Category Physics

 Birds have nifty tendon arrangement in their legs. The flexor tendon from the muscle in the thigh reaches down the leg, round the ankle and then under the toes. This arrangement means that, at rest, the bird’s body weight causes the bird to bend its knee and pull the tendon tight, so closing the claws. Apparently this mechanism is so effective that dead birds have been found grasping their perches long after they have died.

            Yes, birds do sleep. Not only that, some do it standing on one leg. And even more surprising, may be hypnotized into sleep at will. To try it, we will have to bring our eyes close to the cage, and use the hypnotist’s principles on our eyes. If we act as if we are gradually falling asleep the bird will follow us, finally holding one leg up under its belly, tucking its head under its wing and falling into a deep sleep.

            What’s more most pet bird owners know that all we need to do make the pet fall asleep is to cover the cage with a blanket to simulate night.

            Birds do sleep, usually in a series of short ‘power naps’. Swift are famous for sleeping on the wing. Since most birds rely on vision, bedtime is usually at night, apart from nocturnal species, of course. The sleeping habits of waders, however, are ruled by the tides rather than the Sun. some other species are easily fooled by artificial light. Brightly lit city areas can give songbirds insomnia.

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.

  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.