#726: A polar bear cannot be seen by an infrared camera, due to its transparent fur
Verdict: False (technically)
So this one is fun because 1. it's not that crazy when broken down, 2. the images are kind of funny, and 3. it's just overall neat-o. According to Now I Know, scientists were attempting to get a headcount on the number of polar bears in the Arctic, especially since they were hunted up through most of the 20th century. While their natural camouflage can make it tricky, obviously there are a number of devices we can and do use to capture images.
Turns out, due to the many layers of fur and fat trapping body heat very efficiently and "well below skin level," heat-detecting devices such as infrared are rendered all but completely useless. This is why I rated it this "Real Fact" as "false." The translucent nature of their fur (which is accurate) is not the reason they do not show up very well in infrared, but rather it's because the outer layers of their skin are about the same temperature as the air around them. Their face and breath can be reasonably detected, but according to the article, "that isn't enough to go on." Ultimately they've had to settle for tranquilizing and tagging each one individually (can't pay me enough to do that). Side note: Now I Know comes in newsletter form. I've been getting it for probably 5+ years now. Dan does great work so you should definitely consider signing up for it!
A few more tidbits about their ability to stay warm (in -40°C no less). They keep their internal body temperature at around 37°C with their distinct fur coat. It is made up of two main layers: a short and dense "underfur" beneath the skin and an outer layer made of translucent, long, coarse hairs. The translucent hair scatters light which is why it appears white to us.