An endangered Bolivian squirrel monkey has been stolen from a zoo during a night-time raid.
The monkey, named SpongeBob, is still missing after thieves broke into Chessington World of Adventures, near London, early on Monday morning.
Zookeepers found two of the fences surrounding the Monkey & Bird Garden had been cut.
Another nine of the monkeys - which are known to be territorial - were either still inside or close by, but SpongeBob has not been found and is presumed stolen.
Sonia Freeman, head of mammals at the zoo, said the two-year-old breeding male, affectionately known as Bob, had only been at Chessington for three months.
She said: "He had been especially selected through the European Endangered Species Programme to be introduced into the group of females as a breeding male, and he was successfully integrating with the group.
"We are devastated that he is gone as he is a much-loved member of the zoo with his cheeky personality."
She added: "He is still a wild animal and not a pet. If he is not looked after properly he can become very upset. He is also on a very specialised diet and he will be very unhappy and stressed at being separated from his group."
Detective Constable David Burton, from Kingston Police CID Department, said officers were investigating the incident.
He said: "We have concerns for the safety and welfare of this endangered squirrel monkey. If seen, we recommend you do not approach him as he may be in distress due to being in an unknown environment."