An article published in the journal “Nature” describes a research on octopuses. The DNA of a speciment that belongs to the species California two-spot octopus (Octopus bimaculoides), which lives off the coast of California, has been sequenced, the first case involving an animal belonging to the class of cephalopods. Octopuses are very different from all vertebrates, so much as to be defined aliens by various scientists, and showed remarkable intelligence. This species has about 33,000 protein-encoding genes, while humans have fewer than 25,000.

Octopuses are especially interesting animals to study for their physical and mental characteristics. They have three hearts, tentacles that can regenerate, skin that can change color and have no bones. They can solve complex problems showing an intelligence that evolved in an aquatic environment from a genetic line quite different from that of mammals.

A team of researchers from the Science and Technology Graduate University (OIST), the University of Chicago and the University of California, Berkeley have sequenced and analyzed the genome of a California two-spot octopus. They found that it resembles in many ways that of other marine invertebrates but contains some features that explain the uniqueness of its nervous system.

The researchers found that almost half of the genome of the octopus is composed of transposons, the so-called jumping genes, a very high percentage. In particular, there is a large quantity among the genes related to the animal’s nervous system. Given that they’re moving within the DNA, they’re not grouped together like in other animals.

The genes, but also the anatomical features of the octopus, show an evolution of its nervous system very different from the one that occurred in vertebrates. The axons, which are nerve fibers, of the vertebrates are covered with myelin, a fatty tissue that helps to speed the transmission of neural signals. Octopuses have no myelin and their nervous system has evolved based on local neural communications. For example, the tentacles can act independently thanks to sufficiently complex nerve centers.

This is just one of the results of the first genetic analysis carried out on the octopus after the sequencing of its DNA. The work has just begun because of the complexity of its genome and the considerable differences compared to that of vertebrates, which are better known. Precisely for this reason, the scientists involved in this research are very excited to continue the analysis, possibily of other cephalopods as well.