By John McDevitt

PHILADELPHIA (CBS) — There was a big splash for the birthday girl at Adventure Aquarium in Camden. Hundreds of people attended the party Friday for Button the Hippopotamus.

Keepers set up two cakes made from fruit and vegetables, and then it was party time. Adventure Aquarium’s two hungry hippos went right for them, the treats to celebrate Button’s birthday.

“Button just turned 21. Genny is actually 17, so they are pretty close in age,” said Adventure Aquarium senior biologist Mark Hacker. “But Button is a little older, a little bit smaller. She weighs about 3,100 pounds. Genny is 4,200 pounds.”

Justin and Jamie Marshbank of Westville, New Jersey love hippos, and couldn’t think of a better place to be for their first wedding anniversary.

(Reporter): Did you have a hippo themed wedding?

“No, but we did have a hippo cake topper,” Jamie said.

“Oh yeah, bride and groom hippos on top of the cake,” Justin explained.

They both have hippo tattoos. Justin has one on his wedding ring finger and Jamie on the inside of her arm.

So what is the attraction to hippos?

“Just their gracefulness, honestly, the size and how big they are. They just bounce around nice and easy like they are weightless.”

Birthday festivities will take place all weekend long at Adventure Aquarium.