Category Science

            It seems strange but true that the first species of birds originally evolved from reptiles about 140 million years ago. The evolution of birds followed the same course as that of any other species — in a slow and gradual process. They originated from reptiles to develop to its present form passing through different stages. The first bird was called archaeopteryx which was of the size of a crow. The existence of this bird is supported by fossil records. But what are the distinct features that classified it as a bird? 

            Though in appearance it was quite like a reptile and had teeth like a lizard and a long bony tail, yet in many other ways it had different characteristics from that of a reptile. Its head was balanced upon a long, thin and probably flexible neck. It had feathers instead of scales. These distinct features made it a bird and not a reptile and that is why archaeopteryx came to be known as the first bird on earth.

            It was different from the modern day birds in many other important ways. It could not fly properly for any considerable distance as it was not able to flap its wings very hard and probably used them for gliding as well as sailing through the air. It had a small poorly developed breast-bone. It had claws on its wings and was a warm-blooded bird. 

Continue reading “How did the first bird evolve?”

            Zebra is a member of the horse family. But as compared to other members of this family it stands apart because of its striped coat. Each animal has its own special pattern of stripes.

            Today we have three species of zebra that have survived over the ages. The most commonly found is Equus quagga – known either as the common zebra or as the plains zebra. It inhabits eastern and southern Africa – south of Ethiopia. The other species is Equus grevy which is found in Somalia.

            It is the largest of all zebra species and has numerous thin stripes and very large ears. The third surviving zebra species is called the mountain zebra or Equus zebra. It has numerous narrow stripes and is found in the mountains of Namibia (South-West Africa) and Angola. At one time, there existed a species called quagga which had stripes only on its head but is now extinct.

            Since all the species have parallel black or brown stripes on white background, it is not off the mark to assume that the stripes must in some way be helpful for these grazing animals. Although a number of theories have been advanced to explain this phenomenon, none gives a very convincing explanation. According to one theory, the stripes create a ‘dazzle pattern’ and thus help the zebra to hide from its enemies by blending with the ‘shadow-sunlight’ patterns where it lives. Since lion is its main enemy, this physical characteristic helps to protect it. Some other researchers have suggested that the stripes are disruptive, and create confusion in singling out an individual zebra when they are bunched together due to the overlapping of their outlines. This helps in protecting them as a lion finds it difficult to single out a potential victim.

            Zebras are grazing animals; some roam around open grassy plains whereas others live in rough mountains. They usually live in small bands. They are noted fighter, and it is difficult to tame or train them.

            The gestation period of different zebras varies from 300 to 390 days. Usually one young is born at a time although twins are also a possibility. 

          There is a peculiar species of sea-fish that keeps its eggs in its mouth. It is the catfish found in the Atlantic Ocean off the east coast of America. The most surprising fact about it is that instead of the female, the male takes on the responsibility of looking after the future family. After the eggs are laid and fertilized, the male quickly puts them into his mouth. They completely fill its mouth and prevent it from eating. It carries them around for a month. During this period it is unable to take its food, and lives off the food reserves built up before the spawning. Moreover, his motherly role does not end even after the hatching of eggs. For two more weeks, the youngsters swim into his mouth to hide when any danger threatens them. 

               There are seven kinds of fishes which are called catfish and are found in eastern and central North America. Some species, like the flathead catfish and blue catfish, can even weigh more than 45 kg. The catfishes live near the bottom of slow-moving rivers and lakes. They have four pairs of barbels around their mouth. These barbels look like the whiskers of a cat and hence they are called catfishes. The barbels are quite sensitive and help the catfish feel its way around and find food.

          The electric catfish is one variety which uses electrical discharges to stun and capture other fishes. Its electric organs lie just under the skin and cover its body and part of the tail. A large catfish may even produce a current of 350 volts.

          Another kind of catfish called Wels catfish grows to huge sizes in muddy-bottomed lakes in central Europe. Some specimens grow up to 9 feet in length and some others compete with Arapaima which is claimed to be the largest fresh water fish in the world. 

Scorpions are small insect-like creatures that belong to the class arachnids. They live in the tropical areas of the world. They hide themselves in dark places, under logs or stones, and wait for their prey. Their fossil history goes back to 400 million years, and it is believed that they must have been among the earliest of land living arthropods. Today about 600 species of scorpions are known to man.

