11 September 2012 Last updated at 13:47

In pictures: 100 most threatened species

The Zoological Society of London and the International Union for Conservation of Nature (IUCN) have released a new list of the species closest to extinction. The Tarzan chameleon lives on Madagascar, inhabiting a range of about 10 sq km. Its forest home has been shrinking fast due to human activities such as logging.

The Santa Catarina's guinea pig also has a restricted geographical distribution - of about 40,000 sq m - on the small island of Moleques do Sul in Brazil. People have free access to the island, which has made conservationists concerned about the potential for hunting.

Diceros sumatrensis Save the Rhino International

With a population size thought to number just 250 mature individuals, the Sumatran rhino is classified as Critically Endangered by the definitive Red List. The major human threat to the species comes from hunting, driven by demand for the supposedly medicinal properties of rhino horns and other body parts.

Edwards's pheasant is native to the damp mountain forests of central Vietnam, but its habitat has been denuded by herbicide sprayed during the Vietnam war, along with clearance for agriculture. The bird has not been seen sighted since 2000, and there are suggestions it may already be extinct in the wild.

Scaturiginichthys vermeilipinnis Adam Kerezsy

The striking red-finned blue-eye fish is found only in a complex of freshwater springs in north-east Australia. The species is being threatened by the introduced mosquito fish and by the practice of draining water from a natural basin associated with the springs.

Hibiscadelphus woodii is a species of small tree known only from the Kalalau Valley on Kauai - one of the Hawaiian Islands. It was discovered in 1991 and is under pressure from invasive plants and feral goats.

Science & Environment

In pictures: 100 most threatened species

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