HOW THEY LOOK!

COLORS

Are zebras white with black stripes or black with white stripes?

For a long time it was thought that zebras were white with black stripes, but current embryological research shows that the opposite is true.

All zebras have a dark base that is black, brown, or beige, depending on the species. Over this dark base run white or light gray stripes, which may run together across the abdomen, creating a cohesive field of stripes. Even the tail and mane are colored, and there is a fine tuft of hair at the bottom of the tail.

SILVER, RED, OR BLACK

It is not uncommon to find different color variations within a species. For example there are three color variations of red fox, namely, red, cross, and black.

The black fox is jet black and can appear to be a shining silver color when its topcoat is laced with white tips. The cross fox has a black band along the back and another one across the shoulders, forming a cross. And the red fox is, of course, red.

Genetic expression of these variants is determined by four different genes, which interact in various combinations. Extreme groups consist of the red and silver, while the cross fox is an intermediate form. Although not common, black foxes are quite natural.

In addition to the three basic variants, there may be different color variations in natural fox populations.

FIREFOX

One of these is that which Linnaeus called "firefox," and it has a black-tipped tail and an ashen stomach, like a red fox that walked through a fire. Linnaeus first classified this as a separate species, Canis alopex, but later reconsidered. In Fauna Suecica Linnaeus wrote: C. vulpes ferrugineus, which means rust- or generally dark-colored.

Other unusual color variants of foxes include a white coat with black-tipped ears or a white ring around the neck.

What color would a chameleon be on a chessboard?

One thing we can immediately conclude is that the chameleon would not be checked in black and white. There are about 80 different species of chameleon worldwide, and no species behaves exactly the same as any other. The color change, caused by contraction or expansion of microscopic pigment cells in the skin, is primarily due to light, temperature, or the animal's state of mind. Color change, therefore, does not depend on the background. In general, chameleons get brighter at higher temperatures; thus, they become lighter at night and bolder in strong light. When a chameleon is scared, it will become mostly grayish-brown. There are numerous factors that affect a chameleon's color at any given time, and each species generally has a rather limited color range.

Why are polar bears white?

Polar bears have white fur to blend in with their surroundings and, underneath, they have black skin to more effectively absorb heat. Each hair is hollow to provide optimum insulation against cold. (This is believed to be the reason that the coat looks black when photographed with ultraviolet light. UV light is evidently absorbed by the hollow strands. This effect also may make the coat appear yellowish.) The hair conducts heat radiation to the black skin and helps the animal to absorb as much heat as possible. Add a 4-inch layer of pure fat and you will understand how polar bears keep from freezing. In fact, they must move slowly to prevent overheating in the Arctic, where the temperature does not exceed 50°F in the summer and drops to — 40°F in the winter. In contrast to many other animals, the polar bear's fur does not change in the summer, but remains thick and white year round.

THE CLIMATE IS THREATENING THE POLAR BEAR

Rising temperatures forced many animals to draw closer to the north and south poles. As the temperature rises, it melts a greater part of their natural habitats away. There are two major threats to polar bears that are directly caused by climate change. First, their hunting grounds disappear as the ice melts; they depend on ice for accessing their food. With the help of its excellent sense of smell and excellent underwater vision, the polar bear hunts among floes on the shores. It can wait for hours at one of the seals' breathing holes. When the seal surfaces, the bear strikes. It kills the seal with a single bite of the head or with a blow from its massive, heavy frame. The polar bear depends on ice to hunt. In summer, when the ice pulls north, the polar bear must set off hundreds of miles to get food. The second threat comes when the ice disappears and the polar bear is unable to swim back to shore and drowns. And polar bears can swim far. They have been seen swimming 100 miles from land!

POLAR BEAR FACTS

The polar bear has a second, transparent eyelid (nictitating membrane) that acts as a pair of swimming goggles and protects its eyes while swimming.

The bear's maximum speed when running on land is about 30 miles per hour. Its walking speed is about 3 miles per hour.

A polar bear can live to be 25–30 years old in the wild, and about 40 years old in captivity.

Unlike other bears, polar bears are not naturally afraid of humans. If they are very hungry, they will attack us.

Some polar bears hibernate in snow caves, while others are active year round. Pregnant females always dig down in a cave to hibernate (October — April).

SIZE AND SHAPE

Why are flat fish flat?

There are several different kinds of "flat" fish. Rays have become flat probably as a combined result of their food being on the ground, their mouths facing downward, and their need to bury themselves for protection. The free-swimming mantas probably have bottom-dwelling ancestors.

As regards the so-called flatfish, there is a theory that states that they are flat because the fry (young fish) is so heavy that it sinks to the bottom, resulting in the second eye having moved to the face-up side — the side that was not down in the sand. To me, this sounds more like an ex post construction. Alternatively, one can speculate whether a behavior that is present in another fish may have been the cause. This fish lies on its side on the sandy bottom and plays dead. When another fish — a small mouthful — swims up to see the "dead" fish, it jumps and snaps up its prize! This fish is Nimbochromis livingstonii and lives in Lake Malawi in Africa. A mottled appearance makes it look like a decaying fish in a half-dissolved state.

This would also explain why flatfish larvae became heavier, as the ground is where they would need to be. The heavy fry thus evolved in...