There are no friends quite as loyal, quite as adorable, quite as likely to be distracted by a laser-dot on the floor for fifteen minutes straight, as our pets.

Dogs and cats, are incredibly popular pets. The only issue with them, as any canine- or feline-lover will tell you, is that they just don’t live as long as we wish they could. The average life expectancy for a dog varies by breed from 12.7 years (for a Jack Russell Terrier) to just 4.5 years (French Bulldogs). With cats, meanwhile, it’s up to around 15 years.

There are remarkable exceptions to these rules, though: In May 2023, a cat named Rosie, of Norwich in England, had a salmon cake to celebrate her 32nd birthday!

Orcas, Parrots And Other Surprisingly Long-Lived Animals

Some exotic pets can live much longer. Different breeds of parrot, for instance, have lifespans so long that owners also tend to need to make contingency plans for when they’re outlived by their feathered friend. The oldest recorded parrot was Cookie the cockatoo, who lived to be 82. Even more remarkable, though unverified, is the tale of Charlie, the blue-and-gold macaw, who supposedly lived to 114 years old and was once owned by Winston Churchill himself!

The average human life expectancy at birth is approximately 73 years, according to the World Health Organization. Species that can match or beat this tend to be the exception, not the rule. In such cases, unique individuals such as Cookie make headlines. Another potential example is the remarkable orca dubbed Granny, who reportedly led a Pacific Northwest pod of orca and is believed to have died in 2017, at an age of perhaps up to 105.

Remarkable longevity has been noted in many species, but as with Granny, the issue of accurate age verification remains. On top of which, particular specimens that live to extraordinary ages for their species don’t get us any closer to tackling the true heart of the issue: which animal species live the longest?

When it comes to the longest-living animal species, the answer is quite complicated.

Jell-ous Of Their Lifespan?

There are a lot of factors to consider, one being how we choose to define a life span. From birth to death seems simple enough, yes, but some sneaky creatures have a phoenix-esque ability to reset that process and become “infants” again.

The Immortal Jellyfish, as its impressive name implies, could, theoretically, live forever. It’s not the most imposing of creatures, at a teeny 4.5 millimeters in length, but it has one of the most astonishing and enviable abilities in the animal kingdom.

It grows from a larva to a polyp to a medusa (think child to teenager to adult in our terms), as is the norm for so many jellyfish species. What sets Turritopsis dohrnii and a select few other species like the moon jellyfish apart, though, is the fact that the medusa can also revert back through those stages. The creatures seem to be able to activate this state at will, as a response to threats to their lives. They are also able to do so repeatedly (more research is required to discover just how many times)!

Turritopsis dohrnii

Turritopsis dohrnii, also known as the immortal jellyfish.

Such jellyfish, then, have the potential to be the longest-living animals on Earth. It’s important to note, though, that they seem to have several regular-length lives, rather than one long lifespan.

The Humble Clam That Beats Them All

When it comes to remarkable lifespans, the Galápagos Tortoise is one of the most famous examples. Who could forget the story of Australia Zoo’s beloved Harriet, who was reportedly acquired at her homeland by Charles Darwin himself in the 1830s? She went on to become one of the zoo’s most famous residents (which is saying something, considering it was also the home of wildlife icon Steve Irwin), passing away in June 2006 having celebrated her 175th birthday the previous year.

These great tortoises, which can reach around five feet long, are noted by National Geographic to be among the Earth’s longest-living terrestrial animals. A century or so is nothing special for a Galápagos Tortoise, and though Harriet was the oldest on record, there may well have been others of her species who outlived (or will outlive) her.

What of ocean-dwelling animals? Like the immortal jellyfish, there are other species that live to incredible ages under the sea. The Wildlife Trusts declares the ocean quahog, a bivalve mollusk that frequents the beaches of the United Kingdom to be “the longest-lived animal known to man,” stating that one verified clam lived to an extraordinary 507 years old!

This, of course, far outstrips Harriet the tortoise’s extraordinary life, but before the clam claims the crown and hurries away (though clams don’t tend to be renowned for “hurrying” anywhere), there are other ocean dwellers to consider.

The Hexactinellid sponge may be the ultimate example: The cold of the Antarctic reportedly slows their growth to a glacial pace, and allows these curious creatures to live for a long, long time indeed: In one instance, a particularly large sponge was thought to be 23,000 years old, though the logistics of it all made determining this accurately impossible. Even 15,000 years, a revised estimate, could be far too generous, but astonishing to even think about nonetheless.

The National Ocean Service regards the quahog as the longest-lived animal on Earth, celebrating the bowhead whale, which can live for more than 200 years, as the runner-up. Whales in general, it notes, have the greatest lifespans of any mammals.

In terms of animals and lifespans as they tend to be defined, the humble ocean quahog is the world’s longest living animal. The sponge may take the prize if the discussion is expanded to living beings of any description, but for now at least, it’s proven too difficult to determine that with certainty.

Yet more contenders exist for that prize: In Oregon’s Malheur National Forest lives a vast honey mushroom cluster. Its exact age is also unknown, but science puts its lifespan at around 8,650! The candles on that cake would be a sight to behold indeed.

By Chris Littlechild, contributor for Ripleys.com

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