Tank, who is not yet full grown, turned 55.
Griz, 12, will reach approximately 1,000 pounds and will live to be around 34 years old, said Nikki Lewis, the zoo's education director. Through both of the birthday celebrations, the affection that the animals had for her was obvious through Griz's talent of standing on his back legs, and Tank's nuzzling her and giving her a kiss.
Whitney Hahn, the administrative director, has been with the zoo since she was born; her parents are the owners. She said the animals in the zoo, which opened in 1966, are her extended family.
"We have our favorites," Hahn said, "but we have two new exhibits each year."
Hahn said Tank has been with the zoo since the tortoise was 25 years old. "We got him off a freighter from the Seychelles Islands, you can't do that anymore," Hahn said. "Tank should live to be around 100 years old."
To celebrate Griz's birthday, Lewis used an angel cake covered in honey. She offered pieces of the cake to the zoo visitors. She said simply throw the cake in the cage. Griz, the second largest type of bear, gobbled each bite of cake up and then searched around for more. Lewis allowed the smaller kids to throw Griz fruit.
Griz had a personal mailbox with "Letters to Griz" on the side. Hahn said he always gets mail and that he returns every letter.
"He has a column in KidsView Magazine that is based on letters to Griz," Hahn said.
She said there is a personal connection to all the animals.
"Tank is a real living being with feelings, a life and a history," Hahn said. "We tried to mate him, but nothing was produced."