The platypus, a unique egg-laying mammal native to Australia, faces many threats in the wild: climate change, predators, pollution, floods and shrinking freshwater habitats. For males, mating is a dangerous affair that involves wounding one another with their sharp, venomous spurs.
But scientists recently identified a male platypus that was just shy of 24 years old, the oldest recorded age for a platypus living in the wild, in an area that had experienced nearly seven years of drought in its lifetime. The discovery offers rare insight into one of the world’s most mysterious creatures and hints for how to help them live longer.
“We’re now getting a better idea of how they can live reasonable ages if the conditions are right,” said Geoff Williams, a biologist at the Australian Platypus Conservancy who helped study the platypus before returning it to its home.
Fast, slippery and dwindling in number, the platypus is difficult to study. There are about 300,000 of the animals remaining in eastern Australia and Tasmania. Special equipment is required to analyze and catalog them. The males’ venom can inflict monthslong pain to humans.
The age of an adult platypus is difficult to tell. When platypuses are young, changes to their bodies are more noticeable, allowing scientists to estimate the stage of development they are in. Once they mature, they barely change.
Scientists knew the age of the platypus they found in a small creek near Melbourne in September because they had given it a tag all the way back in November 2000, when they determined it was about 12 and a half months old, according to a paper published this week in Australian Mammalogy.
In captivity, platypuses have lived longer. The oldest known platypus recently turned 30 in a zoo in rural Victoria. But in old age, it was developing arthritis in one wrist, cataracts in both eyes and deafness — signs of aging that “may have precluded her survival if she were living in the wild,” the authors of the study wrote.
Scientists said the discovery of the oldest-known wild platypus, which broke a record previously held by a female last seen in New South Wales at 21, could help preserve the species. Specifically, studying its habitat, Monbulk Creek, offered some clues for conservationists.
One of the keys to the platypus’s long-term survival was a pool of water that persisted through the seven-year drought, Mr. Williams said in an interview. The platypus was living near a man-made reservoir that had supplied water to a local community in the southeastern suburb of Melbourne about a hundred years ago, giving it a refuge during long dry spells.
Conservation groups could aid other members of the species by identifying and strengthening populations near similar pools deep and large enough to hold water through droughts, he added.
“It’s important to make sure the population is still going,” said Gemma Snowball, a zoologist at Ecology Australia, an ecological consulting company that helped identify the platypus, “so everyone gets to see them and see that the iconic Australian species is still living in the wild.”
Scientists also said that the area’s low population density could have helped the platypus survive. A higher density could have led to more breeding and foraging activities, causing the animal to leave the water more often and risk predation, Ms. Snowball said. The male could also have taken more risks fighting over or defending a female.
Aside from its habitat, the animal itself also yielded some exciting new information for scientists about the distinctive species.
Throughout its lifetime, the platypus’s spurs had worn down to half its length, to 9.5 millimeters from 19, Mr. Williams said. The observation opened the possibility that scientists could use that feature to measure the ages of mature platypuses in the future.
“That’s something we hadn’t been able to confirm over a long period,” he said, adding: “If we could get a few more captures like that, we would be able to start to estimate what sort of decline takes place over time.”
For Mr. Williams, the discovery was also a sign that the threatened species might be more resilient than scientists had feared. In Monbulk Creek, “platypuses are highly endangered,” he said. “They could go extinct at any time.” Still, an animal there survived for a long time, remaining sexually competitive.
“It gives us much more hope,” he said, “that even if climate change predictions are correct, if Australia becomes a lot drier in some places, and if platypus populations are faced with the prospect of having to live for much longer in isolated areas, they can survive through fairly long periods of being put under pressure.”
