Auckland Zoo staff are in mourning today for the loss of the little battler olive ridley turtle.

He washed up on a Hawke's Bay beach last week and by Friday was showing signs of getting better.

But in the early hours of Saturday morning, the turtle drew his last breath and it appears the brave patient was hiding the true extent of his suffering.

"It's always tough when they don't pull through," said zoo vet Melanie Leech.

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"But this was a very very sick turtle when it arrived, and based on its condition, the odds were unfortunately, stacked against him.

"While he appeared to be improving a little, he was clearly masking the full extent of its condition - a survival tactic animals often employ."

The rare olive ridley sea turtle spent a night at the National Aquarium of NZ in Napier last week before it was rushed to Auckland for further treatment.

The species usually lives in the Pacific Ocean's warm water, so there were immediate concerns for the animal's welfare when it washed up at Blackhead Beach in the middle of a Kiwi winter.

"It was really good that he came in to us, as we could make him more comfortable and do our best to give him the best possible chance," Leech said.

Zoo vets were waiting for the full results from the post mortem.