Oceanic dolphin another indication of animal intelligence. Killer whales have the second largest brain mass of any animal on earth, next to the sperm whale. The brain to body mass ratio in some is second only to humans. Self-awareness is seen, by some, to be a sign of highly developed, abstract thinking. Self-awareness, though not well-defined scientifically, is believed to be the precursor to more advanced processes like meta-cognitive reasoning (thinking about thinking) that are typical of humans. Research in this field has suggested that cetaceans, among others, possess self-awareness. The most widely used test for self-awareness in animals is the mirror
Gray whale where she was rushed to SeaWorld San Diego. After 14 months, she was released because she also grew too large to be cared for in the existing facilities. Reaching and , J.J. was the largest creature ever to be kept in captivity. Gray whale The gray whale ("Eschrichtius robustus"), also known as the grey whale, gray back whale, Pacific gray whale, or California gray whale is a baleen whale that migrates between feeding and breeding grounds yearly. It reaches a length of , a weight of , and lives between 55 and 70 years. The common name of the whale