Archive for November, 2012

Why does not a spider get caught in its own web?

Spider 

Spiders build their webs to trap flies and other insects for food.  An insect is unable to escape once it has become caught in the spider’s web.  The more the insect struggles, the more it becomes entangled in the sticky threads. A spider’s silk is strong enough that most insects cannot break through it.

A web-spinning spider does not become caught in its own web.  When walking across the web, it grasps the silk threads with special hooked claw on each foot.  The spider also secretes an oily liquid onto its legs and feet that prevent the sticky silk from sticking to its body. – Dick Rogers

Why are piranha fish so dangerous?

Piranha

In South American rivers swims one of the world’s most dangerous fish—the piranha.  This savage fish is only ten or so inches long, but its teeth are so sharp and its jaws are so strong, it can chop a piece of flesh from an animal or a human as neatly as a razor. Piranhas often travel in schools of several hundred.

Their diet usually consists of other fish.  But if an animal happens to be in the water near a school of hungry piranhas, they attack and devour it instantly.  Animals as bit as a horse have been eaten down to a bare skeleton in only a few minutes. – Dick Rogers

What are a cow’s horns made of?

Cow’s Horn

A cow’s horns are made up mostly of special growth of touch skin material called “keratin.”  The nails on your fingers and toes are made of this materials.  So are the claws and hooves of animals.  The horns keep growing throughout the animal’s life.

Since cattle can use their horns as weapons, they are sometimes dehorned to make them safer for cattlemen to handle.  The cattle are also less likely to injure each other.  Some breeds do not grow horns.  Cattle born without horns, or whose horns are removed, and called “polled” cattle. – Dick Rogers

How many eyes does a fly have?

Fly

If you have ever tried to swat a fly, you know that this pesky insect seems to be able to see n all directions.  The fly can see any movement you make because it has five eyes—two large eyes and three tiny ones.  You can easily see the two big eyes that cover most of the fly’s head.

These big eyes are called “compound eyes,” and are made up of many little facets packed closely together.  On top of the fly’s head are three tiny simple eyes, called “ocelli,” arranged n a neat triangle.  With its five eyes watching, the fly is usually able to dodge your swatter. – Dick Rogers

What was a unicorn?

Unicorn

Old Greek and Roman myths tell of a strange beast with the head and body of a horse, the tail of a lion, and the beard of a goat.  It was called a “unicorn.”  A unicorn had a single long, twisted horn sticking out of its forehead.  Those who drank from a cup made of a unicorn’s horn were said to be protected from poison.

The idea of unicorns may have started with the tales told by early travelers—tales which probably described the rhinoceros or the oryx, a long-horned antelope. The tales grew more marvelous each time they were told.  – Dick Rogers

Why fish don’t sink?

Fish

A fish, with its bones and scales, is heavier than the water it displaces. Under normal circumstances, it would tend to sink.  But most bony fishes have a balloon-like sac inside their bodies called an “air bladder” that acts as a float to keep them from sinking.  The air bladder fills up with some of the oxygen dissolved in the fish’s blood.

Some fish, such as pike and catfish gulp air at the surface of the water to fill their air bladders.  A shark has no air bladder to buoy it up.  It must constantly be swimming in order to keep from sinking. – Dick Rogers

How does coral grow?

Coral

Beneath the surface of the sea lie coral formations of many shapes and colors.  The formations may look like branching trees tinted green or lavender, lacy sea fans, or even like tiny organ pipes.  Coral is formed by millions of tiny sea animals called “coral polyps.”  Coral polyps look much like little flowers.

They wave food into their mouths with a circle of tiny tentacles.  Young coral polyps attach themselves to older ones and build limy, cup-like skeletons around their soft bodies.  When the polyps die, their hard skeletons remain as part of the growing coral formations. – Dick Rogers

Why do camels have humps?

Camel

People used to think that the camel’s hump was a storage place for water. But the hump on its back is mostly fat.  Camel’s live in the desert, and they often have to go a long time without food. When food is scarce on long desert treks, the fat in the hump provides energy for the animal.

When the camel has not eaten for a few days, its hump gets smaller.  After the camel has had a few days’ rest and some foods, its hump becomes firm and plump again.  The camel must drink water.  But once it drinks, it can go for days without drinking again. – Dick Rogers

How do bats fly in the dark?

Bat

A bat can fly in total darkness and yet never bump into anything.  The bat has a built-in radar system.  As it flies through the dark, it utters a twittering sound that is too high-pitched for us to hear.  Echoes of these sounds bounce back from any nearby object.

But listening to these echoes with its big ears, the bat is able to avoid obstacles in its path.  The bat also uses echoes to locate the mosquitoes and other insects if catches and eats.  It isn’t true that bats are blind.  They do depend mainly on their keen ears, but most bats can see in daylight. – Dick Rogers

Can a lizard break off its tail?

Lizard

Have you ever seen an animal drop off its tail?  Grass snakes and certain other lizards can leave their tails behind to save their lives.  Most lizards have tails longer than their bodies.  If an enemy catches the lizard by the tail, the lizard quickly breaks off its tail, which continues to wiggle for a few minutes.

While the twitching tail holds the attention of the would-be attacker, the lizard makes a safe getaway.  The lizard does not seem to miss its tail, and it soon grows a new one to replace it.  But the new tail is never as long as the original one.– Dick Rogers