In sperm whales, there is the greatest sexual dimorphism in terms of length and weight among all cetaceans. Both sexes are about the same size at birth (3.7 to 4.3 meters long), but mature males are typically 30 to 50 percent longer and three times as massive as females.
Typical values in this regard for females are 1100 centimeters and 15.000 kilograms and for males, 1500 centimeters and 45.000 kilograms.
Female sperm whales reach physical maturity at about 10.6 to 11 meters in length and generally do not reach more than 12 meters in length. The largest female sperm whale measured 12.3 meters in length. Males reach physical maturity at 15-16 meters in length, and larger males can reach 18-19 meters. There are reports of individual sperm whales reaching even greater lengths, with some historical reports even claiming a length of 24 meters.
