The common bottlenose dolphin (Tursiops truncatus) is among the most widespread and recognized marine mammals. They inhabit temperate and tropical waters worldwide, from coastal bays to the open ocean. The physical size of this species is highly variable, influenced by their environment and genetics.
Typical Length and Weight
Adult bottlenose dolphins generally fall within a length range of 6 to 13 feet, though most individuals average between 7 and 9 feet long. Their weight is equally broad, ranging from 300 to 1,400 pounds. On average, adult dolphins weigh between 485 and 595 pounds.
The maximum recorded size for a bottlenose dolphin was an individual from the Eastern North Atlantic, which measured approximately 13.5 feet in length and weighed up to 1,400 pounds. Calves are born much smaller, measuring between 2.6 and 4.6 feet long and weighing 20 to 66 pounds.
How Geography Affects Size
Differences in size are primarily driven by the existence of distinct ecotypes adapted to different habitats. Coastal bottlenose dolphins, which live in warmer, shallower waters like bays and estuaries, are generally smaller and lighter, reaching about 8 to 9 feet in length.
Offshore dolphins, which inhabit deeper, cooler waters farther from the coast, are typically larger and more robust. Their increased size, including a thicker layer of blubber, is an adaptation that helps them conserve heat in colder environments. These offshore individuals can reach lengths of up to 12 feet.
Within any given population, sexual dimorphism also contributes to size variation, as males are usually slightly larger than females. Males typically show larger measurements compared to females of the same age. This difference is thought to be related to their mating strategies.
Growth Rate and Lifespan
Bottlenose dolphins are long-lived mammals, with a lifespan ranging from 40 to 60 years. Females often live longer than males, with some individuals living past 60 years, while males typically live into their 40s.
The majority of a dolphin’s growth occurs during the first nine years of life. Females typically reach sexual maturity earlier (between 5 and 15 years old) than males (around 9 to 13 years). Both sexes generally reach their full physical maturity and asymptotic size between 12 and 15 years of age.
Growth in length slows significantly for females after about 12 years, but males may continue to increase in length and mass at a reduced rate for a longer period. The maximum size an animal attains is linked to its environment and the duration of its life.