Four decades after Kermit the Frog sang "It's not easy being green," amphibians worldwide know all too well how he felt. And it's not just difficult to be green; these are hard times for frogs of any color.

Frogs and toads today face a gauntlet of environmental threats, part of what the International Union for Conservation of Nature calls an "amphibian extinction crisis." Nearly one-third of Earth's 6,485 amphibian species are on the brink of extinction, according to California-based Save the Frogs.

One of the biggest factors in this has been the deadly chytrid fungus, which is blamed for declines or extinctions of more than 200 amphibian species. But the plight of frogs (and toads, which are technically frogs) is also compounded by many other dangers. Deforestation, wetland loss and climate change are wiping out their habitats; pollution and pesticides are permeating their skin; invasive species are stealing their food; and overharvesting for food and pets is draining their gene pools.

Save the Frogs Day is held annually on the last Saturday in April, organized by Save the Frogs and celebrated from Oregon to Ghana to Bangladesh. To honor the holiday, here's a look at frogs and toads from around the world, hinting at the beauty and diversity of Kermit's embattled brethren:

Chinese gliding frog, Polypedates dennysi (Photo: Martin Teschner/Flickr)

Common toad, Bufo bufo (Photo: Eddy Van 3000/Flickr)

Strawberry poison dart frog, Oophaga pumilio (Photo: ZUMA Press)

European tree frog, Hyla arborea; Note: Image consists of three exposures. (Photo: ZUMA Press)

Dumpy tree frog, Litoria caerulea (Photo: Wikimedia Commons)

Long-nosed horned frog, Megophrys nasuta (Photo: ZUMA Press)

Common frog with eggs, Rana temporaria (Photo: ZUMA Press)

Tree frog eggs (Photo: Geoff Gallice/Flickr)

Tadpole in metamorphosis (Photo: Dave Huth/Flickr)

Wallace's flying frog, Rhacophorus nigropalmatus (Photo: ZUMA Press)

Red-eyed tree frog, Agalychnis callidryas (Photo: Bill Bouton/Flickr)

Green toad, Bufo viridis (Photo: Umberto Salvagnin/Flickr)

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