Orcas were once called "The Whale Killer" by sailors who often saw them attacking whales. Over time, the name was reversed. Orcas are also known as blackfish, sword whales and killer whales. Orcas do not have olfactory organs or a lobe of the brain dedicated to smell. They have good senses of sight and hearing. They hear better than dogs and even bats, using these abilities orcas practice echolocation. Echolocation is when Orcas make sounds and then listen to the echoes. Echolocation allows them to tell whether animals or objects are close or far away, and exactly how close or far away they are. Like dolphins, orcas cannot fall asleep completely, because they must come to the surface to breathe occasionally. So they sleep with only half their brain. If their left eye is open it means that the right side of their brain is awake and the other is asleep and spoiled