Google is marking by highlighting a few of the more extreme living things we share the planet with.
Google's Monday Doodle features an animated slideshow exploring six different endangered organisms from different Earth elevations, some of which have only recently been discovered by humans. The Doodle also includes fun facts about the organisms and offers the curious the chance to learn more about them in search.
Earth Day, which is observed on Monday this year, was founded in 1970 in response to an oil spill that occurred a year earlier off California's coast, spewing more than 3 million gallons of oil and killing more than 10,000 seabirds, dolphins, seals and sea lions. The annual one-day celebration aims to raise awareness of environmental issues, with events around the globe promoting recycling, pollution reduction and care for the planet.
The theme of this year's Earth Day is Protect Our Species and is intended to draw attention to the rapid global destruction and reduction of the world's plant and wildlife populations. EarthDay.org links the declines to human-driven phenomena such as climate change, deforestation, habitat loss, poaching, unsustainable agriculture, pollution and pesticides.
"All living things have an intrinsic value, and each plays a unique role in the complex web of life," EarthDay.org said in a statement. "We must work together to protect endangered and threatened species.
"If we do not act now, extinction may be humanity's most enduring legacy."
The organisms featured in this year's Doodle include the Wandering Albatross, which has the largest wingspan of any living bird; the Coastal Redwood, the tallest tree in the world; the Paedophryne Amauensis, the smallest frog and vertebrate; the Amazon Water Lily, among the world's largest aquatic plants; the Coelacanth; a rare fish that at 107 million years old is one of the world's oldest living species; and the Deep Cave Springtail, an eyeless insect that's among the world's deepest-dwelling terrestrial creatures.
Some of these species were discovered in the past decade, and one thought extinct for 66 million years was rediscovered 80 years ago.
Google also shared some of the most searched for questions about wildlife, including how many teeth do snails have, how do octopuses mate, and is a gorilla a monkey. Do you know the answer to these questions? Have fun learning about our often delicate neighbors on the planet Earth.
Originally published April 21, 4 a.m. PT.