A few years ago, Germany’s Sea Star Aquarium began experiencing mysterious electricity blackouts. The problem baffled workers for days until they finally discovered the culprit—a nearly 1 meter (3 foot)-long octopus named Otto. The smart sucker had found a way to turn off the light above its tank. It shot a jet of water, which it would normally use to propel itself through the ocean, at the light. That caused a short circuit that shut down power to the entire aquarium.

Octopuses have been spied doing a lot of clever things, from playing with Rubik’s Cubes to opening tricky childproof jars. They seem to be surprisingly intelligent compared with other invertebrates—animals without backbones. And their smarts aren’t all that’s unusual about them. Octopuses have eight flexible arms lined with suckers that can taste as well as feel. Their arms can even regenerate, or grow back, if lost or injured. And the animals can change the color and the texture of their skin to match their surroundings.

Octopuses are unlike any other creature on Earth. Even their DNA seems alien. DNA is a molecule that carries hereditary information and acts like a blueprint to create an organism (see What is DNA?). Scientists recently deciphered the entire genetic sequence, or genome, of the California two-spot octopus (Octopus bimaculoides). What they found was bizarre—and could explain why octopuses have so many weird and wonderful adaptations. 

Octopuses don’t just look otherworldly. They also have abilities like those straight out of science-fiction movies. For instance, an octopus can camouflage itself to blend into its surroundings or mimic other organisms. Its skin is loaded with cells called chromatophores. They contain colorful pigments that get pushed to the surface when muscles surrounding the cells contract. This lets an octopus create a huge variety of patterns on its skin.

Chromatophores allow an octopus to change its appearance to look like a piece of seaweed or coral. That way it can hide from danger or lie in wait for its next meal. Some octopuses even transform their bodies to look like tasty crabs to lure in prey. Others disguise themselves as stinging jellyfish or venomous sea snakes, which predators typically avoid.

Scheel has found that octopuses also use their color-changing abilities for another purpose—to communicate. He observed the common Sydney octopus (Octopus tetricus) using colors to signal to each other during disputes off the coast of Australia. When two of the antisocial animals met, sometimes one octopus would stand up tall and turn a dark color while the other would crouch down and become pale. “They were communicating with their skin,” says Scheel. “One seems to be saying, ‘I’m big and tall and dark and serious, and I won’t back down.’ The other, ‘I’m pale because I don’t want a fight.’”

To find out why octopuses have so many alien-like features compared with other animals, scientists looked for clues within DNA by sequencing the octopus’s genome. Decoding an organism’s genome can help researchers learn how the animal evolved, as well as what genes it has and what these units of hereditary material do.

Scientists discovered two things about Octopus bimaculoides’s DNA that they believe allowed it—and other octopus species—to evolve so many unique characteristics. First, its genome appears to have been completely rearranged. “The organization of the genome, relative to all other animals scientists have studied, looked like it had been thrown into a blender,” says Clifton Ragsdale, a biologist at the University of Chicago who helped sequence the octopus genome. Octopuses also have an enlarged family of genes responsible for controlling whether an organism has a particular trait. Ragsdale believes this mixed-up DNA and the ability to turn different genetic traits on and off could have produced the animal’s many special adaptations.

Ragsdale’s team also saw a similar expansion of the family of genes involved in octopuses’ neuron development. Such an unusually large number of these genes might explain why the creatures are so much more intelligent than other invertebrates.

Ragsdale hopes to understand more about how these animals, whose brains are organized so differently from our own, perceive and react to the world around them. Since scientists have yet to study actual alien life, says Ragsdale, “the next best thing to alien intelligence could be the octopus.”