How do crickets chirp?

Crickets, any of various grasshopper-like insects of the large order Othoptera, are noted for singing. They have on their hind legs, special noise-generating equipment and ears to receive the sounds. Stridulation, normally by males, plays an important role in the courtship of many species. The song differs between species, thus ensuring that only females of the correct species are attracted for mating. The song may also be important for males in distracting from one another. There are 2 basic mechanism used by these insects to sing. In one, specialized veins on the bases of the forewings are rubbed together. This is a tooth and comb technique. It is found mainly in species of the sub-order Ensifera (crickets).

The other mechanism used largely by the sub order Caelifera (locusts and short-horned grasshoppers) could be termed as wash board technique as it involves friction between a ridge or rows of pegs on the inside of the hindleg and one or more pronounced veins on the forewing. Many other techniques are employed but these are the most characteristic of the order. Ears of the orthopterans are found on the abdomens or legs and consist of a thin membrane to the back of which are attached specialized receptors. Due to the design of the sound producing apparatus orthopterans produce loud sounds. However one family, the mole crickets burrow in such that it magnifies his song so that on a still evening it may be heard 2 km away. Recent and sophisticated advances in the loud speaker design have recently produced, with the use of a computer, something which appears to copy almost exactly the burrow of a mole cricket.

The life cycle of an insect inside a mango fruit?

The insect pest inside the mangoes is the mango nut weevil or stone weevil,’Sternochetus Mangiferae’ the young one or grubs as soon as they hatch out from the eggs tunnel in a zig zag manner through the pulp, endocarp and seed coat and finally reach the cotyledons.

As the fruit develops, the tunnel gets closed. The grub feeds on the cotyledon and destroys them. The adult emerges from the pupae also and feeds on the developing seed and this may hasten the maturity of the infested fruits. The adults hibernate in between the crevices on the tree trunks. The weevil attacks only mangoes.

The dark brownish stout weevil measures about 6mm long. The female scoops out the surface of the developing fruit and deposits the eggs singly. On fruit 12 to 46 eggs may be deposited. The fluid that oozes from the fruit covers the eggs. The incubation period is 7 days.
The grub is apodous, fleshy, light yellow

How does pearls form?

Pearls are formed from pearl oysters. They are part of a group of animals belonging to the group ‘bivalva’. This includes snails, slugs etc. pearls are grown in live oysters far below the surface of the sea. These oysters have a hard shell covering their body. In between the shell and its body there is an empty space called mantle.

A natural pearl begins its life as a foreign object, such as a parasite or piece of shell that accidentally lodges itself inside the mantle from where it cannot be expelled. It causes some irritation to the oyster. To ease this irritant, the oyster’s body begins to secrete a smooth, hard crystalline substance around the irritant. This substance is called ‘nacre’. As long as the irritant remains within its body, the oyster will continue to secrete nacre around it, layer upon layer.

Overtime, the irritant will be completely encased by the silky crystalline coatings. And the result is a lustrous pearl. Nacre is composed of microscopic crystals of calcium carbonate, aligned perfectly with one another, so that light passing along an axis of one crystal is reflected and refracted by another to produce a rainbow of light and colour.

Pearls can be cultured from oysters artificially in an almost identical fashion. The only difference is that a person carefully implants the irritant in the oyster that posses superior pearl-producing qualities. In a process called nucleation or grafting or seeding, skilled technicians carefully open live pearl oysters that posses superior precision make an incision in its body. They place a tiny piece of ‘mantle tissue’ from another oyster into a relatively safe location. Then, they place a small round piece of shell, or ‘nucleus’, beside the inserted mantle tissue.

The nucleus is a mother-of-pearl bead made from freshwater mussel. The cells from the mantle tissue develop around the nucleus forming a sac, which closes and starts to secrete nacre, the crystalline substance that forms the pearl. The nucleated oysters are then returned to the sea where, in sheltered bays rich in nutrients, they feed and grow, depositing layer after layer of lustrous nacre around the nuclei implanted within them.

The oysters are given the most utmost care during this time, while suspended in the water, from the rafts above. Technicians check water temperatures and feeding conditions daily at various depths, the oysters up or down as appropriate. Periodically, the oysters are lifted the sea for cleaning and health treatments. Seaweed, barnacles and other sea borne organisms that might interfere with their feeding are removed from the oyster’s shells. The shells are also treated with medicinal compounds to discourage parasites. After months of rest oysters are ready for harvest. Those that have survived are bought ashore and pearls are harvested. Saltwater cultured pearls can never be mass-produced. Millions of pearls are nucleated every year, but only a small portion live to produce fine quality pearls. Many oysters don’t survive nucleation; others are weak and fall prey to disease.

What is a bionic eye?

Bionic eye also called a Bio Electronic eye is the electronic device that replaces functionality of a part or whole of the eye. It is still at a very early stage of development, but if successful, it could restore vision to people who have lost sight during their lifetime. The principle of Bionic eye is very similar to that of a bionic ear. Bionic eyes and Bionic ears both work by stimulating nerves, which are activated by electrical impulses.



In both cases the patient has a small device implanted to the body that can receive radio signals and transmit those signals to nerves. The healthy human eye has millions of biological solar cells in the retina, called the rods and cones that convert light into electrical signals, which are sent along the optic nerve to the brain where images are formed.

