For the first time, researchers have decoded the entire octopus genome, revealing significant differences between the genetic coding of cephalopods and other related invertebrates.

A team of researchers from the United States, Germany and Japan sequenced the genome of the California two-spot octopus (Octopus bimaculoides), a species that is relatively easy to raise in captivity. Their accomplishment is detailed in the journal Nature.

Because the creature's genome is so large, the work took several years. Contrary to expectations, the octopus didn't come by its sizable genome via whole replication. Some species double up their entire genome, but the California two-spot octopus evolved entirely new sequences of code over its millions of years of existence.

The species' genome boasts 2.7 billion base pairs. Human's have 3 billion.

In sequencing the octopus's entire genome, researchers were able to annotate the animal's code -- highlight the most unique sections and isolate codes more likely to be responsible for its variety of remarkable physiological capabilities.

Octopuses are most famous for their ability to change color and appearance. Their dynamic and adaptable camouflage skin has even inspired a variety of smart technologies.

"We've found hundreds of novel genes that don't have counterparts in other animals and may be involved in this unique camouflage process," Daniel Rokhsar, professor of molecular and cell biology at the University of California, Berkeley who helped lead the sequencing project, explained in a press release.

The octopus's camouflaging ability is made possible by its impressive intelligence, the source of which is also to be found in its expansive and unique genetic code.

"They were the first intelligent beings on the planet," said Sydney Brenner, the founding president of Japan's Okinawa Institute of Science and Technology Graduate University. Brenner was vital in initiating the international sequencing effort.

Intelligent is a relative term, of course, but the new research offers hard data on that front. Scientists found the octopus genome to possess 168 protocadherins, the genes believed to regulate the development and interactions of neurons -- that's ten times more than the amount found in most invertebrates and double the number of protocadherins found in mammalian genomes.

"We have already found several gene types that are dramatically expanded in the octopus relative to other vertebrates, and we think they play a critical role allowing a new level of neuronal complexity to be reached in invertebrates," Rokhsar said.

Researchers aren't anywhere close to being done processing the significance of the new codes.

But in order to sort out the connections between genes and the octopus's most compelling biological oddities -- the ability to regenerate limbs, the camera-like eyes, the animal's three blood-pumping hearts -- researchers need to sequence the genomes of other octopus species.

"The reason for looking broadly at several different types of cephalopods is to see what is conserved among them," Rokhsar added. "What is similar among all cephalopods is probably important to being a cephalopod."