Octopuses are intelligent enough to be called the ‘genius of the invertebrate world’. With more than 300 scientific studies to date, experts have concluded that octopuses are ‘sentient creatures’. Despite being an invertebrate, what is the reason that the octopus has a high level of cognitive ability? The cause has recently been revealed, and the answer is that it has the same ‘moving gene’ as the human brain.
‘Learning DNA’ exists in octopus brain
Octopuses are very different from the structure of ordinary animals. Animals are usually bilaterally symmetrical, but octopuses are radial, ending with a head-foot. This is why octopus, squid, and octopus are called cephalopods. It also has three hearts, and the brain is located between the head and legs. Eight legs are equipped with well over 1000 suckers, each of which can be used like a hand.
An octopus with such a strange structure is very intelligent. However, the brain ability of a smart octopus has recently become an issue in the field of animal behavior. This is because it has been found that there are common genes in the brains of humans and octopuses. The study was conducted by an international joint research team composed of researchers from 7 countries including Germany, Sweden, India, the United States, Japan and Austria, as well as the Italian Academy of Advanced Sciences (SISSA).
The research team found that transposons similar to those present in the human brain are also present in the octopus brain. A transfer factor is a piece of gene (DNA) that can move from place to place within the genome (genome). They are also called ‘jumping genes’ because of their ability to move directly from one place to another. A whopping 45% of the human genome consists of transfer factors, which replicate themselves and insert themselves at a location in the chromosome.
Transposable factors can also cause genetic diseases. This is because the transfer factor causes gene mutations in the process of inserting it into a new location. Therefore, most of the transfer factors are usually inactive because their activity is inhibited by the cell’s defense action or loses the ability to move. However, as some transposable factors are activated and position shift occurs occasionally, they play an important role in conferring diversity of the genome, such as species differentiation and evolution, and regulation of gene expression. In particular, the regulatory function of changing genes to adapt to the changed environment is excellent.
Transposable factors were discovered in 1956 by American geneticist Barbara McClintock while studying corn chromosomes. She discovered that by changing the structure and location of the corn gene, the function of the gene could also be changed, and this type of genetic material was named ‘regulatory factor’. For this work, she was awarded the 1983 Nobel Prize in Physiology or Medicine.
Among the transfer factors, the one that exerts the most influence is what is called ‘Long Interspersed Nuclear Elements (LINE)’. This LINE transfer factor is related to cognitive abilities of the brain such as learning and memory. Many of these LINE transfer factors are found in the hippocampus, which controls the learning process in our brain, and this was also found in octopuses. Transition factors occupy a high proportion in the octopus gene. In particular, it is abundantly present in a part called the vertical lobe that plays the role of the human hippocampus. The research team found a very strong movement signal of the LINE transfer factor in the vertical lobe of the octopus brain.
The research team analyzed the brain genomes of the two most common octopus species, Octopus vulgaris and California two-spotted octopus (Octopus bimaculoides), using gene sequencing technology. As a result, it was found that the genomic transfer factors of the two species were similar and very abundant. Until now, most transfer factors have been thought to be inactive and merely traces of the past. However, through the two species of octopus, it was confirmed that the activity was still working in detail.
Professor Remo Sanges of Italy said, “The discovery of the LINE transfer factor active in the brains of two octopuses is evidence that these elements have specific functions, such as cognitive ability, beyond replication and pasting functions. It is very meaningful in
Octopus is a master of camouflage
The similarity between human and octopus brains is a prime example of remarkable convergent evolution. Convergent evolution refers to a phenomenon in which species that are taxonomically different, that is, species that are far apart, can independently evolve the same function to solve the same problem. The octopus brain is functionally similar to the mammalian brain. Therefore, Professor Sangess explains that the LINE transfer factor is a very interesting candidate that will help in the study of the evolution of intelligence in the future. The research results of the joint research team were published in ‘BMC Biology’, an international journal in the field of life sciences published by the British Medical Association.
Octopuses have 10,000 more genes than humans, and their brain structure is complex. It also has a retina that receives images very similarly, though not identical to our eyes. Thanks to these retinas, octopuses are strong at finding their way out of captivity. It cleverly climbs out of a small crevice in the fish tank and climbs up the water tank.
Octopuses are usually as intelligent as dogs. Because of their great intelligence, once they learn a certain problem, they memorize it and solve it easily if a similar problem occurs. They also know how to use their environment, so they show strategic behavior when hiding. It changes the skin color and pattern from time to time according to the surrounding environment. When attached to a rock, it changes color to the rock, and when it is next to a coral, it changes so much that it looks like a coral. This is why the octopus is also known as the chameleon of the sea.
Octopus skin consists of a complex internal structure that includes unique pigment cells and the muscles that control them. By controlling the muscles of this skin, it delicately changes the texture and color of the skin colorfully. The ability to perfectly camouflage not only the color but also the texture of the skin is a high-level function that is not easily found in nature. However, the specific mechanism is not known.
‘Indonesian octopus (Octopus Marginatus)’, which inhabits the coast of Sulawesi, Indonesia, disguises itself as a coconut, which is a palm tree, spreads under the sea when a natural enemy appears. While walking on the floor with two legs, it rolls its body like a ball on its six legs and moves like a coconut. The speed of running away is much faster than when using all of your legs to move. The octopus’s ‘walking on two legs’ camouflage breaks the common sense that ‘invertebrates cannot walk on two legs’. The wisdom of octopus camouflage to survive is simply amazing.