SCIENCE NATURE SPECIAL : LAB

 

REACHING A CONCLUSION

The Sixth Sense That Octopuses Use To Keep Their Eight Arms Whole :

Though it is well known for its many arms, the octopus does not seem to know where those appendages are most of the time.

''In the octopus, yes you have no bones and no joints, and every point in its arm can go to every direction that you can think about,'' said Nir Nesher, a senior lecturer in marine sciences at the Ruppin Academic Center in Israel.

''So even one arm, it's something like endless degrees of freedom.'' So how does the octopus keep all those wiggly, sucker-covered limbs out of trouble? 

According to new study published last month by Dr. Nesher and his colleagues, the octopus's arms can sense and respond to light - even when the octopus cannot see it with the eyes on its head.

The light- sensing ability may help the cephalopods keep their arms concealed from other animals that could mistake the tip of an arm for a marine worm or some other kind of a meal.

This was a surprise, as though the octopus ''can see the light through the arm, it can feel the light through the arm,'' Dr. Nesher said. ''They don't need an eye for that.''

[Richard Sima]