Pixelation to represent endangered species counts
In 2008, the World Wildlife Fund ran a campaign that used pixelation to represent the number of animals left for endangered species. One pixel represents an animal, so an image appears more pixelated when there are fewer animals left. Imgur user JJSmooth44 recently used more recent numbers to show the images for 22 species.
Seven endangered species that could (almost) fit in a single train carriage
Some species are so close to extinction, that every remaining member can fit on a New York subway carriage (if they squeeze).