If you wanted to design an intelligent animal from scratch, you probably would not start with a creature that has no bones, three hearts and blue blood. Yet the octopus is one of the most remarkable problem-solvers in the animal kingdom.
In laboratories, octopuses have learned to unscrew jar lids to reach crabs inside. Some have escaped from their tanks at night, crept across the floor to a neighbouring tank to eat the fish, and then returned home before morning. In the wild, veined octopuses have been filmed collecting coconut shells, carrying them across the seabed and assembling them into a portable shelter – one of the few known examples of tool use by an invertebrate.
What makes this intelligence so surprising is how different the octopus brain is from ours. About two-thirds of its roughly 500 million nerve cells are not in its head at all but in its eight arms. Each arm can taste, touch and even make simple decisions on its own. Scientists are still debating what it might feel like to be an animal whose thinking is spread throughout its body.
The octopus's cleverness may be linked to its lifestyle. Without a shell for protection, it must outwit predators by hiding, changing colour in a fraction of a second, or squeezing through gaps no bigger than its beak. Survival depends on flexible thinking.
Strangely, most octopuses live only one or two years. They have no parents to teach them and usually die soon after laying eggs. Every skill they show, they must largely work out for themselves.
