From birth to now, he's gained about 800 pounds.

Hint: it's a species that hails from Africa, where its name derives from.

This koala mom's joey is named "Burra" which means 'Big Fella.'

The Steller's Sea Eagle is the heaviest eagle species in the world.

Having a new giraffe calf at the San Diego Zoo is always an exciting event.

Learn how handlers make sure their penguins maintain a healthy diet.

How zookeepers target train animals and what it's used for.

Learn how handlers make sure their penguins maintain a healthy diet.

The 1-day-old giraffe passed her first health exam with flying colors.

Zookeepers and doctors meet a new giraffe calf for the first time.

Get an up-close look at what it's like to train a Steller's Sea Eagle, the heaviest eagle species in the world.

Check in with a female joey and see what her life is like and what's in store as she grows up.

Meet Tony and his mom Funani at the San Diego Zoo's river hippopotamus exhibit and learn all about this young calf's development.

Zookeepers work to keep a routine weigh-in as quick as possible so they're not separated from mom for too long.

Weighing 2,000 pounds and with characteristic mustache-shaped horns forming what's known as a "boss," this is one tough animal you wouldn't want to mess with.

This koala mom's joey is named "Burra" which means 'Big Fella.'

This hippo calf is actually famous the world over for his "hippo ballet."

Target training is used to get the meerkats to stand on a scale so they can be weighed.

Sometimes the koala joeys play switcheroo on their moms.

Get a behind-the-scenes look at how African penguins are cared for at Little Rock Zoo.

The Steller's Sea Eagle is the heaviest eagle species in the world.

Why touch is very important in this early stage of life for these cubs.

Having a new giraffe calf at the San Diego Zoo is always an exciting event.

Zookeepers work to keep a routine weigh-in as quick as possible so they're not separated from mom for too long.