![]() Octopuses also score high by this measure, roughly in the range of vertebrates, though not as high as mammals. This tells us how much an animal is “investing” in its brain. Human beings have many more-something nearing 100 billion-but the octopus is in the same range as various mammals, close to the range of dogs, and cephalopods have much larger nervous systems than all other invertebrates.Ībsolute size is important, but it is usually regarded as less informative than relative size-the size of the brain as a fraction of the size of the body. Large in what sense? A common octopus ( Octopus vulgaris) has about 500 million neurons in its body. First of all, these animals evolved large nervous systems, including large brains. “Smart” is a contentious term to use, so let's begin cautiously. They range from less than an inch in length to the giant Pacific octopus, which weighs in at 100 pounds and spans 20 feet from arm tip to arm tip.Īs the cephalopod body evolved toward these modern forms-internalizing the shell or losing it altogether-another transformation occurred: some of the cephalopods became smart. But at some stage during their evolution, they radiated-around 300 species are known at present, including deep-sea as well as reef-dwelling forms. As the only cephalopods without an external or internal shell and no hard parts except for a beak, they do not preserve well. The fossil record of octopuses remains skimpy. Octopuses, cuttlefish and squid belong to a class of marine mollusks called cephalopods, along with now extinct creatures called ammonites and belemnites. They are probably the closest we will come to meeting an intelligent alien. If we can connect with them as sentient beings, it is not because of a shared history, not because of kinship, but because evolution built minds twice over. Our most recent common ancestor is so distant-more than twice as ancient as the first dinosaurs-that they represent an entirely independent experiment in the evolution of large brains and complex behavior. Since my first encounters with these creatures about a decade ago, I have been intrigued by the powerful sense of engagement that is possible when interacting with them. Octopuses and their relatives (cuttlefish and squid) represent an island of mental complexity in the sea of invertebrate animals. Behind the arm, large round eyes watch you the whole time. The arm itself is alive with neurons, a nest of nervous activity. ![]() ![]() The arm is packed with sensors, hundreds of them in each of the dozens of suckers. It tugs your finger, tasting it as it pulls you gently in. The suckers grab your skin, and the hold is disconcertingly tight. ![]() You reach forward a hand and stretch out one finger, and one octopus arm slowly uncoils and comes out to touch you. This one is small, about the size of a tennis ball. You stop in front of its house, and the two of you look at each other. Shells are strewn in front, arranged with some pieces of old glass. Eventually it raises its head high, then rockets away under jet propulsion.Ī second meeting with an octopus: this one is in a den. #How many hearts does an octopus have skinThe creature's color perfectly matches the seaweed, except that some of its skin is folded into tiny, towerlike peaks with tips that match the orange of the sponge. As you make your way around the sponge, so, too, do those eyes, keeping their distance, keeping part of the sponge between the two of you. The only parts you can keep a fix on are a small head and the two eyes. Its body seems to be everywhere and nowhere. Tangled in one of these sponges and the gray-green seaweed around it is an animal about the size of a cat. ![]() You're amid a sponge garden, the seafloor scattered with shrublike clumps of bright orange sponge. Then you notice, drawn somehow by their eyes. Someone is watching you, intently, but you can't see them. Published by arrangement with Farrar, Straus and Giroux, LLC (U.S.), HarperCollins (U.K.) Adapted from Other Minds: The Octopus, the Sea and the Deep Origins of Consciousness, by Peter Godfrey-Smith. ![]()
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