The World’s Oldest Wild Platypus Shocks Scientists at 24 Years of Age .NguyenNghia

When Geoff Williams found and tagged a one-year-old male platypus as part of a survey in November 2000, he probably didn’t anticipate ever seeing the animal again.

But more than two decades later, in the same creek system in the suburbs of Melbourne, Australia, scientists found the platypus once again. When Williams then studied the creature, it was an unlikely reunion—and one with historic significance: At about 24 years old, the platypus is the oldest ever to be documented in the wild.

“This one is just beyond all our expectations in terms of how old it was,” Williams, a biologist at the Australian Platypus Conservancy, tells the Guardian’s Emily Wind. “It’s remarkable that this animal is still doing as well as he is after all these years.”

Previously, the oldest recorded wild platypus was a 21-year-old female discovered in New South Wales. Typically, a platypus outside of captivity may only live between 10 and 12 years.

Wild platypuses face a number of challenges to their survival, such as climate change, floods, habitat loss and pollution. The egg-laying mammals also have to contend with predators, which can include hawks, eagles, Tasmanian devils, snakes and dingoes. During mating season, male platypuses are their own worst enemies—using venomous spurs, they’ll attack others of their own kind that are competing for female mates (though this doesn’t seem to be lethal).

This combination of threats and stressors makes the discovery of such a long-lived platypus all the more unusual. In a study published last week in Australian Mammalogy, Williams and other researchers describe the animal’s longevity, as well as other platypuses that have grown old in captivity.

The record-breaking platypus’ habitat, called Monbulk Creek, is small and isolated—it hosted between only 12 and 29 individuals in its waters from 1997 to 2007. The population’s male-to-female ratio is nearly one-to-one, meaning mating season competition isn’t so stiff, and the creek’s narrow channel could make it difficult for predators to hunt there.

Though this habitat may seem like a utopia, the aged animal still faced adversity. The platypus survived the Millennium Drought, which dried out waterways in southeastern Australia from 2001 to 2009, and it endured the serious flooding that followed.

“We did a lot of surveys there in 2007 that confirmed that the population was virtually not reproducing because the food supply was so poor,” Melody Serena, a conservation biologist and study lead author, tells the Australian Broadcasting Corporation’s Peter de Kruijff.

At 24 years old, the platypus (which is nameless, but is referred to as Male 01F6-03FF in the study) has aged somewhat comparably to those that live in captivity—which is a “much, much less stressful life,” Williams tells the Guardian.

Nine members of the species raised in captivity since their youth—four males and five females—have been known to live past 20 years. As of November 2023, the oldest male is 25, and the world’s oldest platypus, a female, is 30 years old. She “continues to feed normally and is healthy, apart from arthritis developing in one wrist and cataracts occurring in both eyes,” the study authors write. “Her muted response to loud noises suggests that she is also becoming deaf.”

If it hadn’t been for the male platypus’ original tag, scientists would likely not have known its exact age. Young platypuses show more physical changes as they grow older, but adults look largely the same, writes the New York Times’ John Yoon.

The IUCN lists platypuses as “near threatened,” and fewer than 300,000 remain in the world. This record-breaking platypus provides a hint to which conditions can enable the species to persist—even through drought and flooding.

“It’s important to make sure the population is still going,” study co-author Gemma Snowball, a zoologist at Ecology Australia who caught the male platypus last fall, tells the New York Times. “So everyone gets to see them and see that the iconic Australian species is still living in the wild.”