An octopus has a brain about the size of a nut. Three-fifths of an octopus’s brain-style neurons are not in their head though. They’re in their arms.

An octopus’s arms are so sensitive, they can not only touch, but they can taste with them. It is thought too that their colour-changing cells, the chromatophores, can process different wavelengths of light. This means their arms can also ‘see’. That’s three-fifths of the official senses which humans even have – in an octopus’s arms.

It’s hard not to try and imagine this out in our own bodies. Our toes could taste how sweet our chocolate milk was. Our butt cheeks could decide if we liked the shade of red on that dress. It’s another world, biologically-speaking, but it’s still our world.

Perhaps that’s why some people believe octopi are aliens. Really. I didn’t realise this until the other day. They really (and some are actual scientists) believe the closest thing to extra-terrestrial life on planet Earth is the octopus. I feel as though octopi have a right to know this – so they could at least confirm, or deny it. Except how would they? And what if it’s true? Those arms could surely work the controls of a space ship. Right?

Octopi are quite important in my life right now. I find myself looking for them. Not on Questie. It’s not like I’m looking for them in the fridge or under the covers. But when I’m swimming, then I look for them a lot.

There’s lots of them here. Particularly in the shallows. Octopi hide under the rocks and coral-encrusted objects which you get close to shore. Mooring blocks, old engines, pieces of metal. Sometimes you see them moving around in the open too. Octopus after all, spend a lot of time moving. This is because they hunt, rather than waiting for their food to come to them. That’s the pay-off for losing their shell.

Officially, they’re still in the phylum of invertebrates, the Mollusca. Molluscs typically have shells. Octopi lost theirs, evolutionarily-speaking. They didn’t just lose them like I’d lose my bank card. Again. No, they evolved to become shell-less, though they remain in this phylum of shelled-creatures. Confusing, no?

No wonder people think they might be aliens. It’s like if we arrived on another planet and, when stopped and questioned by the authorities, we put ourselves in the same group as that planet’s fishes. The inhabitants on that planet would be scratching their heads. ‘Are you really fish?’

We’d be nodding our heads vigorously. ‘See this hand? Wavy fingers? Very similar to a gill.’

The octopus is considered to be a specialised member of their class: the Cephalopoda. They are joined by somewhat similar species too, like the squid and the cuttlefish.

The octopus is just at the extreme end of this class. Indeed, it is considered the smartest of all the kingdom of animals without a backbone. With its brain in its arms maybe not surprising. When I swim, I’m going to look for its spaceship to go home.

https://www.independent.co.uk/news/science/octopus-aliens-scientists-theory-meteors-space-earth-cambrian-explosion-a8358631.html