Rolling on the Tundra: A Polar Bear Adventure

Question from Ashley, Kelsey, and Chris:

Is it hard for polar bears to catch seals?

From the scientists on Buggy One:

If the habitat of the polar bear is icy and snowy, polar bears are highly adapted to be able to sneak up on seals and capture them. Even as the best predator of the Arctic, polar bears only capture approximately one seal for every twenty attempts. If the habitat of the polar bears becomes warmer and there is no snow cover on the ice where seals can build snow caves, then the seals will be right on the ice and will be able to see the polar bears coming, thus avoiding capture. So, global warming will make it harder for polar bears to find and catch seals.

Question from Connor, Kyle, and Brent:

How much body fat and muscle does a typical polar bear have?

From the scientists on Buggy One:

This depends on the time of year. There is an annual cycle to their weight, and the weight variation is almost entirely due to fat. In March is when they have the least weight, then most of their weight is gained from March until July. During the time they are gaining, the polar bears are eating very fat seals. The bears then “cruise” on that weight for the rest of the year when the cycle begins again. Polar bears can double their body weight during the months they are feeding.

In regard to the fat/muscle ratio, it is hard for the scientists currently on Buggy One to quantify. There is a scientist who has conducted research in that area, Caryn Rode, but she is not with us on this trip.

The polar bears are very, very powerful with an incredible muscle structure used to run down and capture incredibly large seals. Obviously when they are in the period that they double their body weight, the added weight is fat. But, is difficult to give a pure ratio for the muscle/fat distribution because it is a cyclical relationship.

Question from Troy, Ty, and Aidan:

What do polar bears eat that make their liver so high in vitamin A content?

From the scientists on Buggy One:

As a carnivore that feeds largely on fish-eating carnivores, the polar bears ingest high volumes of Vitamin A. This is called biomagnification, and the information below describes this:

According to a website article written by Professor Anil Aggrawal, a Professor of Forensic Medicine at the Maulana Azad Medical College:

“Vitamin A originates in marine algae, and then passes up the food chain to reach the large carnivorous animals. Toxic levels of Vitamin A may accumulate in the livers of a wide range of creatures such as Polar bears, seals, porpoises, dolphins, sharks, whales, Arctic foxes and huskies.

Even a small meal of southern Australian seal liver, say 80 g, may produce illness in man. I may tell you that several foods are recommended as good sources of Vitamin A. Most of them contain well below the toxic levels of vitamin A, but one – Halibut liver oil – contains dangerously high amounts of Vitamin A, as you can see from the accompanying table.”

(The table is available on the Professor’s website.)

Resource for this information: http://members.tripod.com/~Prof_Anil_Aggrawal/poiso032.html

Question from Caldwell, Mac, Caleb, and Laura:

Why does a polar bear’s fur look white when it is really clear?

From the scientists on Buggy One:

Polar bear fur is clear, and lots of fur filaments held together look white in daylight (you can try this at home with a group of clear drinking straws — a single straw is easy to look through, but a whole group should appear to be white).