Widespread around the world, playful yet graceful dolphins inhabit not only our seas and oceans but some river ecosystems, such as the Amazon and Yangtze, too. In total, there are about 40 species still living in the wild with the largest being the fierce 10 ton killer whale. In contrast, Maui’s dolphin, the smallest, weighs in at just 50 kilograms.
Renowned for their intelligence, dolphins have sleek, streamlined bodies and are very fast, agile and powerful swimmers. Highly sociable, the aquatic mammals live in pods and communicate through a variety of clicks and whistle-like sounds, also using echolocation to catch prey and avoid predators.
What Is the Average Lifespan of a Dolphin?
In the wild, dolphins can live up to about 40 though some species, such as the killer whale, can even reach the age of 80 on rare occasions. On average, however, a dolphin’s lifespan is usually around 20 to 25.
This varies considerably though depending on not only their aquatic environment and species but on the availability of food and their social structure too. For instance, while a freshwater Amazon river dolphin generally lives to around 15 or 20, the oceanic striped dolphin enjoys a life expectancy of about 50 to 60 years.
Dolphin Lifespan in Captivity
Although criticism and campaigns against keeping them in captivity continue to grow, thousands of dolphins of different species still live in zoos, theme parks and aquariums around the world. Unlike many other kinds of animal, dolphins actually have a much reduced lifespan in captivity due to the small enclosures, stress and their reduced quality of life.
Killer whales for example usually only live into their 20s in captivity with bottlenose dolphins also having a much lower lifespan and a shockingly low survival rate at birth. In aquariums, they live on average to the age of 12 whereas in the wild they generally reach 20 to 30 years old. The oldest on record to date clocked in at over 67 when she was last sighted.
The Life Cycle of a Dolphin
While some species of dolphin only mate and are fertile for a short period, others breed throughout the year. In general, the gestation period lasts between 10 to 17 months with mothers usually only giving birth to one calf, who normally arrives into the world tail first.
After a couple of minutes, the calves can both breathe and swim independently and proceed to stick closely to the side of their mother who feeds them with her fatty milk. Females typically nurse their young for anywhere between 6 months to 2 years with the calves also adding crustaceans and fish to their diet in this time.
The young dolphins then stay with their mother and travel in the same pod until they reach puberty between the ages of 5 to 10, depending on the species. Once they are old enough to mate, they then leave the nursery group and join a juvenile pod with individuals their own age.
The pod dynamics and structure are very fluid and flexible with super pods sometimes forming over 1,000 dolphins!
Probable Causes of Dolphin Deaths
While dolphins are sometimes hunted in places, such as Japan and the Faroe Islands, most fatalities are due to either habitat loss or marine pollution. Getting tangled in fishermen’s nets also poses a considerable risk to dolphins who are often caught unintentionally as by-catch.
Due to human encroachment, waste and development projects, dolphins residing along the Amazon, Ganges and Yangtze rivers are now critically or seriously endangered with some even being at risk of extinction. Offshore constructions and the substantial increase in shipping over the last decades have also led to a decline in dolphin populations.
This is because the increased noise and activity levels stress out and confuse the dolphins while the chemical pollution and plastic rubbish wreaks havoc both on their bodies and their environment.
Aside from humans, dolphins have few marine enemies with only a couple of shark species preying on young and vulnerable calves.
What are the Oldest Known Dolphins?
Nicklo – The oldest known dolphin in the wild, the 67-year-old Nicklo was last spotted swimming around Sarasota Bay in Florida in 2017. Now presumed to be dead, she birthed at least 4 calves throughout her life, the last at the astonishing age of 48.
J2 Granny – Although some researchers put her age at 105, which would make her the oldest killer whale ever, most now agree that Granny was actually several decades younger when she died. The main star of a BBC documentary, she was instantly recognizable from the gray ‘saddle patch’ behind her dorsal fin.
Nellie – Quite unusual for captive dolphins, Nellie lived to the ripe old age of 61 at Marineland park in Florida. Born in a small saltwater pool in 1953, she entertained live audiences for decades with tricks and shows and helped educate people about dolphins and their natural habitats.