Species are going extinct all over the world: Scientists believe that Earth is losing between 200 and 2,000 species every year. That number is squishy, partly because there are so many species for which they lack good data—particularly those living in the oceans, which are difficult to track but still critically important to ecosystems and livelihoods. Even the most comprehensive evaluation of extinction risk—the international Red List of Threatened Species—has only spotty data for many species around the globe.