A large, world-famous penguin is going through some changes. Pesto, the fuzzy King penguin and social media sensation from the Sea Life Melbourne Aquarium in Australia is beginning the natural molting process. It’s completely normal, but the fluffy bird looks a little bit different from when he first went viral over the summer. Here’s what you should know.  Pesto is beginning to molt and lose his infamous downy feathers. CREDIT: Sea Life Melbourne Aquarium/Olivia Hill. Alex Frank Who is Pesto? The juvenile King penguin was born at the aquarium in January 2024. His arrival was quite exciting for the aquarium, since no other King penguins chicks parched last year. Pesto is also the only King penguin that has hatched this year.  Pesto weighed less than half a pound when he was born, but has gained notoriety on social media for his huge size and fuzzy feathers. View this post on Instagram A post shared by RTÉ News (@rtenews) Why is Pesto so big in the first place? According to Sea Life Melbourne Aquarium Education Manager Olivia Hill, Pesto’s size is a combination of nature and nurture. “A combination of his parents’ genetics (his biological father Blake is one of Sea Life Melbourne’s largest birds) and excellent care from his foster parents, Tango and Hudson,” Hill tells Popular Science.  Get the Popular Science newsletter Breakthroughs, discoveries, and DIY tips sent every weekday. Email address Sign up Thank you! By signing up you agree to our Terms of Service and Privacy Policy. Pesto began to rapidly balloon in size. He’s made it up to 50 pounds as only a juvenile, while adult King penguins typically weigh 31 and 37 pounds. Pesto is the biggest chick that this aquarium has ever had. However, he won’t necessarily always be so large.  “He is dropping in weight now as his parents have stopped feeding him (as is typical at this stage as they are molting themselves) and will soon be a similar weight to all the other adults,” says Hill.  VIDEO CREDIT: Sea Life Melbourne Aquarium/Olivia Hill. VIDEO CREDIT: Sea Life Melbourne Aquarium/Olivia Hill. What is happening to pesto in this new stage? Pesto is growing his adult plumage. These new black, white, and yellow feathers are pushing out his old downy juvenile feathers in a process called molting. It usually occurs once a year for all penguin species and generally takes two to three weeks.  “Molting feathers will fall out over time during this process, but we observe the birds preening their feathers to remove the old ones using their beak and scratching with their toenails leading to some unique and often funny ‘hair styles’ during the process,” says Hill. “Pesto currently looks like he is wearing a brown feather boa over a white tuxedo shirt.” When he loses his feathers, he will look more like other King penguins. CREDIT: Sea Life Melbourne Aquarium/Olivia Hill. Alex Frank What will Pesto look like after molting? Eventually, he will look like other adult King penguins. Adult King penguins typically have an orange beak plate on the sides of their beaks. The juveniles have a dark brown or black beak plate. However, there is usually very little difference in their plumage, making them difficult to tell apart in the wild.  [Related: African penguins may tell each other apart by the spots in their plumage.] “We will be able to tell Pesto apart by this dark beak plate for the next year or so until he molts as an adult for the first time (November 2025) he will then shed his black beak plate and grow an orange beak plate, signifying he is an adult,” says Hill. “Then the only way to tell him apart from all the other birds will be by his wing band (241 – Brown Orange Black).” How can I see Pesto? He is currently on display at the aquarium, but also active on social media. The post Famously extra large penguin Pesto is molting appeared first on Popular Science.