What Happens When an Octopus Dreams?

Octopuses are known to shift hues on purpose in order to blend into a new environment, but a snoozing specimen in a home container has added a colorful twist to the world of cephalopods. A captive octopus named Heidi was caught on camera changing colors for no perceptible reason. She was seen clinging to the sides of her tank, twitching slightly, and turning from yellow to white to magenta to black. The display has some marine biologists suggesting that, like a dog twitching in its sleep as it dreams of chasing a squirrel, Heidi is color-coding herself according to her dreams. Of course, no one really knows whether cephalopods dream, but we do know that they have pigment sacs in their skin known as chromatophores, which expand or contract to change colors. These chromatophores are usually controlled by the brain, so it would be logical that the octopus's brain is deliberately rearranging its color scheme while it's asleep. According to the scientists, the shift might help the octopus maintain its defenses by appearing as more than just some static object on the sea floor.

The odd world of the octopus:

• Octopuses have three hearts, two of which pump blood to their gills, and one that pumps blood to their organs.
• The largest octopus is the giant Pacific octopus, which can weigh 600 pounds (272 kg) and boasts an arm span of 30 feet (9 m).
• Although all octopuses carry some type of venom, only the blue-ringed octopus is considered a threat to people; its bite can cause paralysis in minutes.