SA zoo animals cool off with ice blocks

Orangutans are playing with garden hoses and sea lions feasting on fishy ice blocks at Adelaide Zoo as the state swelters through its third-consecutive 40-degree day.

Sprinklers, water misters and wading pools are also being used to help prevent heat stress, with the mercury set to reach up to 42 degrees on Friday.

But one-year-old baboon, Tomkay, isn't letting South Australia's worst December heatwave on record spoil his birthday.

"Like most toddlers, he's a mischievous little guy," says primate keeper Sophie Miller, who added that Tomkay would be chowing down on a cake filled with his favourite treats and helping to keep their minds' off the heat.

"He certainly keeps us on our toes and it's hard not to laugh watching his cheeky antics."