Meet Pesto: the fat baby penguin and viral superstar

Born in January weighing only 200g (7oz), the nine-month-old king penguin is now more than a hundred times the size. At a whopping 22.5kg (50lb), he is the biggest chick the aquarium has ever seen.

It is normal for penguins to stack on some “healthy baby chub” after they hatch, the aquarium’s Jacinta Early tells the BBC, but keepers had no idea Pesto would become this big.

“It’s a combination of nature [and] nurture, really,” the marine biologist explains.

Pesto’s biological father is quite tall, but he’s also been very well looked after by his foster parents Tango and Hudson: “He eclipses them now, which also makes him look comically large.”

Hand-fed several times a day, Ms Early says Pesto’s considerable heft is also partly attributable to his “very healthy appetite” – a gentle way of saying he gobbles up to 30 fish daily.

But she stresses he’s healthy – essentially half fluff – and he’ll soon begin to drop weight naturally.

“If I poked him, my entire finger would completely [disappear] deep in his feathers,” Ms Early says.

“When he does start to fledge, he’ll lose a lot of that baby fluff, and he’ll also lose much of that weight, so he’ll slim down nice and sleek.”

He’s already losing a smattering of his baby feathers, but she says there’s much more to Pesto than his cuddly appearance anyway.

She describes him as a social butterfly who chatters away in a “cute little whistle tone” and loves annoying the adult penguins “like any typical toddler would”.

“He tends to be the first one to kind of say hi [to keepers] and he also does respond to his name.”

“We definitely do have our favourites,” Ms Early says, diplomatically. “[But] Pesto seems to be a little bit in love with all the keepers as well.”