Event has been going on since late 1960s. "It is a day that transcends culture, language, and tradition," Google said, explaining the significance of its series of Google doodles celebrating our planet.
In Friday’s doodle, the ubiquitous Google logo morphs to depict, in turn, a polar bear in the tundra, a red fox in the forest, an elephant in the grasslands, a tortoise in the desert and an octopus in the ocean - with a different one appearing each time one visits the site’s homepage.
"The vastness of the Earth’s diversity makes it an intimidating topic, but in the end I chose to highlight the Earth’s five major biomes,” doodler Sophie Diao said in a blog post. She further added, “On a day like this, we remember and celebrate our home in this great and stunning ecosystem."