The octopus has long been recognized as one of Earth’s most unusual creatures. Its intelligence, dexterity, and complexity are unparalleled among invertebrates. And, until last year, scientists had never fully mapped the genome of the octopus, so the eight-armed creature’s full genetic code remained a mystery.
Finally, in a journal article published in Nature this month, an international team of researchers from the U.S., Germany, and Japan describe the genetic composition of one octopus species—the California two-spot octopus.
“The octopus appears so utterly different from all other animals, even ones it’s related to, that the British zoologist Martin Wells famously called it an alien,” said neurobiologist Clifton Ragsdale, the study’s co-leader. “In that sense, you could say our paper describes the first sequenced genome from an alien.”
The researchers’ findings were full of surprises. For example, the scientists documented a total of 33,638 protein-coding genes in the octopus genome, which is about 10,000 more genes than found on the human genome.
The analysis also revealed “hundreds of cephalopod-specific genes” that are specific to the octopus family and not found in any other creatures.
“The suckers, for example, express a curious set of genes that are similar to those that encode receptors for the neurotransmitter acetylcholine,” wrote Alison Abbott, Nature’s Senior European Correspondent. “The genes seem to enable the octopus’s remarkable ability to taste with its suckers.”
In the journal article, the scientists described the octopus and other cephalopods as “remarkably sophisticated,” with a plethora of advanced features.
“Coleoid cephalopods (octopus, squid and cuttlefish) are active, resourceful predators with a rich behavioural repertoire,” they said. “They have the largest nervous systems among the invertebrates and present other striking morphological innovations including camera-like eyes, prehensile arms, a highly derived early embryogenesis and a remarkably sophisticated adaptive colouration system.”
Did the highly-advanced octopus evolve from other species? Compared to creatures purported to be in its evolutionary lineage, such as mollusks, the octopus is much more complex and intelligent—extraordinarily dissimilar from anything else.
“Soft-bodied cephalopods such as the octopus show remarkable morphological departures from the basic molluscan body plan, including dexterous arms lined with hundreds of suckers that function as specialized tactile and chemosensory organs, and an elaborate chromatophore system under direct neural control that enables rapid changes in appearance,” the researchers explain in their journal article.
“The octopus nervous system is vastly modified in size and organization relative to other molluscs,” they added.
The striking dissimilarity of the octopus inspired some of the scientists behind this latest research to describe the creature as “the pinnacle of an evolutionary track alternate from man.”
“Very simple molluscs like the clam—they just sit in the mud, filtering food,” said Benny Hochner, a neurobiologist and octopus researcher in Israel. “And then we have the magnificent octopus, which left its shell and developed the most elaborate behaviors in water.”
Other scientists remain unconvinced that Darwinian evolution can even account for the octopus. In an article published on Friday, scientists at the non-profit Discovery Institute argued that this recent octopus research shows how evolutionists struggle to make sense of these eight-armed enigmas.
“How could so many unique genes arise by blind neo-Darwinian processes?” the article asks. “It’s unsatisfying to hear scientists assume they ‘developed’ somehow.”
“Scientific investigation can still be ‘very exciting’ without the Darwinian angle,” the Discovery Institute scientists posit. “There are many more species of cephalopods worth investigating. Some live deep at hydrothermal vents. Some live in shallow tide pools. They come in all sizes. The mimic octopus amazes scientists. There is much to occupy biologists’ time learning about these wonderful animals, without having to fit them into an evolutionary tree.”
Astonishingly complex creatures like the octopus do not back up evolution, the Discovery Institute argues. Rather, they point to something else: design.
“It’s unlikely to be productive trying to trace an assumed evolutionary ancestry that requires heavy doses of ‘innovation’ or ‘convergence’ to accept,” they say. “Why not tackle the questions amenable to observation and understanding? Biomimetics is showing the usefulness of a design approach. Let’s follow that evidence where it leads.”