My Science School

The truth is that the glow is only the reflection of light from some other source. The reason that reflection takes place is that there is a layer of crystalline substance in the eyes of many animals. This substance has the ability to reflect light. This reflecting layer also helps the animal to see in the dark, which is why they can see better at night than man can.

The difference in the colour of the light reflected from the eyes of the animals is due to the different number of blood vessels in their eyes. An animal that has many blood vessels in its eyes will reflect a reddish glow. If it has fewer numbers of blood vessels, it will have a whiter glow.

            Bees live in colonies called hives. Each colony has one queen bee, few drones (males) and thousands of workers (females). The queen manipulates the behavior of the workers through various pheromones. A successful forager bee communicates information about the source of food discovered by them to the others upon returning home. This they do by means of a round dance or a waggle dance.

            During a round dance, the forager runs in small circles clockwise and anticlockwise, alternately. In the case of waggle dance the bee dances tracing a figure of eight. The round dance is performed if the food is far away. The waggle dance is said to convey information on the distance between the colony and the food, the direction in which the food is located and the quantity available. The dancer also carries the smell of the pollen and/or nector that it recently came across.

            Thus by this peculiar dance the bees find their way to the sources of food and the way back to the hive. This dance was first found by an Austrian zoologist Karl Von Frisch which got him the Nobel Prize in 1973.

            Besides the dance, the bees are also said to have various other ways of remembering their way home. They are said to possess excellent mathematical instinct. They return to their hives by remembering the angles of the triangle formed by the position of the hive, the sun and the bee though this may vary with time. As a result, they cannot spend more than half an hour at their target. When there is no wind they fly high but remember the angles. When the sky is cloudily or when there is a strong wind they fly at low levels remembering a few permanent marks on fields. They can identify almost all different geometrical forms and colours, scent and sound.          

            According to Frisch, the bees can perceive polarization of sunlight and thus use the sun as a compass. Even on overcast days they do not lose their sense of perception. Its sense of smell is also close to that of humans and they can distinguish all colours except red, it is said.

            As the heart is on the left side, for humans and animals, running anticlockwise makes the centrifugal force in the body to act from left to right. Whereas it is from right to left for clockwise running.

            Superior venecava (the principal vein carrying blood to the heart) takes blood to the heart aided by heart suction. This vein carries blood from left to right.

            Centrifugal force due to anticlockwise running helps this suction. If we run clockwise, the centrifugal force impedes suction. That is why, in olden days, health officers ensured that all carnival merri-go-rounds were run only in the anti-clockwise direction.

            Racing tracks, animal shows in circuses, bullock-drawn pelton wheels, all mostly have only left turns. Stairways in temple towers have only left turns for going up. Clockwise running tires people, especially, children, easily.

      In humans hair is present in the skin of nearly every part of the body excepting the palms of hands, the soles of the feet, and the flexor surface of the digits. The structural components of the skin alone decide the generation of the appendages of the skin. Structurally the skin has two layers: the Epidermis and Dermis. Among these two layers, the epidermis has a high capacity for regeneration after damage. It continually replaces the outer dead cells and also generates the appendages of the skin, like hairs, nails, sweat and sebaceous glands.

            In the two parts of the hair, namely the root and shaft, the root is the structure which emerges first during development and is called the hair follicle. It is set in between of the epidermis and the superficial part of the dermis. Each hair follicle commences on the surface of the skin with a funnel shaped opening. From this opening the follicle passes inwards in an oblique or curved direction.

            At the deep end of each here follicle there is a small conical vascular eminence called papilla, which is continuous with the dermal layer of the skin. The capillaries of the papilla provide nutrients to the hair.

            When any one of the layers of epidermis and dermis gets abnormal development it affects the formation of the hair follicle and also becomes an unfit layer to support the hair.

            For example, in the skin of palm and soles the stratum cornium of the keratinization zone of epidermis and reticular layer of dermis are comparative thicker than in the skin of other parts of our body.

            Such a thick keratinization zone will not allow the formation of hair follicles and the thick dermis is not the ideal structure to support the germinal matrix of the hair follicles. That is why hairs do not grow on our palm of the hands and the soles of the feet.

