Do Whales and Dolphins sleep ?

When my son was in first standard , he  came to me asking this question , " Whales and dolphins are mammals. They breathe air through the nostrils located on top of their head ( called blowholes). Then can they sleep ? If they go underwater and sleep , how would they breathe ? Would n't they die if they forget to come to the surface of the water for breathing ?

I was little puzzled as I did not have the answer . I googled and explained the reason to him. Thanks to the technology advancement that parents have the right  answer at the click of the button ! Children have the ability to question  status quo which probably we adults lost over a period of time. The inspiration behind this blog is  my son. May be useful to all other parents and children too !

Answer is beautifully explained in "Howstuffworks".

­Whales and dolphins are mammals, so in a lot of ways, they are just like human beings.­ Among other things, they have similar bone structure, are warm-blooded and give birth to "live young." The biggest differences between these animals and human beings are related to our respective environments. Whales and dolphins have a unique respiratory system that lets them spend long periods of time (sometimes 30 minutes or longer) underwater, without taking in any oxygen. ­

­On land, human beings and other mammals breathe involuntarily: If we don't make a decision to breathe or not to breathe, our body will take in air automatically. Because of their undersea environment, whales and dolphins must be conscious breathers: They have to actively decide when to breathe. Consequently, in order to breathe, they have to be conscious. This presents a problem, since mammalian brains need to enter an unconscious state from time to time in order to function correctly (see How Sleep Works to find out why this might be).

­­There's plenty of time for a dolphin to catch a catnap between trips to the ocean surface, of course, but this isn't a viable option. When you're a conscious breather, it's just not feasible to be completely unconscious -- what if you don't wake up in time? The solution for whales and dolphins is to let one half of the brain sleep at a time. In this way, the animal is never completely unconscious, but it still gets the rest it needs.
Scientists have studied this phenomenon in dolphins, using electroencephalography. In this process, electrodes hooked up to the head measure electricity levels in the brain. The resulting electroencephalograms (EEGs) of dolphin brains demonstrate that in the sleep cycle, half of the dolphin's brain does indeed "shut down" while the other half is still active. Researchers have observed that dolphins are in this state for approximately eight hours a day.

We can't really know what this rest state feels like, but we can make a good guess. It is probably something like the semi-conscious state we experience as we begin to fall asleep. We're pretty close to unconsciousness, but are aware enough of our surroundings to wake up completely if we need to.

And where do dolphins and whales sleep? They could probably sleep anywhere, but it makes sense that they would do it near the surface of the ocean so they can come up for air easily. It's not uncommon to see dolphins "logging," swimming slowly along the surface, with very little movement. Presumably, these are dolphins at rest.

Interesting , is n't it ?

All About Plastics

                                                

A. HISTORY OF PLASTICS

Plastic comes from the Greek Word “plastikos” which means capable of being shaped or molded. This term was used even before plastic was invented, right from 1600’s.

First natural plastics are -

Tortoise shell                         Shellac (Insect Secretion)                         Tree Resins

                                           

Earlier days combs were made out of tortoise shells. Shellac is a resin secreted by female lac bug.  According to the Mahabharata, an entire palace was built out of dried shellac.

Plastic Invention – Time lines

Invention of Cellulose Nitrate -1840 - In the 1840s German chemist Christian Schönbein accidentally developed cellulose nitrate when he spilled mixture of  nitric acid, and sulfuric acid on his cotton apron . Cellulose is found in the cells of plants. Cellulose nitrate is a highly flammable dough like substance primarily used in the manufacture of explosives. Cellulose nitrate's properties as a molding substance interested other scientists of the time.

First man made (semi-synthetic) plastic -1862- British inventor Alexander Parkes  experimented with using a variety of solutions to dissolve cellulose nitrate, after which the material could be precipitated in one or another form. At first he called the reformulated cellulose nitrate "synthetic ivory," because of its similarity to natural ivory, but later referred to the product as parkesine, named after himself. This is the first man made plastic.

