Perhaps two of the most interesting discoveries about octopuses, though, is that they have three hearts and nine brains. There may be many types of octopus, but they all have a truncated anatomy.

Recent studies have made significant strides in mapping the diversity of cell types within cephalopod brains. For instance, research on the octopus Octopus vulgaris has created a detailed cell ...

Over half of the neurons in Octopus vulgaris, about 300 million, are not in the brain at all, but distributed in "mini-brains," or ganglia, in the arms. Within the central brain, most of the ...