  The difference between mammalian hair and fur is chiefly one of arrangement, not structure. Hair tends to come individual strands that are fairly coarse, as well as being patchy in concentration.

            In people, for example, there is little in the genital area and underarms and some on the male face and chest, plus a dusting of individual, visible separated hairs on the rest of the body.

            Fur on the other hand, tends to coat the body of the animal in a closely packed arrangement, so that the naked eye finds it difficult to distinguish the individual hair roots. Fur is also usually finer in texture than hair.

            Typically, fur has two or more layers: a short, dense, soft undercoat of barbed hairs and longer guard hairs. Fur’s function is to trap pockets of dead air, providing warm insulation for the wearer.

         

 

 

 

 

  Generally animals and plants are attracted towards light. This tendency is termed phototropism or photo taxis. Animals which towards the source of light are known as positively phototropic and others that shun light are called negatively phototropic. Most of the insects are positively phototropic but the degree of attraction differs. And some are negatively phototropic. Bed bug shows negative phototropism. Mosquitoes shun intense light, but in dim light they display positive phototropism. This behaviour differs in different species of insects with the exhibition of the following traits.

            Insects without eyes also exhibit phototropism. The photosensitivity is distributed or diffused throughout the dorsal surface of insects so photo stimulation can occur even if the insect does not possess any eyes. Some insects are more sensitive to light rays. Their surface cells and eyes are more refined to perceive and follow light sources.

            Some are attracted towards yellow light and some towards mercury light etc. well illuminated areas are used as mating grounds by male insects, full of matured sperms and females with matured eggs.

Adult females (about 6 mm long) of the mango nut weevil Sternochetus mangiferae Fabr puncture the tender fruits just under the rind and lay about 12-30 eggs singly. These punctures leave black or brown marks on the skin.

            A gum-like secretion oozes out of the punctures and cover the eggs. These punctures heal in due course as a result of which the ripe fruits appear unaffected. However, the black marks can be seen sometimes even on ripe fruits.

            Legless fleshy larvae emerge out of the eggs after a week. They tunnel through the developing un-ripened pulp and enter the tender nut which is soft. The nut hardens later as the fruit matures. The larvae thrive on the cotyledons of the nut. They pupate there after three weeks and dark brown adults emerge. Their life cycle lasts for 35-50 days.

            The adult weevil rarely comes out of the ripened fruit. Their attack increases the number of fallen fruits. They hibernate in the crevices and bark till the next fruiting season. The weevil uses the oxygen present in the fruit for respiration.

            The beetle generally attacks soft-pulped varieties such as neelam, mulgoa, banglora, Romani, jehangir, surangudi and padhiri.

            

            Eagles adopt an energy-saving flight mode called gliding. Their broad wings and broad rounded tail enable them to exploit thermals in the air. (Thermals are upward air currents in the atmosphere caused by the absorption of heat, from the sun or land, by the air.)

            The birds flap their wings slowly and laboriously in the air in wide circles, but once they catch the rising air they begin to soar effortlessly without even a single beat up to a point where the warm air has cooled and stopped rising.

            From this point, they start gliding down to another thermal, which they spot by seeing other groups of rising raptors or perhaps by their delicate sensitivity to even minute changes in air currents. Their primary feathers are spread out to obtain the maximum advantage from the rising air. The wing tips are broadly splayed or ‘fingered’ to reduce turbulence in the air surrounding it. They also assist in gaining speed when the bird glides downwards.

            Sea birds such as albatrosses, fulmars, gannets and Manx shearwater also adopt gliding but a slightly altered version. As thermals do not form over the sea, they take a shallow downward glide across the wind then turn into the wind and climb steeply until they resume gliding in their original directions. They thus use relative wind speeds to power both the climb and control the long, downward glide over the sea. These birds can cover thousands of kilometers without expending much energy.

