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 retrospect, after the behavior evolved and the eye migration began. As I said, this is not established truth, but still ...

Why are blue whales so big?

It is certainly an advantage to be enormous when you live in a cold environment. Whales live, as we know, in the water, where heat is lost much faster than on land (think of how much quicker you begin to freeze in water that is 68°F than on land when the air temperature is 68°F!). As if that were not enough, the blue whale developed a migration pattern in which it migrates to the polar regions, where it is extremely cold, to eat. Large animals lose less heat because the ratio of surface (skin) to volume (body) is small — body heat radiates out through the skin. Thanks to its size, the blue whale can spend less energy on maintaining body heat. Whales are also special in that they have extra insulation (blubber) to cover them and keep them warm. Blubber also serves as a food supply during the winter months when they are in the warmer waters to mate and give birth to cubs, and where food is not nearly as plentiful.

Another benefit of being enormous is that the risk of being killed by a predator is lower (but, unfortunately, this has not applied with humans, who have made the whales almost extinct in their search of the whales' coveted oil).

Undeniably, it can also be an advantage to be large when it comes to fighting and to finding a partner, but we know very little about this when it comes to blue whales.

Since it is important for animals to produce offspring as soon as possible, the early whales that grew the most quickly probably benefited in this area, leading the species to become larger.

... every day a blue whale poops 3 percent of its weight? That's over 5 tons a day!

... the blue whale is the animal with the largest heart, while the sperm whale is considered to have the largest brain?

A prerequisite for the blue whale and other large whales to develop was that there was plenty of food available. Belonging to this family are the baleen whales — that is to say, those that evolution equipped with a new kind of feeding apparatus, baleen (instead of teeth), with which they can filter large amounts of krill and other food from large volumes of water. By starting to migrate to the polar regions, where krill and other species exist in huge quantities, they were given access to a very rich food source, as there was less competition.

THEORIES OF BEACHED WHALES

The reasons that individual whales or entire pods become stranded are unclear, and frequently debated. One possibility is that one whale, perhaps the dominant whale, simply loses its orientation and swims off in the wrong direction. The other whales in the pack then follow because they are inclined to follow the choices of their leader.

Another theory is that the whales that reside in deep water react to the so-called rush when they feel the seabed against their abdomens, which could lead them to land.

None of these explanations is particularly convincing. Therefore, it has more recently been accepted that the different sounds that are on the same wavelength as a whale's own communication (underwater explosions, ship machinery, or sonar) could be interfering with the whale's orientation. There are observations that could indicate that this is the case, but it has yet to be proven. Still, after major naval exercises where sonar was used, mass-stranding of whales has been observed.

Which is tallest — the giraffe or the blue whale?

It is a bit difficult to find the dimensions of exactly how tall a blue whale is, but it's still easy to crown a victor. The blue whale, with its near-100-foot length, is easily the longest, but tallest it is not. A blue whale is estimated to be between 10 and 12 feet high, while a giraffe can be nearly 20 feet tall.

THE LARGEST AND SMALLEST AMONG MAMMALS

The largest and heaviest mammal is the blue whale, Balaenoptera musculus. The length of an adult blue whale is a maximum of about 108 feet, with a corresponding weight of just over 180 tons. The whales in the southern hemisphere are larger than those in the northern hemisphere.

The largest land mammal is the African savannah elephant, Loxodonta africana. Males are larger than females. They can live to be 70 years old and they continue to grow throughout life. They can grow up to 13 feet tall (at the shoulders) and can weigh up to 7 tons.

The smallest sea mammal is Commerson's dolphin, Cephalorhynchus commersonii. Commerson's dolphins range in length from 4 to 5.5 feet and can weigh up to 19 pounds.

On land, the smallest are likely the shrews of the genera Sorex,Microsorex, and Suncus, with possibly the whitetoothed pygmy shrew, Suncus etruscus (Etruscan pygmy shrew), or the lesser pygmy mouse, Sorex minutissimus, being the absolute smallest. Kitti's hog-nosed bat (or bumblebee bat), Craseonycteris thonglongyai, is also very small, with a size close to that of a bumblebee.

