Navigation Links
How the octopus forms an elbow

The octopus arm is extremely flexible. Thanks to this flexibility--the arm is said to possess a virtually infinite number of "degrees of freedom"--the octopus is able to generate a vast repertoire of movements that is unmatched by the human arm. Nonetheless, despite the huge evolutionary gap and morphological differences between the octopus and vertebrates, the octopus arm acts much like a three-jointed vertebrate limb when the octopus performs precise point-to-point movements. Researchers have now illuminated how octopus arms are able to form joint-like structures, and how the movements of these joints are controlled.

The new findings, which appear in the April 18th issue of Current Biology, are reported by Tamar Flash of the Weizmann Institute of Science, Binyamin Hochner and German Sumbre of Hebrew University, and Graziano Fiorito of the Stazione Zoologica di Napoli.

The extreme motility of the octopus arm demands a highly complex motor control system. Past work from Dr. Hochner's group showed that when retrieving food to its mouth, the octopus actually shapes its arm into a quasi-articulated structure by forming three bends that act like skeletal joints. This puts an artificial constraint of sorts on the arm's movement and simplifies the otherwise complex control of movement that would be needed for the arm to fetch food from a distant point to the octopus's mouth.

In the new work, the researchers sought to identify how the octopus manages to transform its extremely flexible arm into a structure that acts like a jointed appendage. By recording muscle activity as the arm creates the joint-like bends, the researchers found that the arm generates two waves of muscle contraction that propagate toward each other, setting the second, or medial, joint at their collision point. This is a remarkably simple mechanism for adjusting the length of the arm segments according to where the object is grasped along the arm. The arm also forms a proximal joi nt near where the arm meets the body, and a distal joint near the suckers that have grasped the food. The medial joint typically exhibits the most movement during food retrieval.

The authors also found evidence that, like certain types of human arm movements, octopus fetching movements are controlled in terms of joint angles, rather than by a system that relies on the brain's coordinate-based map of external space.

The presence of similar structural features and control strategies in articulated limbs (for example, jointed vertebrate arms) and flexible octopus arms suggests that these qualities have evolved convergently in octopuses and in vertebrates, and it also suggests that an articulated limb--controlled at the level of joints--is the optimal solution to the challenge of achieving precise point-to-point movements by a limb.


'"/>

Source:Cell Press


Related biology news :

1. Products containing specific probes for detecting alternative splice forms protected
2. IBM Transforms the Art of Scientific Expeditions
3. MIT researcher presents new view of how the cortex forms
4. Carnegie Mellon U. transforms DNA microarrays with standard Internet communications tool
5. New study explores beetle species with two forms of females
6. AIDS-related cognitive impairment exists in two separate forms
7. Creating new life forms that may help eradicate cancer affecting women
8. Scientists discover new life forms in the Arctic Ocean
9. Genetic pathways to curable and incurable forms of pancreatic cancer identified
Post Your Comments:
*Name:
*Comment:
*Email:


(Date:2/7/2017)... 7, 2017 Zimmer Biomet Holdings, Inc. (NYSE ... will present at the LEERINK Partners 6th Annual Global ... on Wednesday, February 15, 2017 at 10 a.m. Eastern ... presentation can be accessed at http://wsw.com/webcast/leerink28/zbh .  The ... via Zimmer Biomet,s Investor Relations website at http://investor.zimmerbiomet.com ...
(Date:2/2/2017)... , Feb. 2, 2017   TapImmune, Inc. ... immuno-oncology company specializing in the development of innovative ... treatment of cancer and metastatic disease, announced today ... GMP manufacturing of a second clinical lot of ... folate receptor alpha. The manufactured vaccine product will ...
(Date:1/30/2017)... Jan. 30, 2017   Invitae Corporation (NYSE: ... genetic information companies, today announced that it will report ... provide 2017 guidance on Monday, February 13, 2017, and ... day at 4:45 p.m. Eastern / 1:45 p.m. Pacific. ... will briefly review financial results, guidance, and recent developments ...
Breaking Biology News(10 mins):
(Date:2/23/2017)... SAN JOSE, Calif. , Feb. 23, 2017 ... an exclusive license for two key immunotherapy technologies ... The first technology provides a method to monitor ... therapy such as PD-L1 and CTLA-4.  The second ... detect if a patient is likely to have ...
(Date:2/23/2017)... Antonio, TX (PRWEB) , ... February 23, 2017 ... ... Drug Administration (FDA) de novo clearance to begin marketing the SPEAC® System, the ... indicated for adults at home or in healthcare facilities during periods of rest. ...
(Date:2/23/2017)... ... 2017 , ... The Greater Gift Initiative, Inc , (GGI) a Winston-Salem, ... . GGI's mission is to advance global health and highlight the greater good of ... of each clinical trial volunteer. The vision of GGI is to serve as a ...
(Date:2/23/2017)... ... February 22, 2017 , ... ... , have been named Fellows of the Society this year, the Fellows Committee ... the multidisciplinary fields of optics, photonics, and imaging as well as their service ...
Breaking Biology Technology: