Surprisingly the only non-vertebrate animal protected by the Animals (Scientific Procedures) Act is the octopus. Why? More and more research is pointing to the octopus as a relatively intelligent animal. They can remember mazes, use tools, solve complex problems and appear to have a rudimentary consciousness. Conducting research on their brains appears quite difficult as they can shut off blood supplies to an area of their body or brain at will. One researcher thought he had anaesthetised an octopus and placed an electrode in its brain … and then found the animal reached up and pulled the electrode out. Another octopus regularly short-circuited the light in its tank by squirting water at it (source).
Octopi brains are quite developed – they are lateralised, like mammalian brains, and also highly folded, greatly increasing the surface area. Some neurons are minaturised permitting more to be packed in.. One researcher, Jennifer Basil, plans to start looking for mirror neurons in a related species, the nautilus. If she finds them it might mean these ancient cephalopods are not as stupid as they look – they may be able to infer the emotional states of another animal, which might explain why one researcher said octopi seem to know what he is thinking. Spooky.