From this material, Parkes manufactured a number of buttons, pens and combs.

 

 

In 1862 he displayed this material officially at the Great International Exhibit in London. Parkes made small commercial gains with Parkesine and eventually sold the rights to Daniel Spill, who subsequently began production of the substance around 1865. But the cost of materials needed was very high.

Substitute for ivory made billiard balls- 1871- At around the same time in the United States, a billiard ball company advertised a $10,000 reward for the discovery of an alternate material to ivory. An American inventor, John Wesley Hyatt  and his brother developed a mixture of cellulose nitrate and camphor that was an even more satisfactory substitute for ivory than was Parke's parkesine. The Hyatts obtained a patent for their new product, to which they gave the name celluloid. In 1871 Hyatt and his brother Isaiah formed the American Celluloid Company, which is today the Plastics Division of the Celanese Corporation. However, the highly inflammable nature of celluloid was always a hazard to its manufacture and use, and as newer plastics materials became available its use gradually declined.

First Synthetic plastic- Bakelite- 1907 -Dr. Leo Baekeland engineered the first totally synthetic plastic in 1907. Compared to other plastics available at the time, such as celluloid, Baekeland’s thermosetting phenolic was more stable. Once molded, this new material would not burn or soften when reheated, or dissolve. Bakelite was an instant commercial success. It was electrically resistant, chemically stable, heat resistant, rigid, moisture and weather resistant. It was very widely used for its electrical insulating capability. Baekeland sold the rights to his invention to the Eastman Kodak Company that first used it for camera bodies. J.W. Hyatt, inventor of celluloid and founder of the Hyatt-Burroughs Billiard Ball Company, personally ordered his company to stop using celluloid and substitute Bakelite for their billiard balls due to its superior performance.

By the 1940s, many other polymers were introduced to the world, and these included acrylic, PVC, polyethylene, Teflon, nylon and others. In the following decade, plastic began to be used in numerous products, ranging from packaging to new textiles, and it also paved the way for the invention of innovative products such as televisions and computers.

B. TYPES OF PLASTICS AND THEIR USES

Plastics can be broadly classified into 3 types.

1. Elastomers ( Rubber like material)- The elastomers although elastic can not be reshaped by heating, hence they are heat resistant. They are usually used in the making of automobile tires.

Polyurethanes: Mattress, cushion, insulation, toys

Silicones:     Surgical gloves, oxygen masks in medical applications

2. Thermosetting plastics - Thermosetting plastics just like the elastomers once set after cooling cannot be reformed again and are extremely heat resistant. They are hard and durable.Thermosetting plastics when heated, will chemically decompose, so they can not be recycled. Yet, once a thermoset is cured it tends to be stronger than a thermoplastic Typically used in automobile parts and construction materials.

Unsaturated Polyesters: lacquers, varnishes, boat hulls, furniture

Epoxies and Resins:        Glues, coating of electrical circuits, fiberglass in helicopter blades, boats

3. Thermoplastics - Thermoplastics are recyclable and constitute 80% of the plastics used in the world. Thermoplastipolymers melt when heated and return to their original state when cooled again. Thermoplastics can be remelted and remolded. For example, a plastic bottle that contained a soft drink could be reformed into the fibres of a fleece jacket.

C. How plastics are made now ?

Though earlier plastics were made from plant parts like cellulose , now a days most synthetic plastics come from crude oil but coal and natural gas is also used.
When crude oil is refined gasses are given off. The gasses are broken down into Monomers. These are chemical substances consisting of a single molecule. Thousands of these are linked together in a process called Polymerization to form new compounds called Polymers. By the application of heat and pressure to the plastic granules, we can get the required shape. Several processes like injection molding, extrusion, compression molding, transfer molding etc. are used to make the plastic products.

D. Plastic – Is it a boon or bane?

Plastic is a boon

because plastics are everywhere! From our pillows and mattresses (cellular polyurethane or polyester) to cars and hi-tech computers, plastics are there.

