Octopuses have three hearts. One is for the body and the other two pump blood through the gills.

Octopus can be easily distinguished from other squids because they have eight tentacles. This is why they are called octopus, because the Greek word "okto" means eight and "puos" means foot. If they feel threatened, they release an ink-like liquid, which spreads in the water like a huge, dark cloud. The octopus can thus disguise the direction of its escape. Moreover, the animals are masters of camouflage because they can instantly change their body colour from grey-brown to blue-green, red or pink.