Standing as tall as 10 feet on their hind legs and weighing from 800 to 1,300 pounds for males, polar bears are as imposing as they are majestic. They’re the world’s largest land carnivores, don’t fear humans, and have no natural predators — another way of saying that Ursus maritimus is at the top of the food chain. Though they're sadly considered a vulnerable species, with just 22,000 to 31,000 left in the wild, their conservation status is a result of climate change reducing their sea ice habitat rather than direct threats from other (non-human) animals.
Polar bears aren't the only apex predators, of course; they’re joined on that intimidating list by bald eagles, saltwater crocodiles, snow leopards, orcas, and other creatures. Whether humans count as apex predators now is a point of some debate: We certainly dominate the ecosystem, but we eat lower down on the food chain than other apex predators usually do. And as long as bears, sharks, hippos, and other imposing species continue to do their thing, humans will continue to have natural predators, even if most of us are usually lucky enough to avoid being preyed upon.
It isn't just sunlight that makes its way into that translucent fur. When polar bears find themselves in warmer climates — most often in zoos or wildlife sanctuaries — algae can grow in their hair and turn it green. The effect is completely harmless (not to mention oddly adorable) and easily reversible with a salt-solution-infused bath.