Watch cuttlefish apparently pretending to walk just like crabs

31 May 2017


By Sandrine Ceurstemont

Cuttlefish have been caught on film walking like crabs by moving their tentacles in novel ways.

Kohei Okamoto at the University of the Ryukyus in Okinawa, Japan, and his team first spotted pharaoh cuttlefish (Sepia pharaonis) displaying the unusual behaviour while feeding them in the lab.

“We were surprised to see how closely they resemble hermit crabs,” says Okamoto.
  
The molluscs would raise their front arms while they bent their other legs, as if they had joints, while quickly moving them up and down independently. Certain parts of their skin also darkened.

The team later filmed the cuttlefish making the same arm movements during experiments in tanks containing small fish that could be prey (see video below).

Cuttlefish are known mimics. They can change colour, texture, skin patterns and even posture instantly to blend in with their surroundings. They can also make complex movements with their arms, not only to help with camouflage but also to startle or lure prey or grip their partner while mating.



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Homo erectus walked just like modern humans, study finds

JULY 14, 2016

by Brett Smith

Researchers have found our mysterious forbearer Homo erectus may have had the same gait as us, according to a press release form the Max Planck Institute in Germany.

Previous study has revealed Homo erectus, who lived from about 1.9 million years ago to 140,000 years ago, could be the first human predecessor to have the body of a modern human. The primate's long legs indicate it had adapted to bipedal locomotion along the ground, rather than climbing trees like an ape.

To learn more on the walking patterns of a species, scientists typically analyze an animal's feet, legs, and hips. However, a lack of Homo erectus fossils prevents a robust analysis. For instance, just one selection of foot bones, discovered at the Dmanisi site in the European country of Georgia, has been associated with Homo erectus. And even then, the taxonomy of the remains at Dmanisi has been disputed.

Examining Existing Homo erectus Tracks

In the new study, the scientists examined the eight best-preserved tracks from Homo erectus, and the footprints of modern people from the nearby Daasanach group, who spend their day walking barefoot. In many instances, the researchers discovered that these two groups of prints were "statistically indistinguishable," which might reflect comparable foot anatomies and motions.

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Borneo's Orangutans Are Coming Down from the Trees

July 29, 2013 — Orangutans might be the king of the swingers, but primatologists in Borneo have found that the great apes spend a surprising amount of time walking on the ground. The research, published in the American Journal of Primatology found that it is common for orangutans to come down from the trees to forage or to travel, a discovery which may have implications for conservation efforts.

An expedition led by Brent Loken from Simon Fraser University and Dr. Stephanie Spehar from the University of Wisconsin Oshkosh, travelled to the East Kalimantan region of Borneo. The region's Wehea Forest is a known biodiversity hotspot for primates, including the Bornean orangutan subspecies, Pongo pygmaeus morio, the least studied of orangutan subspecies.

"Orangutans are elusive and one reason why recorded evidence of orangutans on the ground is so rare is that the presence of observers inhibits this behaviour," said Loken. "However, with camera traps we are offered a behind the scenes glimpse at orangutan behaviour."

The team positioned ground-based cameras across a 38-square-kilometre region of the forest and succeeded in capturing the first evidence of orangutans regularly coming down from the trees. The amount of time orangutans spent on the forest floor was found to be comparable to the ground-dwelling pig-tailed macaque, Macaca nemestrina, which is equally abundant in Wehea Forest. Over 8-months orangutans were photographed 110 times, while the macaques were photographed 113 times.

Continued

Different Neuronal Groups Govern Right-Left Alternation When Walking

June 30, 2013 — Scientists at Karolinska Institutet in Sweden have identified the neuronal circuits in the spinal cord of mice that control the ability to produce the alternating movements of the legs during walking. The study, published in the journal Nature, demonstrates that two genetically-defined groups of nerve cells are in control of limb alternation at different speeds of locomotion, and thus that the animals' gait is disturbed when these cell populations are missing.

Most land animals can walk or run by alternating their left and right legs in different coordinated patterns. Some animals, such as rabbits, move both leg pairs simultaneously to obtain a hopping motion. In the present study, the researchers Adolfo Talpalar and Julien Bouvier together with professor Ole Kiehn and colleagues, have studied the spinal networks that control these movement patterns in mice. By using advanced genetic methods that allow the elimination of discrete groups of neurons from the spinal cord, they were able to remove a type of neurons characterized by the expression of the gene Dbx1.

"It was classically thought that only one group of nerve cells controls left right alternation," says Ole Kiehn who leads the laboratory behind the study at the Department of Neuroscience. "It was then very interesting to find that there are actually two specific neuronal populations involved, and on top of that that they each control different aspect of the limb coordination."

Read on: http://www.sciencedaily.com/releases/2013/06/130630145008.htm

Ancient walking gets weirder

The simple act of walking continues to take strange detours among ancient human ancestors. 


To wit, 1.5 million-year-old footprints excavated in Africa, initially thought to reflect a thoroughly modern walking style, were instead made by individuals that walked differently than people today do, researchers reported April 13 at the annual meeting of the American Association of Physical Anthropologists. 

And findings presented April 12 at the meeting revealed the surprisingly apelike qualities of foot fossils from a 2 million-year-old species that some researchers regard as the root of the Homo genus. 

These reports come on the heels of evidence that a previously unknown member of the human evolutionary family 3.4 million years ago possessed a gorillalike grasping big toe and an ungainly stride. 

Depth measurements of the African footprints, discovered at Kenya’s Ileret site, differ at 10 landmarks from the footprints of people who live in that area today, said graduate student Kevin Hatala of George Washington University in Washington, D.C. 


Continued:  http://archaeologynewsnetwork.blogspot.co.uk/2012/04/ancient-walking-gets-weirder.html?utm_source=feedburner&utm_medium=email&utm_campaign=Feed:+TheArchaeologyNewsNetwork+%28The+Archaeology+News+Network