[100 Challenge] DanJi’s reding note_27

Science Dream's strangely immersive science book
a scientific story that automatically becomes smart when you read it
Author Kim Jung-hoon (Science Dream)
Publish The Quest
Published 2022.05.20.

Three pigmented bags called 'chromatopores' are each distributed on the surface if you look closely at the octopus's skin. These pigmented bags are surrounded by muscles shaped like balloons filled with black, red, and yellow dyes. When an octopus expresses the required color, it stretches the pigmented bag containing the dye. It's like inflating a dye-filled balloon to reveal the color of the dye. The octopus changes color by making patterns such as stripes or spots by stretching and shrinking these pigmented bags.
The red blisters under the chromatopores create colors other than black, red, and yellow. The proteins called Reflectin, which are distributed here, scatter light of a specific wavelength, which can have metallic structural colors such as blue or green (a color created by the physical structure that affects light, as seen in male peacocks or butterfly wings). Furthermore, the cell layer called "Corporeus Leucophores," distributed inside the skin, can reflect most light to create white. This is not all. The bumps surrounding the skin can bulge momentarily, expressing the texture that matches the surrounding environment.
As such, the exquisite harmony of the four cells and tissues mentioned above results from the octopus' ever-changing Nature. American marine scientist Roger Hanlon published a study showing that an octopus can change color 177 times in an hour. Due to this disguise, they have established themselves as successful mollusks distributed throughout the Earth's oceans without the protective gear called shells.
Protrusion: Expression of texture that goes well with the surrounding environment as it becomes bulging from moment to moment
Chromatophores: Pigment sachets filled with black, red, and yellow dyes
Red vesicles: There is a protein called Reflectin, which scatters light of a specific wavelength
LeCorporeal: Cellular tissue that reflects most of the light to make white

An octopus has a brain in its legs?!
However, scientists had a concern. When an octopus is known for being colorblind and cannot distinguish colors accurately, how can it recognize its environment and change its body to almost the same color? The answer to this question was discovered only relatively recently, in 2015. Dr. Desmond Ramirez, an animal behaviorist at the University of Massachusetts, realized that octopuses can sense the world with their eyes and skin. Dr. Desmond Ramirez experimented by removing skin tissue from two California spotted octopuses and successfully observed that their skin pigmentation sacs change in size depending on the brightness of light. Dr. Ramirez claimed that an octopus can quickly detect colors only with photoreceptors found in the skin rather than through the brain or central nervous system. He also discovered proteins called opsin and rhodopsin found in the retinal cells of the eyes in an octopus' skin. He explained that this is evidence that octopuses detect the world with their skin. There is no strange animal when it catches light and color with their skin.
Since then, the research on the octopus' nervous system has gained momentum, and the academic community has begun to report surprising findings one after another. An octopus' body contains 500 million neurons, 25,000 times more than the same mollusk, the snail. It is twice as many as a cat and resembles a dog. Of an octopus' 500 million neurons, only about one-third is found in the brain, which is even more surprising. Most of the remaining neurons are distributed in eight legs.
Dominic Sivitilli, a researcher in behavioral neurology at the University of Washington, argued at the 2019 "Conference AbSciCon 2019 in Cosmobiology" that an octopus judges situations independently rather than focusing on the brain. He explained that even if the brain is tiny, it can have superior cognitive and learning abilities compared to other animals. He noted that intelligent extraterrestrial life could have a different cognitive system, like an octopus, not a human.
In the same vein, Dr. Cheng Wen-Sung Chung of the University of Queensland in Australia said, "We can get a glimpse of the 'convergence evolution' of intelligence in cephalopods like octopuses." As bats and birds have different systems but evolved wings that can fly independently (convergence evolution), vertebrates and invertebrates also have separate systems. Still, humans have species intelligence on the one hand and octopuses (including cephalopods) on the other. Octopuses are truly unique in their intelligence among invertebrates.
Some scientists say that octopuses can use tools. Tentacles of the cone jellyfish were found on the sucker of the purple octopus in 1963. Based on this, a paper has been published showing that the purple octopus steals the cone jellyfish's tentacles and uses them as an attack or defense tool. Recently, it has been claimed that the coconut octopus uses tools. They carry coconut shells around and hide in them without suitable shelter. They sometimes use discarded plastic when there is no coconut.
Coconut octopus carries coconut shells for camouflage.
Marine zoologist Julian K. Finn argues that an octopus' use of tools is an intelligent behavior involving preparation or prediction for what will happen in the future. Frequent studies show that an octopus has observed the behavior of opening a bottle cap. In fact, in 2018, Nature published a paper on the 'ecological intelligence hypothesis' that the human brain evolved not from social cooperation but from fundamental survival activities to find, process, and avoid natural enemies. Interestingly, octopuses have intelligence, even though they are non-organizational and social animals. Why is this interesting? This is because the social intelligence hypothesis has formed a large axis when discussing the origin of intelligence. This hypothesis applies to animals with a certain level of intelligence, such as humans and chimpanzees. For example, it is argued that human ancestors in the past started to cooperate in groups and developed complex thinking, and based on this, they had more significant and more sophisticated brains.