They will squeeze through any crack. Scientists discover the secret of octopuses

Flexible bodies without a skeleton

Octopuses are creatures without a rigid skeleton, which makes them extremely flexible. Their body is built around the so-called muscular hydrostats - a system of muscles that provide support and enable movement without the involvement of bones. The octopus's eight arms can bend, extend and curve in almost any way, and the central part of its body, called the pouch, can change its shape as needed.

The circulatory system of these animals is also adapted to such great flexibility. Major blood vessels have muscular pumping systems that keep blood circulating even when parts of the body are tightly compressed.

The sequence of movements is the key to success

The latest research, conducted by an international team of scientists, allowed to map the exact sequence of octopus movements when squeezing through holes of different widths.

In the wild, octopuses have the ability to move through spaces smaller than their own bodies, a skill called squeezing behavior, explains Wenci Xin, a researcher at the Soft Robotics Lab at the National University of Singapore.

Scientists conducted experiments on three juvenile common octopuses. The animals had to cross an opening of adjustable width, and their movements were precisely recorded on video. Analysis of the recordings allowed us to identify two main patterns of action: three-stage and four-stage.

Two squeezing patterns

If the hole was wider than the distance between the octopus's eyes, the animal used a three-step process: first it explored the hole with one arm, then it pulled several more through it, and then it used the already inserted arms to pull the rest of its body up. In the case of a narrower opening, an additional stage appeared - the octopus first dragged its remaining arms, and only then its head and body bag.

At first, we expected the animals to use the same strategy... We were surprised when it turned out to change, admits Xin.

It's not entirely clear what ultimately limits the octopus's squeezing abilities. Until now, it was believed that the beak, the only stiff part of the body, played a decisive role. However, recent experiments suggest that it may be more about the size of the shoulders at the base of the body.

Inspiration for robotics

Squeezing through narrow gaps is not only a biological curiosity - it is an important survival skill for octopuses. It allows them to escape from predators and get to places where other creatures cannot access, and thus obtain food.

Research into the flexibility and movement of octopuses may have implications not only for biology, but also for engineering. Scientists hope that understanding these mechanisms will allow the development of new types of robots capable of working in hard-to-reach places, e.g. during rescue operations.

As Xin points out, currently designed rescue robots are usually long and slender to fit through narrow gaps. However, octopus inspiration could allow the creation of machines with flexible arms, capable not only of squeezing through tight spaces, but also of carrying tools, sensors and communication devices.

However, building such a robot is a big challenge. The arms would have to be both soft and strong enough to pull the entire body through the holes, and traditional actuators used in robotics require rigid components, which limits the flexibility of the structure.