Dads got in free with a paid ticket for their children. They then got to learn fun facts about fathers in the animal kingdom.
One dad says he likes the zoo just as much as his kids do. But he cares most about spending time with family on his special day.
"For either parent, when you get time set aside you know to recognize the parent. It's always nice. It's nice to be on the receiving end of that," said Christian Ritchie of Morton.
The crowds were a little busier than expected. More than 100 fathers and their families spent the day at the zoo.