In cases where the retina fails, the nerves behind the retina, which carry electrical impulses, still function. Many people are blind because of the malfunctioning rods and cones. Retinitis pigmentosa and macular degeneration tends to be hereditary and may strike at an early age, while macular degeneration mostly affects elderly.

Currently researchers around the world are exploring ways of restoring sight to the people with retinal degeneration in two methods. One method uses a small video camera-equipped device to capture images, encode them and sent them into eye implant (a silicon chip inserted into the eyeball) via a laser beam that also powers the chip’s solar cell.

Photo sensors convert the light and images into electrical impulses, which charge a plate that stimulates the nerves and transmit the visual information to the brain. The laser and camera can be easily be mounted on eyeglasses without having to wear bulky headgear.

In another method, microchips replace the eye’s malfunctioning natural sensor with an artificial sensor (silicon retina), manufactured on a piece of silicon. When the chip is implanted into the back of the eye and strikes those solar cells, the light is converted into electric signals that travel via the optic nerve to the brain and are interpreted as an image.


Development continues to gauge the compatibility of silicon with living tissue as silicon is toxic to the human body and reacts unfavorably with fluids in the eye, and to make the microchip as non-invasive to the eye as possible. Preliminary tests are on going on the ceramic detectors for biocompatibility, and they appear to be totally stable.

How do mosquitoes locate the source of blood in both humans and animals?

When adult mosquito emerge from the aquatic stage they mate, and the female seeks a mammalian blood meal to obtain protein necessary for the development of her eggs. Mosquitoes are attracted by perspiration, warmth, body odour, carbon dioxide and light. Scientists are still investigating the complexities involved with mosquito-host acceptance and rejection. Some people are highly attractive to mosquito while others are not.

Mosquitoes have specific requirements to satisfy and process many different factors before they feed. Many of the mosquito’s physiological demands are poorly understood and many of the process they use to evaluate potential blood meal hosts remain a mystery. Female mosquitoes use the CO2 we exhale as their primary cue location.

A host seeking mosquito is guided to our skin by following the slip stream of CO2 that exudes from our breath. Once they have landed, they rely on a number of short range attractants to determine if we are an acceptable blood meal host.

Folic acid is one chemical that appears to be particularly important, fragrances from hair sprays, perfumes, deodorants and soap can cover these chemical uses. They can also function to either enhance or repel the host seeking drive. Dark colour captures heat and makes people more attractive. Detergents, fabric softeners, perfumes and body odour can counteract the effects of flour.

How do snakes shed their skin every month?

Skin of snake consists of outer epidermis and inner dermis. The inner dermis (soft, fibrous and pliable) contains pigment cells that give characteristic colour patterns. The outer epidermis Keratinised layer (stratum corneum) made up of horny scales, resists normal wear and tear and protects from injury.

The Keratinised layer is shed sloughed every 60-70 days or earlier or 3-4 times a year. In young ones and some species the rate of casting may be higher or once in a year. The snake, normally hiding just before casting, is lethargic. New epidermis is grown beneath the old skin and secretes a thin layer of fluid between old and new skin.

Shedding parts by opening and secreting the mouth and rubbing it on the surrounding available objects until the old skin under at the edges of the lips begins to split. The process of rubbing continues till the skin is shed in one piece from head to tail or sometimes the skin will break up and come off in pieces.

The skin, turned out like a tight glove being pulled off from hand, is a perfect cast of the snake including eye scales. This process takes nearly half an hour or more. The cast is completely devoid of colour as the pigment cell remain in the dermis is never shed. The shedded skin is transparent and brittle. After casting the snakes become fresh, alert, active and bright. The sloughing indicates growth of snakes and it is affected by factors such as health, environmental temperature and amount of food taken.

Why do humans want to brush their teeths while animals don't want?

Teeths are hard white substances found n the mouth of humans and in many other animals and s used for mastication.Some characteristics like morphology of teeth and food habits warrants brushing of teeth in humans but it is not so in case of animals.

First we will see the adaptation in the teeth of animals, which does not necessary brushing in them. For e.g. the teeth of snake are very thin and sharp and usually curve backward. They function in capturing the prey and not in chewing, for snakes swallow their food whole. The teeth of carnivorous mammals like cats and dogs are more pointed and adapted to cutting and shearing.

The difference in shape of teeth is functional adaptations. The plant cells used as food by herbivores in cellulose cell walls. This necessitates its chewing of food in order to break down he cell walls. Although the teeth come to play, nature of the food is raw, fibrous and no sticky. So brushing is not necessary because it does not cause any probs to the dentition.

By contrast, animal cells in meat are not encased in cell walls and can act upon directly by digestive enzymes. This is the case in carnivores, where chewing is not necessary. Their teeth come to play only when cutting and shearing the prey. This reason for non brushing of teeth in animals. Humans who are omnivores have teeth somewhere between the extremes of specialisation attained by the teeth of carnivores and herbivores.

Tooth brushing in humans is mandatory because of the following reasons: modern refined diet that has ready fermentable carbohydrates which is prone to cause caries, to prevent dental caries and periodontal diseases, to aid in plaque control, to maintain good oral hygiene. Therefore the morphology of teeth in humans necessitates brushing because of soft and sticky diet consumed by modern man. It is also indicated in order to prevent the dental diseases and to maintain hygienic status.