To keep our torsos stable and conserve energy, we swing our arms backwards and forwards while walking. When you swing, say, your right leg forward to take a step, you provide a rotational moment about the central vertical axis of your torso. By the principle of conservation of angular momentum, an opposite reactionary moment is felt by your torso. By swinging your right arm backwards and your left arm forwards, you counterbalance this moment. Just try running without swinging your arms at all. Or worse still, try running while swinging your arms in the opposite directions to normal: that is, swing your left arm forward when you swing your left leg forward and so on. You will find that your torso rotates from side to side in an uncomfortable and unnatural manner.

            Of course, legs are heavier than arms, so as to ensure that the moments are the same; evolution has ensured that our arms are further from the central axis of our bodies than our legs are. This allows the moments from our legs and our arms to be roughly equal.

            Going back a few steps (pun intended), Serge Gracovetsky hypothesized in the 1980’s that the spine, rather than the legs, is the primary source of power for gait, and this is now accepted by most, if not all, researchers in this fields.

            Many bilateral amputees, for example, can walk successfully. The mechanism works because the spine is curved. Any attempt to straighten such a structure will result in a twisting action.

            The lumbar muscles acting on the lumbar spine cause such a twist and provide the main impetus for placing one foot in front of the other.

.swinging one’s arms while walking assists in this twisting motion, increase efficiency, and reduces the physiological cost of walking. Indeed, nearly everything that we do naturally when moving is done purely to reduce the amount of energy that is expended in order to achieve the desired result.

            Other two-legged walking animals balance themselves by synchronizing the movement of the backbone to the side of the leg that stays in contact with the ground.

            This keeps their gravitational centre close to the standing leg. It is seen in chickens and, to better effect, in penguins.

     Hairs are the appendages of the skin generated from the epidermal layer. Hair is a made up of Keratin a highly insoluble and mechanically stable fibrous protein. This Keratin is not only found in hairs but also in the skin. Actually Keratin is produced from the Keratinisation zone of the epidermis, which is the outer most layer of the skin. In the skin it provides water proofing quality.

            The Keratin is generally pigmented. It is intensively pigmented in the hair. The dark black colour of the hair is due to the presence of high concentration of melanin pigments in it. The skin colour is also due to the presence of this pigment in the keratinocytes.

            The Keratin gets its melanin pigments from melanocytes, which are found in the inner layer of the epidermis, which is found just beneath the keratinizing layer. The melanocytes have long progresses which extent between and under the cells of the epidermis. The melanin granules formed in the melanocytes pass along their branches and are secreted at their tips. The granules are subsequently engulfed by the keratinocytes, which make up 90 per cent of the epidermal cells.

            Melanin is a protein like polymer of the amino acid tyrocin. In its biosynthesis tyrocin is converted in to dihydroxy phenyl alanine (DHPA) by oxidative enzymes amongst which tyrocin is particularly important. Then a series of reactions take place during which polymerization occurs to form the final melanoprotein.

            The hair grows only from the keratinocytes of the germinal matrix of the hair follicle. This germinal matrix lies in the proximal enlargement of the rot hair, called the hair bulb. The shaft, which projects from the surface, consists of an inner medulla, an intermediate cortex and an outer cuticle. All these parts are made up of cornified cells.

            The medulla is composed of polyhedral cells; the cortex consists of elongated cells with inner lumen. These cells are united to form flattened fusiform fibers. The lumens of these cells contain pigmented granules in dark hair and air space in white hair.

            The development of white hairs because of the absence of melanin pigments, may be due to the absence of one or more enzymes, necessary for the DHPA path way. It will lead to the failure of melanin accumulation in the keratinocytes, found in the hair bulb, from which hair is growing.

            Usually such physiological disorder occurs in the old age, which results in the growing of gray and white hairs in the body.

         

 

 

 

 

 

 

  There are many theories explaining this capability of birds. According to one of them, the Sun’s rays and the direction of winds help them to navigate. Birds’ extra sensory capabilities assist them in this task and direction them with the help of the Earth’s magnetic field.

            Another theory suggests that these winged wonders understand star-maps so well that it helps them to rack their way. But no one answer has been put down for this as of now.

