Biodiversity Study Sounds an Extinction Alert (for Things with Spines)

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Biodiversity researchers warn that 20 percent of vertebrate species are threatened with extinction, largely because of human damage to habitats. But conservation efforts, they say, are effective.

If a creature has a spine and walks, flies, swims, or crawls, it may be in serious trouble.

Some 20 percent of all vertebrate species on Earth are threatened by extinction, according to a newly published survey - a study the research team involved says is the most exhaustive to date on biodiversity among vertebrates.

The losses are due largely to human encroachment on habitat, over- fishing and over-hunting, as well as the arrival of invasive species in habitats …