Saturday, August 18, 2012

Can Animals identify different Colors?

            We know that animals can see things like us. But can they distinguish between different colors like human beings? To find an answer to this question, scientists have conducted a number of experiments on different animals like cats, dogs, apes and bees.

            Experimentally, it has been found that dogs cannot distinguish between different colors. Some dogs were given eatables of different colors but the variation in colors had no affecting them. This has proved that dogs cannot identify different colors. Some experiments of this type were found to be color blind.

            Besides man, ape is the only mammal, which can differentiate between different colors. All other mammals are color blind.

            The honey bees also have this exceptional characteristic. They can differentiate between different colors. However, they cannot identify the red color. Red looks like black to them. It is on the basis of identification of colors that these bees are attracted towards the flowers of different colors from which they collect honey. The honey bees are also capable of seeing the ultraviolet rays tat even human beings cannot see.

A honey bee can see ultraviolet rays but it fail to identify red color

            To test their power of color vision, the bees were shown two cards- blue and red. A little syrup was placed on the blue care, whereas the red card was without it. The honey bees gathered on the blue card. Then the blue card, without any syrup on it was kept at a different place. The bees reached there as well. This proved that they could distinguish between different colors.

            Even birds can differentiate between different colors. The color of the male birds is more attractive than those of the females. These colors are used to the attract the female. It has been observed that birds can identify all the colors of the rainbow.

            Generally animals have no need to distinguish between colors because most of them hunt by night and do not depend on color. However, they have a greater power of smell and as such their color blindness does not handicap them.

Friday, August 17, 2012

Our Universe - The Sun

            The sun is one of the stars in the Milky Way. It looks bigger than other stars because it is the closest star to the earth. However, it is smaller than some other stars. Betelgeuse, a red giant star, is 800 times bigger than the sun.

The sun is a huge mass of gases

            The sun lies about 150 million km. from the earth. Its diameter is about 1,40,000 km. i.e., 109 times the earth’s diameter. Its gravitation is 28 times more than the gravitation of the earth.
Parts of the Sun

            The sun lies at a distance of about 32,000 light years form the centre of the galaxy. It takes the sun about 225 million years to complete one revolution around the center of the galaxy with a speed of 250 km. per second. This period is called cosmic year. The sun, like the earth, and, therefore, can rotate at varying speeds at different latitudes. It rotates once on its axis in 24-25 days at the poles and in 34-37 days at the equator.

            The sun is composed of about 75% hydrogen and almost 25% helium. It may be called a big hydrogen bomb because it release huge amount of heat and light as a result of nuclear fusion. The sun is directly
Responsible for all life on earth. It provides the earth with all of its light, heat and energy.
            The glowing surface of the sun which we see is called photosphere. It has a temperature of about 6000 degree centigrade while the temperature of the core is 15,000,000 centigrade Celsius.

            The glowing flames constantly arising from the photosphere are called solar prominences which rise up to a height of 1,000,000 km.

            The dark spots noticed on the surface of the sun are called sunspots. They are cooler than the surrounding area. The life span of sunspots varies from a few hours to many weeks. Larger sunspots may have temperatures up to 4000-5000 degree Celsius. Some of them are made of many folded layers larger than our earth’s size.

            When sunspots persist for longer periods, they cause solar flares and high solar prominences which create upheavals in the ionosphere resulting with disturbances in our radio communications.

Wednesday, August 15, 2012

How did different Plants get their Names?

            Ever since the evolution of languages, different plants and trees have been given names to distinguish one plant form the other. The nomenclature is essential for general use for a gardener’s catalogue and is often very interesting and hence worth-knowing.

The names of all the trees have interesting origins 

            Some names have simply been borrowed form other languages, while some others take the name of the places of their origin. Some plants have been named according to their shapes and colors while others owe their names to some unique features. Some may have come after the names of their discoverers. Over the years even the names have undergone changes. The origin of names of some important plants and trees are discussed below.

