Category Biology

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. 

               The twittering of birds usually produces a pleasant sensation, especially in the spring in countryside. Some birds produce very sweet sounds while others produce harsh and unpleasant sounds. Do you know why birds sing?

               The songs and calls are important methods of communication among birds. They sing to attract mates in the mating season, to warn other birds of any incoming danger from predators, and to establish their home territories or nesting area. The bird calls are usually distinctive and vary from species to species. This distinction helps the birds to identify the calls meant for them.

               Among all the species of the singing birds, the male bird is usually the singer. It sings to attract the female bird. The songs of nightingale produce the best musical effects and other birds do not match it in comparison. The mocking bird has its own harsh call but can imitate the songs of other birds. Crow has a very crude voice.

                Apart from singing, birds make other types of calls — call for sending alarm signals, for food or calling their parents, call in an aggressive or hostile mood etc. A few birds, such as pelicans and cormorants, are voiceless.

               The singing birds belong to the suborder oscines. Their vocal cords are located in a special box, the syrinx, at the base of the windpipe where it divides into two bronchi. The syrinx has a bony structure and forms a sound-box within which membranes vibrate when the bird exhales. This produces varying notes in the bird’s voice. The structure of syrinx varies from species to species and till now seven different types have been recognized.

               The songs of the birds have a pitch of about 4300 Hertz, which is above the highest note of a piano. Intensity of the calls of any single bird varies from the deep-pitched hoot of owls to the very high notes of small birds which are scarcely audible to the human ear. 

            There are several species of birds on earth which cannot fly because they stopped using their wings for flying many thousands of years ago. Perhaps neither the environment around them nor their living conditions required them to fly. Generally birds fly either to protect themselves from enemies or in search of food. These flightless birds either lived in places where there were no enemies to prey on them, or were so big that they could rely on their legs to carry them out of trouble. As a result, their wings almost fell into disuse and gradually they became flightless. Do you know which are the birds that cannot fly? 

   

 

        First of all we have the Penguins. They turned their wings into paddles or flippers. As a result they cannot fly but they are excellent swimmers. These birds mainly live in the southern hemisphere – mostly at the edge of Antarctica. 

 

 

 

            

 

                The Kiwis of New Zealand took to living by night, finding its food by smell and almost ceased flying. Gradually the bird became flightless. Also it almost stopped using its eyes and today it has very poor eyesight. Now these birds have small wings which are hidden by hair-like feathers that cover the body. 

Continue reading “Which birds cannot fly?”

               The most surprising fact about fishes is that you cannot hear them but, they can certainly hear you. Fishes are very well-equipped for hearing. They have a pair of ears. These ears do not have an outer projection as we have, but are simply tiny holes on either side of the head, leading to the inner ear. Since there is no external ear to direct the sound, these ears are probably not as effective as our own. But the fishes have other ways of picking up sounds of vibrations in the water. 

              Along each side of the fish’s body is a line of little holes or pores, which can also pick up vibrations and changes in pressure inside water and pass on the message to the brain. This line of pores is called the lateral line, and can be seen quite easily.

               By using this lateral line a fish can avoid all obstacles when it is extremely sensitive to pressure changes caused by the vibrations of another fish or some other objects. A fish’s lateral line contains sensory cells which provide the fish with all the information of events going on around it.

                   Some other teleost fishes such as catfish that lives in rather muddy water have barbells — long sensitive feelers on their mouths.

                   The fishes of the ‘carp’ family have tiny bones in the head which are linked to the swim bladder. The swim bladder keeps the fish upright in water and also acts as a sounding board which can pick up and magnify the tiniest vibrations, and then pass them along the bones directly to the inner ear.

                   These are the different mechanisms in the fishes by which they can even hear very feeble sounds.