Penguins

STREAMLINED

Penguins vary dramatically in size and weight, although they are all quite similar in body shape and appearance. They are usually blue-black or blue-gray on the top, while the underside is white. Penguins have a dense plumage that consists of three layers of short feathers. They have a streamlined body, and wings are reduced to strong, narrow, and rigid "fins" with which they can move through the water at high speed. Their feet and legs are short and sharp, and their legs are placed far back on the body. When penguins swim, they use their tail feathers like rudders. Features that distinguish one species from another — tufts, lines, bands, or other markings — are usually on the head and upper chest. Under the chest is usually plain gray or brown.

A LAYER OF FAT DOES THE TRICK

Penguins are primarily adapted to live in a cool climate; they can exist in tropical regions, but only in connection with the cold ocean currents (such as the Humboldt Current or the Benguela and Agulhas Currents). To keep warm in a cold environment, penguins have a very thick, dense, and waterproof plumage. Moreover, they have a proper fat layer inside the skin, and a system of blood vessels acts as a kind of heat-exchanger in the legs and the wings.

... most penguin litters consist of two eggs? Only the emperor penguin and king penguin lay a single egg. Incubation is 32–63 days, depending on the species. The egg is kept at a temperature of 102°F in the skin flap, although the ambient temperature may be –40°F with wind blowing at a velocity of 90 miles per hour.

... male king penguins have the ability to store food in their stomachs for up to three weeks? Since the males sometimes brood the eggs for many days before the females take over, they have developed the ability to store food for a long time while keeping it fairly fresh.

... emperor penguins can dive down to a depth of over 1,800 feet and stay underwater for up to 20 minutes?

... typical penguins swim at speeds of 3–6 miles per hour, and stay underwater for an average of 2.5 minutes, but can be underwater for up to 5 minutes?

What is the difference between a frog and a toad?

The species in the order of anurans, Anura, are called either frogs or toads.

ADOPT A TOAD!

Toads and other amphibians have a difficult life in environments near cities. Allowing parts of a garden to grow a little wilder creates places where toads can roam. Toads eat worms, snails, and ants. In addition, they gladly feast on mosquitoes and other night-flying insects that are attracted to light sources.

TIPS

A small garden lantern on the ground — preferably with a light flat stone over it — could become an excellent smorgasbord for toads. Additionally, an accessible compost pile is an ideal wintering place for these animals.

And while you're at it, an undisturbed pile of twigs is an excellent wintering spot for hedgehogs, and they also like it when you allow the garden to grow a little wild.

... a bee walks by moving the first and third legs on one side of the body simultaneously with the second leg of the other side? This means that the middle legs are never used together. This mechanism is true of nearly all insects — that is, all six-legged creatures.

... the edible snail is actually born with a small shell house, a "mini house," which it then carries through life? In the shell, you can see different numbers of calcium lines that tell the snail's age. Each line corresponds to one year. The edible snail generally lives 8–10 years, but specimens up to 37 years old have been found.

... an earthworm can be over 10 years old? But in the wild it is usually not more than 2 years old.

... leeches only need to eat (i.e., drink blood) once a year? But when they eat, they eat quite a bit. They suck in an amount of blood equivalent to 5–10 times their own weight!

... there are over 60 species of ladybugs in Sweden alone? Worldwide, there are around 5,000 different species of ladybugs.

... the moth with the largest wingspan is the nocturnal Thysania agrippina? The largest known specimen measured 12 inches (more than the height of a standard piece of paper). This moth can be found from Brazil to the southern United States.

... the moth with the largest wing surface in the world is the Hercules moth, Coscinocera hercules? The largest known specimen has a wing area of over 100 square inches (larger than a standard sheet of paper). Hercules moths are found in tropical Australia and New Guinea.

... of all the world's birds, the magnificent frigatebird has the largest wing surface relative to body weight? All birds have very light bones, but frigatebird bones are extraordinarily light.

How long can a viper get?

The Swedish record held by a viper was from Härjedalen (Kappruet) and is 41 inches, which is very unusual. The general rule in Sweden would be that a female viper would not exceed 31 inches, and a male 30 inches, but even these lengths are now rare.

MONOTREME FACTS

-> Monotremes are the only mammals that lay eggs. Typical mammalian traits of monotremes are that they have fur, they have three ossicles in the middle ear, and they have a single bone in the lower jaw.

-> Today's monotremes consist of two families with a total of three genera and five species.

-> The platypus, Ornithorhynchus anatinus, is the only member of the family Ornithorhynchidae.

-> The echidna family, Tachyglossidae, consists of two genera: short-beaked echidnas, Tachyglossus, with one species, and long-beaked echidnas, Zaglossus, with three species.