            The pine tree got its name from the Latin word pinus that means a point. The spruce tree should really be called the Prussia tree because it was long thought to be a native of Prussia. The name gradually got corrupted to spruce.
            A buttercup is a flower, which has the shape of a cup and the color of butter. Lady’s mantle was the name given when ladies wore collars that were plated with serrated edges like the leaves of the plant. Honeysuckle has flowers rich in nectar and is, therefore, popular with bees collecting substance for making honey.

            The magnolia has been named after Pierre Magnol of France who was a professor of botany. The cypress is called so because it was first brought from the island of Cyprus. In Madagascar, there is a tree called, The Travelers Tree. It has large, fan-shaped leaves that catch the rainwater and the passing travelers sometimes quench their thirst with this water.

            The barber plant has been named so because the natives of orient used to rub its leaves on their faces to check the beard from growing. The names dandelion comes from the French words dent die lion because the leaves of this plant resemble the teeth of a lion. Thyme comes form the Latin word thymus that means to sacrifice; the Romans used to burn this plant on their altars.

            A plant called self-heal got its name because it was thought to have a healing effect on wounds. Since carpenters are supposed to cut wood with sharp tools more often than other people. This plant is also called carpenter’s herb. The farm workers used this plant as a bandage and hence it has two other names also- hook-heal and sickle-wart.

            The names of many plants often carry a warning. Deadly nightshade is a poisonous plant that grows among the ruins supposedly haunted by ghosts and evil spirits.

Which Fish is called the King of Fishes?

            Just as lion is called the king of beasts, the same way shark can be called the king of fishes. It is the fastest and the most dangerous fish in the sea. It is also huge in size, ranging from 1 foot to over 50 feet. Another reason for calling it the king is that it belongs to one of the oldest group of creatures alive in the world today. Some fossils of sharks are believed to be as old s 250,000,000 years.

Shark is the king of fishes

            A shark is a saltwater fish that belongs to the class Chondrichthyes. Its skeleton is made up of cartilage rather than bones. Its skin is covered with many small scales, which are like sandpaper. There are about 400 species of sharks in the world.

            The dogfish shark grows up to around 3 feet in length. It feeds on small fish and invertebrates. The whale shark, the largest of all fish, can reach up to 50 feet in length. It is the least dangerous one. These sharks have many razor-sharp teeth. The great white shark, the greediest monster, swallows its prey as a whole. The remains of big animals, such as seals, dolphins and smaller sharks have been found in its stomach.

            A shark will eat almost anything found in the sea, from the tinniest sort of sea creatures to other sharks, turtles, seals or dolphins. They have been known to swim up rivers and attack crocodiles, horses and elephants that might have waded into the water. They are also found to attack people swimming in the sea. In the pursuit of their prey, they can move very fast. They follow the ships to feed on the waste food thrown overboard from the kitchens of the ships. Some sharks live and hunt alone, while others prefer to roam the seas in packs.

            Most of the sea beaches in Australia and South Africa are protected form sharks by iron-nets and electric barriers, for the safety of the swimmers.

            Sharks are caught in large numbers every year. Their meat is very nutritious and cheap, and can quite delicious if properly cooked. Their skin is used for binding books, covering boxes, and for making bags and shoes.

            The most beautiful shark is the mako shark. It is snow white underneath and brilliant blue on the top. It is very fast and ferocious and a strong fisher when caught alive.

Saturday, August 11, 2012

Which is the Birds prey?

            The birds, which feed on other animals, are called the birds of prey. They catch and feed on animals that are usually smaller than them. They may catch their prey anywhere on the ground, in air or in water. But not all birds bother to the flesh of dead animals. Do you know which the birds of prey are?

Eagle, a bird of prey

            The common birds of prey are- buzzards, eagles, falcons, harriers, hawks, kestrels, vultures and woodpeckers. Owls also catch smaller animals and feed on the out they are put in a different category. Most of the birds of prey are brown-colored. They are found in all the continents except Antarctica. They kill they prey with their strong sharp talons, and pluck and tear the flesh with their narrow, hooked beaks. These birds normally swallow huge chunks of food and regurgitate the pellets of indigestible matter.

            The birds of prey attack in two ways. Kestrel hunts by hovering over open ground and then plunging down on its prey before it can escape. Falcon stoops or dives its head first at its prey and catches it in its talons. Eagles are powerful and soaring birds of prey.

