A list of the top ten mammals most reliant on zoos for their survival has been compilied by the British and Irish Association of Zoos and Aquariums (BIAZA).
The list highlights the work done by zoos to safeguard the future of the animals, in the wild as well as in captivity, and in the decreasing opportunities for the mammals to flourish unaided in their natural habitat.
The Amur leopard is one of the most endangered large cats in the world, and there are currently only 50 remaining in the wild.
Originating from China, Russia and Korea, they are held in zoos in Yorkshire, Colchester, Edinburgh and Twycross.
Blue-eyed black lemur
The Blue-eyed black lemur is critically endangered, and lives in the wild in a very restricted area within northwest Madagascar. Only a very small total population remains.
They can be seen in Banham Zoo and Edinburgh Zoo.
The Scimitar-horned oryx, once found in Tunisia, Morocco and Sengal is now extinct in the wild and completely dependent on captive breeding for survival.
Conservation and breeding efforts mean they live in a number of Zoos across the UK and Ireland, including Dublin, Chessington, Chester, and Whipsnade.
The Sumatran tiger, from Indonesia, is critically endangered due to hunting and loss of habitat. There are now only between 300 and 400 Sumatran tigers remaining in the wild.
They live in captivity in a number of zoos and wildlife sanctuary's across the UK, including Belfast, Chessington, Edinburgh and London.
San Martin titi monkey
The San Martin titi monkey is not kept in zoos, but BIAZA zoos work as partners in the only conservation project working to protect the species.
The monkey is found in Peru, and is critically endangered.
Grevy's zebra has experienced one of the largest reductions of range and numbers of any African mammal. They live in dwindling numbers in the wild in Ethiopia, Kenya and possibly South Sudan.
The live in Banham Zoo, West Midlands Safari Park, Chessington Zoo, Edinburgh Zoo and Woburn Safari park, among others, in captivity.
Livingstone's fruit bat
The Livingstone's fruit bat is one of the largest bat species in the world. Less than 1,100 of the species remain in the wild on the island of Comoros, off the coast of northern Mozambique.
It lives in captivity in the Durrell Wildlife Conservation Trust, Bristol Zoo Gardens and Chester Zoo.
The Pied tamarin is found in the wild in only a very small region of the Brazilian rainforest.
It lives in captivity in Birmingham Nature Centre, Chester Zoo, London Zoo, Paignton Zoo, Newquay Zoo and the Shaldon Wildlife Trust, and others.
The White-naped mangabey is one of the most endangered primates in the world. Only 15% of their original habitat remains in Ghana, and Cote d'Ivoire.
It lives in captivity in Flamingo Land Park and Zoo in north Yorkshire, and London Zoo.
Western lowland gorilla
The Western lowland gorilla remains under threat of extinction from specialist hunting and increasing loss of habitat.
It is found in the wild in ever decreasing numbers in Angola, Cameroon, Central African Republic, Congo, Equatorial, Guinea, Gabon and Nigeria.
It lives in captivity in zoos and wildlife gardens in Belfast, Blackpool, Chessington, London, Paignton, Twycross and Bristol.