An investigation has been launched at Blackpool Zoo following the death of an orangutan.
The male ape – called Beau – who was eight years old, was found dead in a moat surrounding his enclosure around lunchtime last Thursday.
A spokesman for the zoo said the animal died despite first aiders performing heart massage and mouth-to-mouth resuscitation.
He said: "We don't know exactly what happened.
"The keeper saw Beau in the water and got the other orangutans in before dashing to him.
"It was a frosty day but the ice had already broken.
"At the moment there is a full investigation being carried out."
Beau, who was hand-reared, was brought to Blackpool as a three-year-old in November 2002 from Twycross Zoo in the East Midlands.
He came to the resort following a double tragedy for the zoo as two orangutans, Hayley and Homer, died from an unexpected illnesses.
Zoo staff waited to see how Beau's relationship flourished with one of the zoo's female orangutans, before deciding he could stay in the resort for good.
Keepers confirmed he settled in well and he joined the zoo's three female orangutans – Vicky, her baby girl Summer and Cherie, his intended partner.
Blackpool Zoo is a selected partner in an international breeding programme for orangutans.
No accidents involving the moat had occurred since it was built 10 years ago, the zoo spokesman added.