Of the approximately 100 species of cuttlefish, the Australian giant cuttlefish is the largest cuttlefish in the world. They can grow almost five feet long and weigh almost 30 pounds.
The coolest thing about these colossal cephalopods is their ability to change color for a number of reasons, including aggression, excitement, camouflage, or mating. They can change color so effectively that they can become almost entirely invisible when hiding among rocks and in caves. When they want to be noticed, they can put on a brilliant display of colors and flashes, particularly during the winter mating season.