Over his career Kram and his students have studied the locomotion of a number of creatures, from elephants, tortoises and llamas to ostriches and beetles.

Although much of the data for the new study was collected years ago, other research efforts by the team members slowly pushed some of the key kangaroo locomotion data to the back burner. "But this was a study we just could not let go of," said Kram. "It was just too much fun. It's a real wonder of nature, how these kangaroos move about and what they are able to do."

Kram calls the evolution of the kangaroo tail, which is thought to have been prehensile when opossum-like kangaroo ancestors were living in trees, an "exaptation" -- a shift in the function of a biological trait over time. He likened it to a roll of duct tape in the back of a truck. "You know you are going to use it, you just don't know when," he said.

"I'm envious of kangaroos," said Kram, a competitive master runner in the mile and 1,500 meters. "When they hop faster, they don't use energy at a faster rate. The have the ability to move faster and not get tired, the ultimate goal of a runner."

Rodger Kram | Eurek Alert!
Further information:
http://www.colorado.edu

Further reports about: Australia Biology kangaroos study

More articles from Life Sciences:

nachricht Colorectal cancer risk factors decrypted
13.07.2018 | Max-Planck-Institut für Stoffwechselforschung

nachricht Algae Have Land Genes
13.07.2018 | Julius-Maximilians-Universität Würzburg

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Research finds new molecular structures in boron-based nanoclusters

13.07.2018 | Materials Sciences

Algae Have Land Genes

13.07.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>