How the octopus forms an elbow( The octopus arm is extremely flexible. ...)

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 jo
'"/>

Contact: Heidi Hardman
hhardman@cell.com
617-397-2879
Cell Press
17-Apr-2006

Page: 1 2
Related biology news :

1. Toward improved forms of a time-tested cholesterol-fighter
2. Creating new life forms that may help eradicate cancer affecting women
3. Chromium picolinate shows greater benefits in diabetes care than other forms of chromium
4. Low-pathogenic forms of bird flu do cause illness among birds
5. National Science Foundation supports UCR study of polar lake life forms
6. Scientists discover new life forms in the Arctic Ocean
7. JDRF forms partnership with MacroGenics
8. The CReSA is working on a new strategy to combat spongiforms
9. Figuring out function from bacterias bewildering forms
10. Studies show that rockfish thrive with offshore platforms as their home base
11. UCSD forms stem cell collaboration with major Australian centers