Maralee Nichols Enjoys Day at the Zoo with Her and Tristan Thompson's 6-Month-Old Son Theo

Maralee Nichols/Instagram

Maralee Nichols is enjoying introducing her baby boy to the world of wildlife!

On Wednesday, the model, 31, took her 6-month-old son Theo, whom she shares with Tristan Thompson, to the zoo for the first time and documented the sweet moment on Instagram.

In the photo, Nichols holds baby Theo as the mother-son duo look at the giraffes together at the San Diego Zoo.

"Can't believe my baby is 6 months old 🥲 Theo's first time at the zoo, he loved looking at all the animals 🦒," she captioned the snap.

Last month, Nichols celebrated her first Mother's Day and paid tribute to her son on social media.

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George Pimentel/Getty; maraleenichols/Instagram

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"Words cannot express how much I love you, being your mommy is my greatest blessing," she captioned the photo of herself holding Theo while wearing a floor-length dress. "You are my world."

"Happy Mother's Day to all of the amazing mothers out there," she added.

In February, Nichols revealed the special meaning behind her son's name.

"Theo, my little angel baby," Nichols said in a statement to PEOPLE at the time. "I named you Theo because it means, 'Gift from God.' "

"I had never been pregnant and had been told I might not be able to have children," she added. "I couldn't believe I was pregnant, when I saw you on the ultrasound and heard your little heartbeat I knew I would always protect you and keep you safe. I love you more than you'll ever know. You bring such joy and happiness into my life. My great blessing."

The birth certificate, obtained by PEOPLE, first revealed Theo's name. In a statement shared with PEOPLE from Nichols, she added that the athlete was not named on the birth certificate "because he was not present at Theo's birth."

The NBA player first confirmed he fathered the baby in January, writing on his Instagram Story, "I take full responsibility for my actions. Now that paternity has been established I look forward to amicably raising our son."

He continued, "I sincerely apologize to everyone I've hurt or disappointed throughout this ordeal both publicly and privately."

He also addressed Khloé Kardashian — with whom he shares daughter True, 4, and was dating when Nichols said the child was conceived. Thompson also has a 5-year-old son, Prince, with ex Jordan Craig.

"Khloé, you don't deserve this. You don't deserve the heartache and humiliation I have caused you," he wrote. "You don't deserve the way I have treated you over the years. My actions certainly have not lined up with the way I view you. I have the utmost respect and love for you. Regardless of what you may think. Again, I am so incredibly sorry."