Category Zoology

What is consciousness?

               The word consciousness in psychological term refers to the condition of alertness of the organism. The brain is the control centre of the body’s nervous system and plays a major role in man’s thinking, remembering, alertness and vice-versa. Unconsciousness refers to the state of sleeping. Between these two conditions one may have varying degrees of consciousness.

               In a condition of full consciousness the level of alertness will be very high. For example if someone is playing chess and wants to win, he would try to remain in a state of high alertness and deep concentration. Similarly the circus gymnasts would have to be very alert during their performances.

               If a person is dozing he is said to be in a state of lower level of consciousness. He would be regarded as unconscious if he falls asleep.

               These are different states of consciousness we come across in our normal day-to-day life. However, unconsciousness or sub-consciousness can also be produced by artificial means. A high state of consciousness can be produced with the help of some medicines which act as a stimulant to make person more active beyond his normal ability. Such medicines affect the central nervous system and produce such abnormal conditions. Caffeine in a strong coffee or tea can act as a powerful stimulant for some people. Too much alcohol can produce dozing effect and finally unconsciousness.

               Certain diseases have a marked impact on the level of consciousness. There are some mental diseases which can lower the consciousness of a person. Emotional disturbances also affect the state of alertness of an individual. Highly emotional people often get the feeling of depression.

               Today, scientists have developed several medicines and shock therapies which can control the level of consciousness. These methods are used for treating people with lower level of consciousness. However, these should be used only when prescribed by a physician. 

What is cholesterol?

          Cholesterol is an organic compound belonging to the steroid family and occurring either in a free state or as esters of fatty acid in practically all animal tissues. The molecular formula for cholesterol is. In a normal man it is about 0.3 percent of his average weight. It is the starting material from which the body produces bile acids, steroid hormones and pro-vitamin substances in the body. It is used by our body to help the digestive system as well.

          Cholesterol was discovered in 1812. Its name arises from its occurrences in gallstones derived from the Greek word chole-stereos-ol meaning bile-solid. The synthesis of cholesterol occurs in various tissues and organs particularly, the brain, liver and arteries.

          The increase in its quantity beyond a certain level can be harmful for our body. Excess of fat and cholesterol get deposited in the walls of arteries causing blockage and hardness thus obstructing the free flow of blood. Due to this, quantity of blood flowing in the arteries decreases and consequently the oxygen supply to vital parts of our body is also decreased. This condition is medically termed as arteriosclerosis. Small blood clots that would normally pass through blood vessels may get trapped by high cholesterol deposits.

          We know that coronary arteries play a vital role for the heart to function. They provide oxygen and carry blood to the heart. If a coronary artery gets blocked that particular part of the heart may stop functioning leading to a major heart attack which can even prove fatal.

          Cholesterol in blood can be controlled by a regulated diet. A high concentration of cholesterol is present in the foods of animal origin like meat, egg, butter etc. Doctors advise to avoid high-cholesterol foods by substituting unsaturated foods like fruits, vegetables, cereals and so on.

          Lowering cholesterol levels in the blood can help to reduce the risk of heart attacks. Several other measures can be taken to maintain the desirable cholesterol level. This includes giving up smoking, regular exercises, avoidance of overeating and fatty substances.

 

Why is the Asian koel unique?

 

          The Asian koel is better known by its voice than by its looks. The Asian koel stays almost completely atop trees and never comes down to ground. It is as big as a crow, but is leaner, with a longer tail. The famous koel song actually belongs entirely to the males. Females do not sing. Young male birds make harsh, crow-like sounds. But even the adults do not sing during winter.

          The Asian koel is also a brood parasite. It leaves its eggs, which are slightly smaller, but similar to crow’s eggs, to be raised in crow’s nests. These birds feed on berries, banyan and peepal figs and hairy caterpillars.

          Apart from the Indian sub-continent, these birds are also found in China and Southeast Asia. Earlier these birds were popularly raised in cages as pets. 

What are the features of the Indian cuckoo?

            The Indian cuckoo is a medium-sized bird found in forests and open woodlands. Its lower parts are grey in colour, while the upper parts show broad black bars throughout. The tail is also barred, but the tip is white and is preceded by a broader black band. The young birds have a dark face, but the top of their head and chin are contrastingly white in colour.

            The major diet of these birds includes hairy caterpillars and other insects. They are usually found on top of the upper leaf cover of trees, where they search for insects to prey upon. They may catch flying insects in the air, during which they may fly to lower heights too.

            One notable habit of these birds is to leave their eggs for some other bird to rise. They are therefore, called brood parasites. They’ll go to the nest of some other bird to lay their single egg. But before that, they will eat one egg from the host’s nest. The poor host bird will look after the cuckoo egg as its own.

            In India, drongos and crows are the common victims of the cuckoos’ brood parasitism. The Indian cuckoo is very common in India, Bangladesh, Bhutan, Nepal, Russia and Sri Lanka. 

What are the differences between the common myna and the bank myna?

The common myna and the bank myna are different in many ways. The common myna is comparatively larger with a brownish purple plumage. It has a black head. But the bank myna is smaller and bluish-grey in colour. It has some bare skin behind its eyes, which is brick red in colour. In the common myna, this skin is yellowish.

          The common myna is a bold and adventurous bird, mostly found in towns, villages and cultivation lands. They are courageous enough to enter even houses. But bank mynas are milder in their manner.

          The common mynas build nests in holes and they roost communally in tall grasses. They eat invertebrates, fruits, nectar from flowers and even garbage. But bank mynas dig holes in earthen banks of rivers and build their nest in them. Common mynas are found in almost all parts of India. Bank mynas tend to be concentrated in the northern and central regions of the country. 

What are the features of the wire-tailed swallow?

            The most notable feature of a wire-tailed swallow is its tail, as its name indicates. It has two long feathers extending from the tail, called tail streamers. This is a small, lean bird with a blue-and-black plumage all over. The cap of its head is chestnut coloured.

            These birds prefer living near water and human settlements. They are found in pairs or in small scattered groups. They do not like to live in colonies, but build their nests individually, choosing a particular territory. But they roost with other varieties of swallows in tall grasses and bushes.

            Insects are the major diet of these birds. They catch their preys in the air, using their superior flying skills. These birds are commonly found perching on wires.

            These birds are very common in India, except in the Northeastern states and in the extreme south. The birds in northern India have been observed migrating towards the southern regions during winter.