Ursus maritimus…that’s the Latin name of the majestic polar bear, the largest carnivore that lives on land. You’ll find polar bears in northern Greenland, Norway, Siberia, and Canada.
Polar bears are among the largest land mammals on Earth. Male bears can weigh 1,700 pounds and stand eight to ten feet tall. Female polar bears weigh about 1,000 pounds and are six to eight feet tall.
Their name means “sea bear,” which is quite appropriate. Polar bears spend most of their lives in, on, or around water. Polar bears are excellent swimmers. But they’d rather stay on top of the ice that covers the Arctic Circle most of the year.
Why do they spend so much time on the frigid Arctic ice? The Arctic waters and ice floes are where their favorite food—seals—can be found.
Seals can be tricky to catch, though, so polar bears must hunt with great stealth and patience. They will also occasionally eat other animals, including walruses and dead whales. Fortunately, their white coloring helps them blend in with their icy surroundings.
So how did polar bears that live in a snowy-white world come to have white fur? Believe it or not, their hair isn’t actually white!
Their long outer hairs, which protect their soft, thick undercoat, are mostly hollow and transparent. The thinner hairs of their undercoat are also clear.
So why do polar bears look white? The air spaces in the hairs scatter light of all colors. For that reason, we look at polar bears and see the color white.
Some scientists believe the polar bear was once a close relative to the brown bear. They think that, over time, polar bears moved to the Arctic. There, they adapted to their surroundings. Slowly, they developed fur that would help them blend in with the Arctic ice.
Not all polar bears look white, though. Have you ever seen a polar bear in a zoo? If so, you may have noticed that its fur can appear almost green.
Scientists discovered that algae from the pond waters in the bears’ enclosures made the bears turn green. They learned these algae were found not on the surface of the hairs but inside the hollow hairs!
Standards: NGSS.LS1.A, NGSS.LS1.C, NGSS.LS1.D, NGSS.LS2.C, NGSS.LS2.D, CCRA.L.3, CCRA.L.6, CCRA.R.1, CCRA.R.2, CCRA.R.4, CCRA.R.10, CCRA.W.3, CCRA.L.1, CCRA.L.2, CCRA.SL.1, CCRA.SL.2