Chris Pratt shares photos of rarely-seen son Jack in update ahead of change for family

It was an extra special, celebratory weekend for Chris Pratt and his family.

On Saturday, August 17, the Guardians of the Galaxy actor's eldest son Jack, who he shares with ex-wife Anna Faris , marked his 12th trip around the sun.

His birthday comes amid an even more special time for the Pratt family, as the doting dad is expecting his fourth child, his third with wife Katherine Schwarzenegger, who he married in 2019.

Though Chris has for the most part kept his kids largely out of the public eye, for Jack's special day, he made a rare exception and shared a round of photos of the birthday boy looking all grown up.

Giving insight into Jack's hobbies and personality, Chris shared several photos of Jack doting over different animals at a farm.

The first sees him feeding milk to a baby cow, and is followed by others of him looking over at sheep, petting a horse, and even carrying what appears to be a baby lamb.

"Happy Birthday to my wonderful son Jack," Chris wrote in his caption, adding: "I thank God every day for you sweet boy."

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He concluded: "You are so smart, hilarious, kind, thoughtful, trustworthy and tough. I love you so much kiddo. Twelve!? I honestly can't believe it."

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Fans were then quick to take to the comment section under the post with more birthday messages, with one writing: "Happy Birthday Jack! You are one cool kid," as others followed suit with: "Adorable photos," and: "Happy Birthday Jack! May God bless you with many more," as well as: "That's so sweet!"

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In addition to Jack, Chris is also a dad to daughters Lyla Maria, who celebrated her fourth birthday this month, and Eloise Christina, who turned two years old earlier this summer.

MORE: Chris Pratt thanks wife Katherine Schwarzenegger for 'stability' in their marriage on milestone 5th anniversary

© Jon Kopaloff

With only one year to go before Jack marks his milestone 13th birthday and officially becomes a teenager, his mom Anna recently opened up about how it has been to have a son go through puberty. "He told me that he thinks he has an armpit hair," she joked during an appearance on the Today Show, declaring: "It's happening."

And reflecting on how quickly he has grown up, she shared: "You miss it sometimes when you look at old photos," though added: "But I'm really loving this age."