Octopuses are the superstars of the invertebrates because of their astonishing intelligence. They’re considered mollusks, like clams or snails. Mollusks probably first appeared about 550 MYA and remained relatively simple, at least in the organization of their nervous systems, for hundreds of millions of years. One branch, the cephalopods, eventually evolved a complex brain and sophisticated behavior and may have reached something close to the modern form of an octopus around 300 MYA.
Octopuses, squid, and cuttlefish are true aliens with respect to us. No other intelligent animal is as far from us on the tree of life. They show us that big-brained smartness is not a one-off event, because it evolved independently at least twice—first among the vertebrates and then again among the invertebrates.
If we ever do meet extraterrestrial intelligent life, I am 100% certain we will kill them. How do I know? Just look at how much disdain and disrespect we have for alien creatures right on our own planet. We kill them indiscriminately.
I used to ask, if animals could talk, would we still eat/kill them? And, sadly, I believe the answer is yes, because we kill everything, even each other. Nothing is safe.
@Lesley if we meet ET life, we may very well not even recognize it as such. I doubt an ET intelligence would be something we could communicate with. We can't even communicate meaningfully with intelligent creature that are relatively close to us such as dolphins. How could we communicate with completely alien creatures that may live 10000 more slowly or more rapidly, or communicate through microwaves, etc?
@Emmanuel Florac I suspect we would communicate mathematically or graphically? We do communicate with dolphins by sound or hand movements, but that's more us communicating with them, not the other way around. But you're right; we're shit at understanding life forms different from us.