In "Nezha 2", why did General Octopus dare to roast his own "feet" to eat?

Review expert: Li Yingchao, Director of the Science Popularization and Social Education Center of the Beijing Forestry University Museum, PhD of the Institute of Zoology, Chinese Academy of Sciences

The movie "Nezha: The Devil Boy Conquers the Dragon King" attracted many people to watch it with its shocking special effects and compact plot.

Among them, the scene where the octopus general roasted his own "feet" in the magma and shared them with the monsters around him left a deep impression on everyone. The audience couldn't help but ask: Why did the octopus general dare to "torture himself" like this? Was it made up by the director?

The octopus's "feet" are actually its "arms"

The octopus is a cephalopod mollusk, one of the most agile hunters among invertebrates. In addition, the octopus does not actually have "feet", its "feet" are actually arms.

The octopus's tentacles are not only long and powerful, but also covered with suction cups that can firmly adhere to the surface of objects, helping the octopus crawl, climb and even capture prey on the seabed.

Independent nerve cord

Each of the octopus's eight arms has an independent nerve cord. As long as the brain issues an abstract command to the arms, the arms can perform multi-threaded operations simultaneously, sense the environment independently, and respond quickly without the need for specific instructions from the brain. In other words, each of the octopus's arms has a complex and autonomous "brain".

Source: Beijing Zoo Conservation Education

It can both absorb and "feel"

The octopus's eight arms are lined with suction cups that can hold onto objects. The suction cups not only have the function of holding onto objects, but also have sensory organs, which allow the octopus to distinguish between targets and the surrounding water flow. Each arm has two rows of suction cups that can hold onto the surface of an object. When the octopus is resting, there will always be one or two arms on "duty," and the arms on "duty" will constantly move around to detect possible dangers.

Source: Beijing Zoo Conservation Education

In addition, when an octopus swims, it stretches its arms and legs and then quickly contracts them, creating adhesion between the sucker and the water. Then, the octopus contracts its tentacles' muscles to create negative pressure on the sucker, thereby pulling its body forward. This process is similar to an octopus "walking" in water.

Octopus General's "Self-service Teppanyaki" is not fiction

The "self-service teppanyaki" of the Octopus General is by no means fictional. The main reason why it dares to grill its own tentacles is that the octopus's tentacles have powerful regenerative abilities.

Stem cell reconstruction

The regeneration of octopus arms first depends on the mobilization and differentiation of stem cells. After the arms are damaged, the stem cells in the octopus are activated and migrate to the damaged area. These stem cells have the potential for multidirectional differentiation and can differentiate into various cell types, such as muscle cells, nerve cells, etc., to replace damaged or missing tissues.

Signaling pathway synergy

During the regeneration of octopus arms, multiple signaling pathways are activated and work synergistically. These signaling pathways include growth factor signaling pathways, Wnt signaling pathways, Notch signaling pathways, etc. They jointly guide the regeneration of octopus arms by regulating the proliferation, migration and differentiation of stem cells, and promoting processes such as angiogenesis and neural regeneration.

Epigenetic regulation

Epigenetic mechanisms affect cell fate and regeneration by regulating gene expression patterns. For example, epigenetic modifications such as DNA methylation and histone modification can affect gene readability and expression levels, thereby regulating the process of stem cell differentiation and tissue regeneration.

Energy metabolism adaptation

During the regeneration process, the octopus is able to ensure the energy supply required for regeneration by adjusting its own metabolic pathways, such as increasing glycolysis and aerobic oxidation. This adaptive mechanism of energy metabolism is crucial for the rapid regeneration of the octopus's arms.

In fact, this regenerative ability is not limited to octopuses. Many cephalopods have similar characteristics. However, octopuses are often better in regeneration speed and quality.

Recovery speed varies from fish to fish

The speed of an octopus's recovery after a broken arm is affected by many factors, including the species, age, health status, and environmental conditions of the octopus. In fact, the octopus has already started the process of vasoconstriction and blocking blood flow very shortly before the arm is broken, and gradually grows new arms in the next few weeks to months.

Taking the octopus Octopus eucophylla as an example, its arms and legs can be completely regenerated within 4 to 8 weeks, and the functions of the regenerated arms and legs are almost the same as the original arms and legs.

But this does not mean that they can break and regenerate their arms indefinitely. Frequent breaking and regeneration will cause a certain burden and damage to the physiological functions of octopuses, and may even affect their survival and reproduction. Therefore, when facing danger, octopuses usually choose other ways to escape instead of breaking their arms easily.

Tips: How to distinguish between octopus and squid?

In fact, squid and octopus are both cephalopods. Squid has 8 (4 pairs) arms and 2 (1 pair) tentacles, of which the tentacles have the function of retracting and are mainly used to obtain food. Octopus has only 8 (4 pairs) arms and no tentacles, commonly known as octopus. The ancestors of octopus actually also had tentacles, but their tentacles degenerated during the long process of evolution.

Octopuses have 8 arms Source: Qianku.com

Squids have 8 arms and 2 tentacles. Source: Ocean University of China Press

The suction cup of the squid is not directly connected to the tentacles, but is connected by a very short stalk. The suction cup is free and movable. The suction cup of the octopus is directly connected to the tentacles, is not free, and has no suction cup stalk. This point can be used to easily distinguish the two.

Octopus Sucker