Category Plants & Animals

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.

Where do crabs climb trees?

               It is established by the scientists that the most successful free living kinds of animals judged by the number of species and standing stocks of living substance, have come from marine surroundings.

               In 1964, Sir Vernon Wigglesword had suggested that, at first these animals might have lived along the shore lines and later moved in two directions. A part colonized the open sea and ocean deeps to give rise to crabs, crustacea etc and the other part moved to land areas.

               Crabs are mainly marine animals – although some live in fresh water or land. They are ten-legged alert carnivores that act as scavengers. There are many species of crabs worldwide; such as European crabs, shore crabs, edible crabs, fiddler crabs, river crabs, common hermit crabs and robber crabs.

               Among all these, robber crabs or commonly known as ‘coconut crabs’ are well adapted for living on land, although their larvae first live in the sea. But if an adult robber crab is left under water beyond 24 hours, it will be drowned ultimately. These are the crabs which can climb trees.

               The robber crab (Birgus Latro) is an extremely large land crab of South-West Pacific and Indian Ocean. Adults of robber crabs are about one metre long (40 inches) and weigh about 15-17 kilograms. A robber crab uses two large chelae or pincers to pound or chip coconuts to eat the soft white portion of the coconut. They climb coconut trees to detach coconuts from tree tops through they are quite unable to get inside a coconut on their own. They apparently eat coconut meat already broken into the ground by other means.

               The colour of a grown crab ranges from light violet to brown and deep purple with black strips on their legs. The female lays her eggs in sea. In larval state, it lives in water, feeding on small organisms. After about a month when it is grown to intermediate stage, it leaves water to live in a shell for 3-4 weeks. It then discards the shell and buries itself in moist sands, and transforms into an adult robber crab. Its meat is a local delicacy.