Octopuses have blue color blood, it contains hemocyanin, which is responsible for keeping them alive at extreme temperatures.
Each of the octopus's arms has a small cluster of nerve cells that controls arm movement, so they technically have 9 brains.
Octopuses are soft-bodied invertebrates – they don’t have bones, octopuses can regrow their arm or tentacle if they lose one.
Female octopuses die shortly after their eggs have hatched and male octopus typically dies a few months after the mating.
All octopuses have venom, when they catch prey, it breaks into shell and injects its venomous saliva into the prey to kill it