Tricia the elephant turns 58 at Perth Zoo

Joe Hockey might think 150 is a ripe old age, but for one large Perth lady, reaching 58 is quite an achievement.

Tricia the elephant is content wallowing in her mud pit, sleeping under the stars and tucking into a special birthday cake made of bran and fruit.

But keeper Kirsty Carey said Tricia had started to show her age.

Just like humans, she's slowing down and has a little less hair.

She's also on her last set of teeth, with six sets being the limit for elephants throughout their lifetime.

"An elephant to live to this age is pretty special - she's one of the oldest ones in Australia," Ms Carey said.

"Every day is a blessing with her for sure."

Visitors sang to Tricia on Friday as she dug into her four-tiered cake.

And she didn't forget to bring a piece back to fellow elephant companion Permai, who showed her gratitude with birthday kisses.

But the real celebrations will happen on her actual birthday this Saturday when she'll get to show off her painting skills to the crowds and is given another cake.

Ms Carey said Tricia probably knows that it is her birthday because she isn't spoilt with such tasty treats everyday.

Tricia first arrived in Perth from Singapore in 1963 and is the zoo's longest resident.