The latest list of species close to extinction, a hundred of them, has been drawn up by the Zoological Society of London and the International Union for Conservation of Nature.
They include the pygmy three-toed sloth, the spoon-billed sandpiper and Tarzan's chameleon.
Prof Jonathan Baillie, director of conservation at the London Zoological Society and co-author of the report, said it is an ethical issue as well as about the future generation to preserve these species.
"It is our moral imperative to do so," he said. "We can't accept extinction on any level."
Dr Sarah Chan, deputy director of the Institute for Science, Ethics and Innovation at Manchester University, told the Today programme she believes it is difficult "to defend in a consistent way" the idea that all species have an equal right to exist.
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