            Birds have the capability to detect changes in atmospheric pressure, weather and earth’s magnetic field. Based on these they locate specific regions and find their home. But the most important navigational aid is said to be “internal magnetic compass” that they are said to posses in their brain. The compass works in relation to the earth’s magnetic field. The magnetic currents generated here are turned into flight paths.

            As a result, disturbances in Earth’s field can seriously affect bird’s judgment. In July, 1998, 3000 homing pigeons that set off for their return journey from northern France to southern England could not reach their destination because an explosion on the surface of the Sun, a few days prior to their journey, had sent radiations that disrupted the Earth’s magnetic field. As a result their internal magnetic compass picked up confusing signals and the birds lost their way.

            Yes, sheep do swim, said Edward Spevak, assistant curator of mammals at the Bronx Zoo. “It’s basically instinctive, a life-saving device,” he said. They don’t go swimming every day, but in case of flooding, or falling into a river, in essence they know how to swim. Sheep have never been known as big swimmers, and mose of the habitat where they evolved does not have a lot of water resources, but swimming is part of their repertoire of skills, he said.  First of all, like many animals, they float, Spevak explained, “Then, in struggling to keep the head above water and to keep breathing, the method they use is basically fast walking, which constitutes a kind of dog paddle,” he said.

            Other large mammals are swimmers, too. Spevak said. Cattle can swim when herded across a river, as Western movie fans know. Deer can swim, as well, “The moose, the largest deer in the world, actually feeds in water and is a very good swimmer.” Spevak said.

    It is generally believed that anything red makes a bull angry and causes it to attack. Therefore, the bull fighter has to have a bright red cape and use a red cloth.

            The truth is that if the bull fighter had any other coloured cloth he would be able to accomplish the same reaction from the bull. Bulls are colouring blind.

            Many experiments were conducted where they used white cloth and got the bulls to behave in the same way as with the red cloth.

            The reason is the movement of the cap and not colour of the cloth brings about the reaction in the bull. Anything waved in front of a bull would excite it.

It is a partly a matter of appearances, with zoo animals less active at peak visiting hours, and partly a matter of normal rhythms of carnivore life. It is said that lions in the wild are normally inactive for 20-22 hours a day because they need to conserve their energy for hunting. They can never be sure where their next meal will come from.

As for the house cat, although it does know when the next can will be opened, the basic behavioural pattern is the same. Even a cat that has never seen real prey will stalk a butterfly through the window.

Young animals can afford to do that, but from an evolutionary point of view, old lions especially must conserve their energy for the business of surviving. At some point of life, their metabolism does begin to slow down, and a sedentary cat may become overweight.

In general, many zoo animals are from hot climates and are most active in early morning and late afternoon. They sensibly lie low from 11-3 on a hot day, so visitors should try to come early in the morning. Zoo animals have the benefit of a nutritional staff that prepares diets as close to natural as possible. Modern zookeepers also make sure that animals mimic natural behaviour, living in groups, with plenty of space, and foraging and competing for food. Some do get chunky, like the dominant animal in a group that always gets its fill, but most stay lean.

 

 

 

 

 

 

 

            Cats have a superb vestibular system and make gyroscopic turns, while falling, so that all the four feet quickly point downwards, regardless of their orientation at the start of the fall. This enables them to dissipate the impact force, of the fall, through all the four limbs and have a higher survival rate compared to other animals like dogs. This lends credence to the old adage that cats have nine lives. Cat-specific advantages are believed to have evolved through natural selection, according to Prof. D. Balasubramaniam, Director Centre for Cellular and Molecule Biology, Hyderabad.

            A cat falling from great heights (say100 ft) extends its limbs, reflexly, more horizontally in a flying-squirrel fashion. This reduces the velocity of the fall besides absorbing the impact over a greater area of its body, say scientists. Also, when falling, the animal does so with its limbs flexed so that much of the impact is dissipated through its soft tissues. This is the same reason why parachutists are trained to dissipate impact forces by lending with knees and hips flexed, than rolling, (J.M. Diamond, Nature, April 14, 1988).