The National Zoo's giant panda cub is shown at 8 weeks old. He is growing and crawling, zookeepers said. (National Zoo)

Keepers at the National Zoo in Washington said the cutest black and white furball — their new giant panda cub — is gaining weight, crawling and, well, being playful like a baby.

Michael Brown-Palsgrove, the zoo’s Asia Trail curator, said the baby cub at first was mostly tucked under his mother Mei Xiang’s armpit or between her forepaws “to help keep him warm,” but the 8-week-old cub is growing and changing.

Brown-Palsgrove said the cub doesn’t nurse as much, and he’s “packing on the pounds.” With more pounds and his thick, woolly fur, the cub is able to better regulate his own body temperature.

Keepers said his favorite spot for sleeping is on the floor of the den next to his mama. The two will “playfully nibble at one another.”

The panda cub is reaching his milestones — crawling to exercise his muscles and improve his coordination, officials said. And when he’s about three months old, keepers expect he will take his first steps.

Mei Xiang’s 8-week old panda cub explored their indoor yard for a brief visit on Oct. 19. (Video: National Zoo)

Zoo officials said caretakers of the pandas have also noticed that Mei Xiang will go for her own snack and leave her cub in the den alone while she’s out in the large enclosure area where she eats bamboo.

Last week, zookeepers said she got one of her favorite foods — leaf eater biscuits (yum!) — from a rubber tub and took it back into the den for what keepers said was a “midnight snack.”

National Zoo’s female giant panda has a new ‘miracle’ cub

At times, mama panda takes her young cub out of the den and into the yard, which keepers call brief “field trips.” Zookeepers said that in the coming weeks they expect the field trips to explore the yard to become longer and more frequent.

The cub has been called a “miracle” because his mom at 22 was the oldest giant panda to give birth in the United States. Her baby was Washington’s first giant panda cub in five years.

The Asia Trail and the giant panda exhibit are temporarily closed to visitors because of scheduled repaving of walkways, officials said. The best way to see the panda is on the PandaCam.