PICTURES: Como Zoo's Galapagos tortoises celebrate 25th birthday

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Courtesy of Como Zoo.

Marco and Irwin, two Galapagos tortoises at the Como Zoo, turned 25 years young on Saturday. The celebration in their honor included banners, party hats for their shells and a delicious cake.

The tortoises munched down on a homemade cake with the encouragement of a cheering crowd.

According to the zoo, the cake was designed especially for their diet. The ingredients list included: papaya, pear, mandarin oranges, apples, strawberries, edible flowers, pineapple, cantaloupe, cucumber, collard greens and even asparagus "candles."

Galapagos Tortoise Fun Facts:

Marco and Irwin are native to the Galapagos Islands, and are still growing. The average Galapagos tortoise lives to be about 150 years old, and weigh 475 lbs. Marco and Irwin are 240 lbs and 280 lbs, respectively. They are the largest species of tortoise currently living.

They have a bit of length to grow into as well, and will eventually be about four feet long.

The Galapagos Islands, known for wildlife-viewing, are some of the most protected areas in the world. The Galapagos tortoise helped Charles Darwin develop his theory of evolution, and rumor has it he adopted one as a pet who eventually outlived him.

Marco and Irwin have some large shells to fill, as the oldest living Galapagos tortoise lived to be 152 years old.

Galapagos tortoises also nap for up to 16 hours a day, and survive up to a year without food or water.

On their native islands, Darwin's finch and some mockingbird species have developed unique relationships with the tortoises. According to Como Zoo, tortoises will stretch out, leaving their limbs and necks exposed so the birds can pluck ticks and bugs off of them.

To help the species or learn more, check out the Galapagos Conservation Trust.