Scorpions are quite ferocious animals, and hence they are forced to a solitary life. In the houses, they find safe hiding places in shoes, beds and even under the carpets. If threatened or disturbed, they do not hesitate to sting over and over again. However, the severity of the sting varies from species to species. Although their sting is very painful, yet normally it’s not fatal. However, some tropical species like the Egyptian scorpion, leiurus, can be very dangerous and even cause death. The poison acts by paralyzing the nerves of the heart and chest muscles. In the United States and Mexico more people die from scorpion stings than from snake bites.

They are usually black or yellowish in appearance ranging from 1.3 to 17.5 cm in length. The body of a scorpion can be divided into two major parts. The first part is the cephalothorax which consists of the head and the chest. The hind part is the long abdomen, which tapers to form a tail. The tail has a stinger at the tip. The scorpions have a pair of claws and four pairs of legs. The claws are used to capture their prey using the large pincers. Scorpions use the stings which is located at the tip of its tail, to stun or kill their prey.

Scorpions are nocturnal animals, i.e. active mainly at night. They feed mainly on insects, spiders and other small animals. The female scorpions bear their young alive. The newly-born ones stay with the mother for several days, clinging to her body with their tiny pincers.

The sting is a curved organ at the end of its tail and two glands at the base give out a poison that flows from two pores. Most of the people fear the scorpion because of its sting. On the other hand, most of the scorpions do not sting human beings unless troubled, and prefer to retreat rather than fight. 

                    Lizards are mostly found in warm countries. They are reptiles with a dry scaly skin and a long tail. There are 3,000 kinds of lizards. But the focus of our discussion is the lizard that squirts blood from its eyes. It is called Horned Toad or Horned Lizard and is commonly found in Mexico and other parts of North America. A number of theories have been advanced to explain this strange phenomenon. Although this lizard squirts blood very rarely yet how does it do so and why? It has been observed that on such occasions the lizard is able to increase the blood pressure in its head, rupture the membranes of tiny blood vessels in its eyes and squirt drops of blood up to a distance of several inches. According to the biologists this action is a defence mechanism. When squirted into the eyes of an attacker, its blood acts as an irritant, and diverts the attention of the attacker.

                    The Horned Lizard belongs to Iguanidae family. There are about 14 species of this lizard. It is characterized by dagger-like head spines or horns. Its typical features include a flattened oval body and pointed fringe, and scales along the sides of the body. The length of the lizard ranges from 3 to 5 inches.

                    They usually live in desert or semi desert sandy areas. They feed on insects, mainly the ants. They conceal themselves by wriggling sideways until the entire body except the head, is covered. They are often kept as pets but seldom live long in captivity.

            The kingdom of animals has always been a source of fun, amusement and entertainment for man. We often discover very amazing and interesting features and characteristics in some animals that are peculiar and unique to those animals only. Now when we say there exists a type of bear which wears spectacles, it sounds amazing. But is it true?

            The truth is that the visual appearance of its face gives the spectator an impression that it has put on a pair of glasses. In reality, lines of lighter fur of white colour encircle its eyes and these circular markings around the eyes look like spectacles from a distance. 

            This ‘spectacled bear’ is found in tropical South America. It is very small in size. An interesting pattern is made on its facial area when a creamy yellow snout with fur of the same colour runs down from the nose and sometimes it makes a ring around the eyes and then cross the nose. These rings are the so-called ‘glasses’. It is also called the Andean bear. Some of them have only the bottom half of their glasses, whereas, some have the eye-rings so thick that they completely fill the face.

            Although there is only one species of the spectacled bear, Tremarctos ornatus, there are different kinds of facial markings within the same species. Though all bears can climb trees, the spectacled bear is particularly expert at clambering through the branches to feed on leaves, fruits and nuts.

             The ‘spectacled bear’ is the smallest among the bears. The adult is up to 64 cms 2 feet at the shoulders, 120 to 180 cms (4-6 feet) in total length, with about a 7 cm long (3 inch) tail. The colour of its shaggy coat varies from dark brown to black. It weighs less than 135 kg. Although it may feed on small mammals, deer, guanacos and vicunas, its diet mainly consists of fruits and leaves. It usually lives in cool mountain forests.

            Litters of one to three cubs have been born in captivity after a gestation period of 8-8 months.