Fascinating Research Shows Octopuses Prefer Certain Arms in Hunting

A new study reveals that octopuses have preferred arms in hunting their prey. The results are helpful for a bioinspired robot design.

Octopuses are famously known for having eight arms. It is an octopus' advantage against its prey. But unlike in the movies showing octopuses to use most arms, a study shows that they preferred arms in hunting.

What are octopuses first? According to National Geographic, they are cephalopods with squid and cuttlefish. Celepahods or head-foot have limbs attached to one's heads.

Amazingly, there are 300 species of octopuses recorded so far that are present in the ocean.

The size can reach 1/2 inches or 30 feet, and the weight is up to 600 pounds.

Despite the size, octopuses are intelligent animals that have mastered camouflaging to hunt for prey and evade attackers.
They are also agile with a soft body and capable of penetrating areas that are not smaller than their body.
Octopuses can regrow their arms lost in battles or attacks.
Octopuses' diet is mollusks, crabs, or shrimps.

National Geographic added that octopuses could find ways to open clamshells.

Research findings

(Photo by Robert Cianflone via Getty Images)

According to Trevor Wardill, who studies octopuses and cephalopods, it might be normal to look at an octopus in which nothing is repeatable. Wardill is also an assistant professor in the College of Biological Sciences.

As a result, he and his team studied whether octopuses preferred or used each arm equally in the hunting process. The study "Octopuses prefer certain arms when hunting and adjust tactics to prey" is also published in Science Daily.

Based on the reports, the researchers studied the California two-spot octopus living for about two years. They numbered arms on each side of the Octopus' body. The octopus size is said to be like tennis balls.

Also Read: Octopus Ancestors Among the First Animals on Earth, Dating Back to 509 Million Years Ago!

Different types of prey, namely crabs and shrimp, were dropped in the tank as the octopus hid with eyes looking upward. After the experiment, the researchers discovered:

The octopus was found using arms on the same side to eye-view the prey.
The prey the researchers dropped shows that each octopus attacked with the second arm from the middle.
In hunting crabs, the octopus quickly pounced on the prey with the second arm.
On the other hand, shrimp hunting reveals different cases. The octopuses were more careful to avoid disturbing the prey. The octopus used the second arm as it caught the target. Then, it used neighboring one and three arms to secure the food prey.

The findings were fascinating. The study's lead author, Flavie Bidel, explained that he was shocked at octopuses using the second arm. He said octopuses have unpredictable movements, but the hunting behavior was repeatable. He is also a postdoctoral researcher.

Bidel added that the next step is to research how the octopus' neurons influence arm movements.

Robot designs

The study findings are helpful for next-generations studies that develop highly manipulative soft robots such as underwater vehicles and soft robot applications that can help in deep ocean explorations, research says.