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
Blue whale penis dubbed "a real Moby Dick". The specimen is just the tip, as the entire organ, when intact, would have been about long and weighed about , well above average for even a blue whale. By comparison, an adult elephant's penis is the largest penis of any land animal at on average. Blue whale penis The blue whale has the largest penis in the animal kingdom. It is commonly cited as having an average penis length of to and a diameter of to . The reported average penis length varies but is usually mentioned to have an average length of .