Pierre is a penguin in a penguin suit. A penguin swimsuit, that is.

The 25-year-old African penguin lives at the California Academy of Sciences in San Francisco but, until recently, he had been having a hard time enjoying the institute's water tank along with his fellow penguins.

The reason? He's been losing some of the waterproof feathers that penguins use to keep themselves warm while they swim and play. In fact, his pink rear end has become almost completely exposed.

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The scientists at the academy took pity on him as they observed him shivering on the sidelines while his 19 fellow penguins – a variety known as jackasses because they make noises similar to braying donkeys – jumped in and frolicked in the water.

Pam Schaller, a senior acquatic biologist at the Academy of Sciences and Pierre's chief minder, began racking her brain for a solution. She tried a heat lamp, but it wasn't entirely effective. Then she thought of the surfers who dive with their boards in the Pacific Ocean every morning and she had a brainwave. If surfers can wear a wetsuit, she thought, why can't a penguin?

She contacted a diving gear specialist across the San Francisco Bay in suburban San Leandro, and they were only too happy to come up with a workable design.

"We were really excited to do it," said Teo Tertel, marketing specialist aOceanic Worldwide, who are one of the biggest manufacturers of wetsuits worldwide. "We heard most of these penguins only live to 20, and our little buddy there was already 25. Anything we could do to help them, we were all for it."

The suit they came up with has a Velcro fastener at the back, covers the penguin's torso and has small openings for his flippers. It took several fittings to get the design just right. "I would walk behind him and look at where there were any gaps, and cut and refit and cut and refit until it looked like it was extremely streamlined," Dr Schaller said.

The experiment has proved to be a success. In the six weeks since Pierre started wearing the suit, he has been thriving, able to plunge into water and interact normally with his fellow penguins. He has gained weight and has even grown new feathers to help cover up that pink behind. His penguin friends don't seem to mind that he looks at bit different – they all have white stomachs while his, with the suit on, is black.

As his health has improved, he has also started taking dips with the suit off. Dr Schaller said it was hard to say if the suit contributed to his improved condition. But she added: "Certainly we were able to keep him comfortable during a period of time that would have been very difficult for him to stay comfortable."

In the wild, the jackass penguin is found only off the coast of southern Africa. Their numbers have decreased from 1.2 million birds in 1930 to 120,000 today.