            Some eagles hide in a tree and wait for their prey to wander into a clearing. Carrion eaters soar on outstretched wings at considerable heights for hour’s together ad peering down for animals already dead or the ones about to die. In contrast to it the small birds of prey like the sparrow hawk dash at high speed through trees to sprig surprise on a small creature. The birds of prey also kill with their feet. Although some use the beak for the purpose, yet the sharp, curved talons of the feet are the main killing weapons. The rear and inner talons are usually larger than the middle or outer one. These help the birds to exert a strong pincer grip on the prey.

            The birds of prey hunt a variety of animals such as rabbits, hares, grouses, fishes and other smaller birds.

How do Seeds of the Plants get dispersed?

            There are a number of ways in which plants differ from animals but one of the most pronounced differences is that animals can move and plants cannot. Plants remain static at one place even though they grow vertically or horizontally depending on their growth pattern. But then how do these plants spread their seeds to grow at different places? It is interesting to note that nature helps them in this activity and this process is termed as dispersal of seeds.

Dispersal of seeds by Animal

            Dispersion of seeds is carried out basically by four main agents namely air, water, birds and animals. Some plants also carry out their own dispersion.

            When the plants themselves carry out the dispersal, the process is called dehiscence. In dehiscence or dispersion by explosion, a seed-containing structure such as a pod, bursts shooting the seeds into the air. These seeds land up at a distance depending upon the weight of the seed and the force with which they are thrown. Some of the plants that disperse their seeds in this manner include plants of the pea, mustard, and balsam family.

            Air is also an effective dispersing agent for the seeds. Lightweight seeds fly form one place to another along with the wind. Some grass seeds have been detected at heights of more than a thousand meters. Lightweight orchid seeds are carried away by air to great distances form their parent plants. Seeds of some plants, such as dandelion and cattail, have puffy hair that helps them float through the air and land up elsewhere. The seeds of maple, ash and box elder have wing-like structures to move like small helicopters in the wind and thus get dispersed.

Dispersal of seeds by Wind

            For dispersal by water, the seeds must be waterproof and able to float. Mangroves and coconuts have floating seeds with tough coats.

            Birds and animals disperse seeds in a variety of ways. Some seeds have burrs or hooks, which get attached to the fur or the tails of the animals. They ca be carried to great distances traveled by the animals before falling off. Some seeds such as mistletoe are enclosed in sticky barriers. When a bird or animal eats these berries, the seeds get stuck to its feet, mouth or body. Some seeds are enclosed in juicy, tasty fruits, which are consumed by birds, animals, and human beings. These seeds remain unaffected by the digestive system and are passed out of the body, as in the faeces. The seeds of grapes, mulberry, pe3ars etc. are dispersed this way. Grazing animals such as cattle and sheep often disperse the clover and cereal crop seeds.

Dispersal of seeds by Water

            Human beings often disperse seeds by throwing away apple cores, peach pits and other inedible seeds form juicy fruits. People carry seeds to great distances unknowingly when they carry them in fruits and other food items in long journeys.

            Apart from these main agents of dispersion of seeds, there are other irregular agents that help in this process.

How do the Fishes Smell Things?

            There are two pairs of nostrils in fish. Each nostril has two openings, which are called pits. One opening is in the front, and the other directly behind it. A small flap separates the two pits. However, the location of the nostrils may vary from species to species.

Fishes find their way back home by smelling

            When fish is under water, a current of water enters form the front pit and comes out through the rear one. As the water flows inside, it stimulates the sense cells, which enables the fish to catch the smell. Many fishes have a keen sense of smell. They can detect even the faintest smells.

            In fact, the sense of smell may help a fish to find its way home. Some fish could distinguish between the water of two creeks through smell. But if their noses are plugged, they get lost. To prove this fact some researchers had performed certain experiments. In one experiment, a large number of salmon fish were taken out of their home stream. Half of them had their noses plugged; the other half did not. The fishes with plugged noses got lost and the rest half could find their way back home again. Anglers use peculiar scented fish-food to attract them.

             Apart from the sense of smell, the fishes have other sensory perceptions also such as the sense of touch, taste hearing and sight.