Last week marked the 5th appearance of Endangered Species Day. Although young as annual commemoration days go, Endangered Species Day draws attention to an age-old countdown that has been accelerated by human development at a frightening rate. In the U.S. alone, more than 500 species have gone extinct since the Mayflower docked.

Nearly 2,000 plants and animal species are listed under the Endangered Species Act, granting them varying levels of protection. From American Alligator to Mountain Zebra, from San Diego Ambrosia to Suisun Thistle, too many flora and fauna are facing the end of the line due to habitat loss, invasive species, pollution, and more—and these are only the ones we know about.

National Geographic photographer Joel Sartore features 68 endangered species in his book Rare: Portraits of America’s Endangered Species. Several of those also tried out their acting chops, as evidenced in this video:

Scientists estimate that 10–50 million species inhabit the Earth. Of these, a mere 1.7 million have been classified, and far fewer are studied to the extent that conclusions can be drawn as to the outlook of their long-term prospects.

The U.S. Fish and Wildlife Service explains just why it’s worth saving species:

All living things are part of a complex, often delicately balanced network called the biosphere. … No one knows how the extinction of organisms will affect the other members of its ecosystem, but the removal of a single species can set off a chain reaction affecting many others.

The Endangered Species Act is one of the U.S.’s strongest environmental laws—and one that Earthjustice uses extensively to protect our wildlife. The ESA has had everything from cameos to starring roles throughout Earthjustice’s work, most recently to protect spring-run Chinook salmon, Hawaiian petrel, and the Pacific fisher.

Meanwhile, out in the Gulf of Mexico, the Deepwater Horizon oil spill is menacing endangered sea turtles and North Atlantic bluefin tuna—as well as the brown pelican, a recent ESA alumni and success story.

The ESA can be confusing, as laws are occasionally wont to be. Take a look at Earthjustice’s handy Understanding the Endangered Species Act for a clear, birds-eye view of the Act. And, if the Rare video left you thinking film production was as serene and stately as the video’s final cut, the backstage view tells a slightly different story:

More Reads:

• Spotlight on Rare (photos), Neatorama.com
• World’s smallest water lily saved from extinction, Scientific American
• New Species Found in "Lost World" (photos), National Geographic