SAN FRANCISCO – Two young reindeer lounging in their pen the Saturday before Thanksgiving — the day of their big holiday season premiere at the California Academy of Sciences in San Francisco — were taking a break after eating lunch.

They were lying around, but children outside the pen were fascinated, pointing, calling out to the deer and doubtlessly wondering why they weren’t training. After all, the reindeer’s biggest day of the year was only about a month away.

The academy employee supervising the scene said they were saving their energy, being from Northern Europe, which is very cold.

Uh-huh. That’s why they save their energy.

Everyone knows why a reindeer needs a lot of extra juice. They’re really saving it for the long trip on Dec. 24.

The academy just opened its annual “‘Tis the Season for Science” program. Besides the young reindeer jolly old Saint Nick lent the academy, there’s festive decor, public programs about visiting animals, music, dance and magic performances, cookie decorating and seasonal photo ops.

There’s also snow periodically falling inside the big presentation space in the center of the museum. The snowflakes were a big hit Saturday, if running, screaming, dancing children trying to catch snow on their tongues were a good indicator.  

There are also lots of spots for photo ops and more practical winter wonderland information, like how animals adapt to climate change.

Of course, the best thing about going to the Academy of Sciences during the holidays is having an excuse to do something really cool and tell oneself it’s educational for the kids. It is, but it’s also a lot of fun.

The four-legged holiday visitors are just outside the academy’s eastern end. Baby camels are scheduled to make an appearance Dec. 6, followed by baby yaks on Dec. 20. 

They all have a place in holiday lore, but the academy makes sure visitors get some scientific facts as well. 

Signs outside the pen explain these two reindeer are only seven months old and recently weaned from mom. They’re tiny but tough, one sign says, and are built for the cold. From birth, reindeer, camels and yaks are adapted to withstand the elements.

Reindeer quickly develop insulation for arctic (North Pole?) life, camels grow thick fur to protect them from chilly desert nights, and yak calves’ sport shaggy coats for high Himalayan mountains. 

“As climate change alters and reduces habitats, these species — and many others — face new challenges. Humans can help these resilient young animals thrive by protecting and regenerating ecosystems,” a sign said.

Then there’s of course, the year-round penguin exhibit, which is a favorite, judging by the crowds gathered around the viewing window. Unlike the other animals brought in to celebrate the holidays, penguins are typically from the planet’s (very) deep south, where it’s very cold.

“Every year the academy catches the holiday bug with ‘Tis the Season for Science,’ more than a month of wintry festivities with a special academy science twist,” academy executive director Scott Sampson said in an email. “This year we are stepping up the action with visits by pairs of live baby reindeer, camels, and yaks for two weeks each to explore winter survival adaptations and other unique features of these adorable creatures.

“The museum also is buzzing with other fun and educational activities, including falling snow inside our piazza; seasonal science experiments (think dry ice); and music, dance, and magic performances from over a dozen diverse troupes,” Sampson said. 

And, of course, there’s the old favorites, including the world-class Steinhart Aquarium starring Claude the albino alligator, who was very active this day.  

The lush, four-story Osher Rainforest dome was full of more than 1,600 butterflies, birds, fish, plants (and tropical humidity – wear layers) and the Morrison Planetarium was mind-boggling, as usual. (Tom Hanks narrating a trip through the universe in “Passport to the Universe” is worth waiting in line for 20-30 minutes).

The California Academy of Sciences is at 55 Music Concourse Drive in San Francisco. 

Public hours are 9:30 a.m. to 5 p.m. Monday through Saturday and 11 a.m. to 5 p.m. Sundays. Thursday NightLife is from 6 to 10 p.m. The museum is closed Dec. 4 for a private event. 

For more information, go to www.calacademy.org.