Life, but not as we know it. For all the scientific advances that humankind has made, we’re still grappling with some of the fundamental questions about life. Not just the distant, existential questions, such as the origins or meaning of life, but more immediate questions about life on Earth.
Are there limits to how long an organism can live for? Is it possible for a living creature to be immortal?
This week, we’ll consider these questions and explore some of the extremes of longevity in the natural world!
Index
Are there limits to longevity?
There are cases of biological immortality in the animal kingdom. A handful of species, including the aptly named immortal jellyfish Turritopsis dohrnii, are capable of passing back and forth between sexual maturity and immaturity.
In fact, even for humans, there may be no maximum lifespan. A recent study published in Nature, followed 4,000 ‘super-elderly’ people (105 and older) in Italy. The findings suggest that there may be a ‘mortality plateau’, which could imply that there is no limit to human longevity.
(People ageing from baby to 100 years old)
Shortest and longest living animals
No two lives are the same and, looking around the animal kingdom, we see massive variation in lifespans. Even between species that belong to the same class of animal, the difference in how long they live can be enormous.
To demonstrate this we’re going to delve into the shortest and longest lives of the natural world – from insects and fish to reptiles and mammals.
Insects
Shortest living
Species: Mayfly
- Scientific name: Dolania americana
- Distribution: Southeastern United States
- Lifespan: 5 minutes
Most species of mayfly, also known as Canadian Soldiers in the US, live for about a day. However, the adult life of a female Dolania americana lasts a matter of minutes. Talk about living for the moment!
It’s remarkable the species has survived, as the female must mate and lay her eggs before her short time is up.
Longest living
Species: Termite (queen)
- Scientific name: Reticulitermes
- Distribution: Europe, Asia and North America
- Lifespan: 50 years
(A queen termite full of eggs)
The record for insect longevity is also held by a female, the queen of the African mound-building termites. Having founded a colony, the queen can live for up to 50 years. They grow up to 8 cm in length and, at their prime, they can give birth to a massive 30,000 eggs per day!
Fish
Shortest living
Species: Dwarf pygmy goby
- Scientific name: Pandaka pygmaea
- Distribution: Southeast Asia
- Lifespan: 2 months
For the dwarf pygmy goby, as with the mayfly, time is of the essence. This minute reef-dwelling fish reaches sexual maturity just 40 days after hatching. In the remaining couple of weeks, the female still manages to lay around 400 eggs.
Longest living
Species: Greenland shark
- Scientific name: Somniosus microcephalus
- Distribution: North Atlantic and Arctic Ocean
- Lifespan: 400 years
(Rare footage of the Greenland shark)
According to a study in 2016, the Greenland shark can live for up to 400 years, making it the longest-lived vertebrate on Earth.
Widely distributed across the North Atlantic and Arctic Ocean, these sharks are slow developers. They grow at a rate of around 1 cm per year and hit sexual maturity at around 150 years of age!
Reptiles
Shortest living
Species: Panther chameleon
- Scientific name: Furcifer pardalis
- Distribution: Madagascar
- Lifespan: 12 months
There are around 200 distinct chameleon species, all of which live in tropical, temperate climates. Panther chameleons, endemic to Madagascar, have the shortest lifespan of them all. Typically they live for around a year.
Due to the brevity of their lives, the entire adult generation dies before the new generation has even hatched from their eggs.
Longest living
Species: Aldabra giant tortoise
- Scientific name: Geochelone gigantea
- Distribution: Seychelles
- Lifespan: 200+ years
Aldabra giant tortoises take their names from the islands of the Aldabra Atoll in the Seychelles. As well as being one of the largest tortoises, they are also the longest living reptile. There have been many claims through history as to which was the oldest tortoise, but such claims are difficult to verify because the tortoises tend to outlive their human observers!
Nevertheless, the longest recorded lifespan (255 years) belongs to Adwaita, who lived in Kolkata Zoo in India from 1750 to 2006.
Mammals
Shortest living
Species: Muller’s Giant Sunda Rat
- Scientific name: Sundamys muelleri
- Distribution: Indonesia, Malaysia, Myanmar, the Philippines, and Thailand
- Lifespan: 6-12 months
According to the longevity records, a comprehensive database of animal lifespans, the shortest living of all the mammals is the Muller’s Giant Sunda Rat. This little rodent, which belongs to the muridae family, is found across South East Asia.
Although it can live for longer in captivity, in the wild it generally lives for around six months.
Longest living
Species: Bowhead whale
- Scientific name: Balaena mysticetus
- Distribution: Arctic and sub-Arctic waters
- Lifespan: 200 years
(Images from research on Bowhead Whales in the Arctic)
Bowhead whales have a number of claims to fame. Not only are they the longest living mammals on Earth, but they also have the biggest mouth of any animal and a tongue that ways close to 1000 kg!
This species has also attracted attention from the medical world as these whales seem to be almost entirely resistant to cancer.
A giant tortoise believed to be extinct for 100 years mysteriously found in Galápagos https://www.knowledgeinflux.info/2019/06/a-giant-tortoise-believed-to-be-extinct.html