Conservationists have identified 100 of the most threatened animals, plants and fungi on the planet.
The list has been drawn up by 8,000 scientists from the IUCN Species Survival Commission, including Professor Jonathan Baillie, the Zoological Society of London's Director of Conservation.
He has voiced the concern of the conservation movement that these species will be allowed to die out because they don’t benefit humanity in an obvious and direct way.
He said: "The donor community and conservation movement are leaning increasingly towards a 'what can nature do for us' approach, where species and wild habitats are valued and prioritised according to the services they provide for people.
“This has made it increasingly difficult for conservationists to protect the most threatened species on the planet.
“While the utilitarian value of nature is important conservation goes beyond this. Do these species have a right to survive or do we have a right to drive them to extinction?"
However, Dr Sarah Chan, deputy director of the Institute for Science, Ethics and Innovation at Manchester University, told the BBC Today programme that it’s hard to defend giving all species an equal right to exist.
She said: “The idea that all species have an equal right to exist is difficult to defend in a consistent way.
“So for example, when we say that all species have an equal right to exist, do we mean just all species that currently exist? What about species that have already become extinct?
“If we think species have an equal right to exist, we have an equal obligation to resurrect extinct species, we should bring back the dinosaurs and the dodos.”
She added: “One species we have successfully made extinct in the wild that I don’t think anybody thinks we should reintroduce is the smallpox virus.”
The 100 species, from 48 different countries are first in line to disappear completely if nothing is done to protect them.
The pygmy three-toed sloth (Bradypus pygmaeus) is one of the animals facing a bleak future. Escudo Island, 11 miles (17km) off the coast of Panama, is the only place in the world where these tiny sloths are found.
At half the size of their mainland cousins, and weighing roughly the same as a newborn baby, pygmy sloths are the smallest and slowest sloths in the world and remain critically endangered.
Similarly, the saola (Pseudoryx nghetinhensis) is one of the most threatened mammals in Southeast Asia. Known as the Asian unicorn because of its rarity, the population of these antelope may be down to just a few tens of individuals today.
In the UK, a small area in Wales is the only place in the world where the brightly coloured willow blister (Cryptomyces maximus) is found. Populations of the spore-shooting fungi are currently in decline, and a single catastrophic event could cause their total destruction.
Professor Baillie added: "If we believe these species are priceless it is time for the conservation community, government and industry to step up to the plate and show future generations that we value all life.''
A report, called Priceless or Worthless?, will be presented at the IUCN World Conservation Congress in South Korea this week.