Dwarf sperm whale modern day whale. Characteristic of sperm whales, the left nostril is markedly larger than the right, and it has a spermaceti organ on its skull. The brain weighs around . The eyes are adapted for low-light environments. The dwarf sperm whale has 14 to 24 teeth, rarely 26, in the lower jaw that are sharp, slightly curved backwards, and–like other sperm whales–lack enamel. The teeth rarely exceed in length, smaller than those of the pygmy sperm whale. At most, 6 teeth are in the upper jaws, though in modern sperm whales, upper teeth are defunct. Unique to "Kogia", there is
Mammal at approximately the ⅔ or ¾ exponent of the body mass. Comparison of a particular animal's brain size with the expected brain size based on such allometric analysis provides an [[encephalization quotient|encephalisation quotient]] that can be used as another indication of animal intelligence. [[Sperm whale]]s have the largest brain mass of any animal on earth, averaging and in mature males. [[Self-awareness]] appears to be a sign of abstract thinking. Self-awareness, although not well-defined, is believed to be a precursor to more advanced processes such as [[metacognition|metacognitive reasoning]]. The traditional method for measuring this is the [[mirror test]], which determines if