Category Zoology

How do plants protect themselves from frost?

            There are over 350,000 kinds of plants in the world. All these continue to struggle to survive against storms, rains, sun and snow. There are some which die due to cold in winters, although before dying their seeds are spread on the ground so that in the autumn they can give birth to new plants. However, there are some plants which are able to protect themselves against winter.

            These plants are able to protect themselves against winter frost by a special method. They spread their leaves and flatten them against the ground. The warmth in the soil enters their leaves and the plant is protected. Some other plants like myrtle and heather allow their upper parts to die but their stem remains alive. Stems act as storage organs, both above and below the ground. These produce buds and thus restore their species. Many plants hide themselves under the soil to escape from the cold, these include tubers, bulbs and roots which store their food according to their need. When summer comes they push out green leaves and new buds.

            Sometimes artificial methods are used to protect plants from frost, e.g. oil heaters called smudge pots are used in the region where citrus fruits are grown. In some places large fans are used to keep the cold air moving so that frost is not able to get deposited on the fruit trees.

How do different animals move?

There are millions of animals found on earth that moves about in hundreds of different ways. Some walk or run, while some others jump, crawl, swim, fly or glide.

The various types of movements of different land animals are as follows.

(a) Walking: Four legged animals walk by moving the fore-leg of one side together with the hind-leg of the other. This is the basic movement of animals with limbs. Insects which have six legs move fore and hind legs of one side with the middle leg of the other side so that the body is always supported firmly by the other three legs.

(b) Pacing or ambling: Elephants, giraffes, camels and a few other animals move both legs of the same side simultaneously.

(c) Trotting: This type of movement is characteristic of horses, cattle and many other four-legged animals. It requires a little effort and can continue for long distances.

(d) Galloping: In this type of movement all the four feet remain in air for some distance. This is very tiring. Horses and cheetahs can gallop at a high speed.

(e) Jumping: Kangaroos, frogs, grass hoppers, and fleas are excellent jumpers. They can jump to different heights.

(f) Contracting and expanding: Creatures like earthworm, slugs and snails move by passing a wave of contraction along their body. Among these animals waves of muscular contraction and expansion pass along the body from front to back.

(g) Crawling: A snake moves through muscle contraction and relaxation. It moves by wriggling along the ground or swinging its body in loops. It also crawls with the help of the overlapping scales on its belly with which it hitches itself on a rough surface effectively.

(h) Undulatory walking: This type of motion is peculiar to lizards. A lizard uses its legs for walking in the same way as a crawling baby. But because its belly rests on the ground, it undulate its body as well. Crocodiles, newts and salamanders also walk like this. 

Continue reading “How do different animals move?”

How do animals release their tension?

          Sometimes animals are caught in such a situation that they can neither run away from their enemies nor fight with them. In such situations they become very tense. Different animals react differently to get rid of their tense moments.

          To understand this mechanism of relieving tension let us take an example of a school boy who has done some wrong and is facing his teacher. He feels guilty and perhaps frightened also. He cannot run away or fight. He is caught in a tense situation, and somehow he must come out of it. So he does something looking incoherent like scratching his head or blowing his nose to fight off his tension. Such actions help him in relieving his tension.

          For instances, when a mouse is cornered by a cat and cannot escape, it will sit up and scratch its face with its forelegs. A bird which is frightened of a cat will make pecking movements (when birds start striking with their beaks). A monkey relieves its tension by uttering different sounds. Similarly, dogs relieve their tension by barking. All these actions are meant for getting rid of tension. These are called displacement actions. Animals act in such ways to regain their normal state. Sometimes they can cause harm to others. All these actions are their reflex actions. These actions help animals to survive.

          To demonstrate the reflex action a Russian scientist Ivan Pavlov carried out a famous experiment with some dogs. In this experiment, he showed some food to the dogs. Due to this their mouths got watered. At the same time he rang a bell. He repeated this for a few days and then began to ring the bell without showing the food. The dogs became so used to the association of the sound of the bell and the sight of the food that their mouths still watered even when food was not shown. This is called conditioned reflex action. This happens involuntarily when animals are trained for some purpose. They start doing these actions automatically. In a similar manner people learn studying and talking simultaneously.

