Do octopus brains work like humans’—or is there another way to be smart?

Three hearts; blue blood; no skeleton; arms like tongues. These are just some of the alien features of octopuses, squid and cuttlefish — members of the cephalopod family. The outlandish list continues. Cephalopod skin can taste chemicals, sense light and change colour and texture rapidly. In many species, the sucker-covered arms can even regenerate.

These invertebrates have evolved independently from the vertebrate lineage for more than 600 million years. Their last common ancestor was probably a worm-like creature with a rudimentary nervous system and eye-like patches of light-sensitive cells. Despite this evolutionary gulf, vertebrates and these highly specialized molluscs share strange similarities. Their eyes, for example. “It’s eerie how similar they ended up,” says Cristopher Niell, a neuroscientist at the University of Oregon in Eugene. “The convergent evolution of the eye still blows my mind.”

Now, one similarity is spurring a boom in cephalopod neuroscience. Around 400 million years ago, cuttlefish, squid and octopuses diverged from the only other living cephalopods — the nautiluses. They then lost their protective shells and evolved brains that are uniquely large among invertebrates. These brains bestow the soft-bodied cephalopods with high intelligence. Cuttlefish, squid and octopuses have excellent memories, use tools and are adept problem-solvers; they have a concept of time and are capable of delayed gratification.

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