Octopuses Have Favorite Arms They Use to Grab Different Prey

It can be difficult to keep two arms and two legs together. The arms of the octopuses are as if they have a mind of their own.

Motor control may be simplified if you stick to a preferred arm.

Researchers tested the response of the invertebrates to crustaceans dropped into their tanks. One eye could see the hidden octopuses. The video clips show how the octopuses used their second arm to catch their prey. The neighboring arms were used when needed.

"Although the eight arms are considered equipotential, such arm use for specific actions could reflect subtle evolutionary adaptation," the researchers wrote in their paper.

octopuses use different attack methods for crab and shrimp because they move at different speeds. The second arm was used to lead a pouncing, cat-like movement for crabs.

The faster and more evasive shrimps led more slowly with the second arm, which may have been used to camouflage the arm's movement.

The researchers theorize that the octopus sways its arms near the shrimp to avoid the shrimp's antenna and sensory hairs.

The neighboring arms were used to secure the helpless prey.

The researchers say that the consistency of the second arm attack is likely due to the field of vision of the octopus.

"As each eye of the octopus covers about 180 degrees with virtually zero intersection and displays limited eye movement and no head movement, it is likely that they prefer to place the target in the middle rather than at the border of their visual field."

When it comes to catching food in the wild, time is of the essence, and it seems as though using multiple arms can maximize the chances of getting food.

Biologists want to understand how neuron activity is linked to motor movements. The scientists don't think the central nervous system of the octopus is involved in recruiting additional arms to capture prey.

Researchers say that having a better understanding of the mechanics behind arm coordination could help in the development of soft robot that are going to work underwater.

The author of the study says thatOctopuses are strong. It's trivial for them to open a door.

We can apply that to make an underwater vehicle or soft robot.

The research has appeared in a journal.