How do living beings adapt to their environment?

               Adaptation is a biological term which means the process by which all living things change or adapt to new and unfavourable conditions for their survival. Thus human beings, plants and all other living things adapt to their environment for survival. 

               In plants, take the example of the oak tree. Since it grows in a moist climate, its green leaves require much water to carry on the process of photosynthesis. On the other hand, since the desert cactus cannot afford large leaves that would lose more water, its leaves are reduced to spines that grow out of a waterproof stem. To come to some animals, the beaks of birds are again adapted to particular ways of feeding. For example, preying birds like woodpeckers and kingfishers have sharp strong beaks to tear their prey.

               There are two kinds of adaptations: individual adaptation and group adaptation. In individual adaptation an individual adapts himself to new conditions automatically in his lifetime. Group adaptation refers to adaptation by a group. It is a slow process and occurs over many generations. For instance if a man’s job is such that he has to work during night time he would have to adapt to such a routine gradually. To begin with, he may have some difficulty in sleeping during the day but when adapted to the changing requirements after sometime, he would sleep easily. 

Continue reading “How do living beings adapt to their environment?”

Which animal can see with its eyes closed?

               There are about 2000 lizard species in the world including chameleon, iguana and skinks. Skinks are one of the two largest families of lizards. They are found in all the tropical countries but they are most abundant in Africa, East Indies and Australia. They belong to the Cincidae family. There are about 700 species of skinks. Skinks are shy and retiring, so people are mostly ignorant of them.

               Skinks have very thin, small legs. They have a smooth skin and a small pointed head. They can crawl over the uneven surface. Unlike snakes, thin jaw bones are fixed. Most of them are ground dwellers.

               A very strange characteristic of skinks is that they can see with their eyes closed. While burrowing or eating insects they close their eyes. They have a permanent, transparent eye lid cover over their eyes with which they close their eyes. As this lid is transparent, skinks can see with their eyes closed.

               Another characteristic feature of skinks is that they can squeeze their size during the squirming movement through the soil. In some skinks the feet look ridiculously small when compared to their body size and in others they get disappeared altogether.

               Some skinks lay eggs, others bear live young. These skinks include the tiny three-toed skinks of southern Europe and north Western Africa. They grow upto 40 cm long of which half is tail. Australian skink stores fat in its tail and looks the same from both ends. It feeds on fruits, insects as well as small animals.

               Now the question arises why skinks close their eyes? When skinks move in the dust, the dust can enter its eyes. So to protect against dust and sand it closes its eyes.

 

Which is the largest seabird?

               Albatross is the largest flying sea-bird. It can have a wingspan of 3.15 m (10 ft 4 in.) at full stretch. It belongs to Diomedeidae family and is found mainly in south of the equator. It has a long, heavy beak and long narrow wings which allow it to soar on the wind seemingly without effort for hours. Its body is about 1.2 metres long.

               There are more than a dozen species of Albatross. It experiences certain difficulty in taking off. It needs some wind and must run along the ground or paddle with its feet across the water for a long time before it can soar.

                Like other oceanic birds, albatross also drinks sea water. Although it normally lives on squid, it is attracted to ship’s garbage. It comes ashore only to breed in colonies on islands. It lays a single large white egg on ground in the open, which is incubated alternatively by the male and female parent. The growth of a young albatross is very slow. It attains flight plumage in 3 to 10 months, and then spends the next 5 to 10 years at sea, learning navigation and feeding techniques. Albatrosses live long and are among the few birds that die of old age.

               However, among the sea birds which use wings for swimming and not for flying, the largest is the Emperor Penguin of Antarctica. Standing over one metre high and weighing 40 kg, the Plum Emperor lives in the most remote shores of the great ice-bound continent.

               The largest ever recorded specimen of albatross was a very old male with a wingspan of 3.63 m. (11 ft. 11 inch). This was caught by the members of the Antarctic research ship in the Tasman Sea on 18 September, 1965.