1. Plastic has replaced metals and glass as the primary material used.

2. Plastics are poor conductors of heat and electricity. Hence they provide good insulation for the wiring and are durable in extreme weather conditions.

3. Since plastic is able to withstand heat, they are widely used in space shuttles.

4. They are light weight and colorful.
5. Safe for children when they are food grade plastics. Ordinary plastics cause health hazards to humans when eaten in them.
6. Handy as disposable bags, carry bags, wrapping paper, etc.

7. They are non-reactive and hence used as water pipes. Plastic bottles can be used to store juices.

8. In fact, plastic has helped in advancements in satellites, shuttles, aircraft, and missiles. As a result, civilian air travel has improved, as well as military air power and space exploration.

Bane because

1.   Non biodegradable. Plastics pollute beaches and oceans. Plastic bags litter the landscape.

2.  Plastic bags litter the landscape.

3. Obstruct underground water percolation.
4. Microbes cannot destroy them.
5. Produce harmful gases when burnt.
6. Plastic bags thrown into the open drains and sewers clog them and cause stagnation of water, which in turn poses health hazards
7. Disposable syringes, drip bottles, blood and urine bags and other medical accessories when disposed off in an irresponsible manner, cause a lot of serious health problems.
8. Animals sometimes feed on plastics and die painfully as plastic chokes their digestive and respiratory tracts.

E. Measures to reduce plastic pollution

Since it is obvious that plastic cannot be routed out completely,we must at least try and reduce our dependency on it.

3 ways to minimize the bad effects of plastic on envirionment  is  the ’3R’ policy –

 Reduce, Reuse and Recycle.

Reduce

1. Avoid accepting plastic bags when you finish shopping. Instead, carry a paper or a jute bag with you when you go shopping.

2. Avoid using plastic chairs or tables, you could use wood/metal instead.

3.  Plastic is made from crude oil. So less usage of plastic also means less demand for crude oil products.

Reuse

1.    More than 90 percent of consumers reuse their plastic grocery bags at home for purposes ranging from waste basket liners to lunch bags to pet clean up

Recycle

1.   Do not dispose plastic which can be recycled. That’s another means to reduce production of more plastic. The plastic that undergoes the recycling process results in a lower quality product. Hence, such plastic has reduced application range in today’s world. Our aim should be to increase the domain of usage of such lower quality plastic and ensure that we have an equal demand for recycled plastic as much as we have for good quality plastic

The more hazardous variant of plastic, the non-recyclable poses a greater threat to our environment.

A few steps that could be taken to tackle this problem are

1.    Governments should ban production of non-recyclable plastic and also the manufacture of products that use them.

2.    Non-recyclable plastic can be used for asphalting roads, as supplementary building materials, and as supportive structures.

3.   Extensive research must take place in finding better methods of disposing non-recyclable plastic.

4.   People must be educated about the benefits of recycling and must be taught to avoid the usage of non-recyclable plastic.

5.   Avoid disposing of plastic along with organic wastes. Do not throw waste foodin plastic bags or containers. You might just save a life.

6.    As common people, the least we could do before buying a plastic article is tolook at the label to find out if it is recyclable.

7.    Avoid disposing of plastic along with organic wastes. Do not throw waste food in plastic bags or containers. You might just save a life.

 

Does cutting down trees affect rains ?

My son asked me the other day, "Does cutting down trees affect rains?  

Yes. It does. Trees are necessary for rain. Trees creates cold and humid atmosphere required for rain. 

Water from ponds, lakes, rivers, seas get evaporated due to the heat of the sun and rise as water vapor.   As we go up in the atmosphere, it is cooler. So, at maximum height in the atmosphere, the water vapour in the air condenses and tiny water droplets are formed. These tiny water droplets floating in the air along with dust particles are called clouds. As the clouds move up further, it is even cooler. Water droplets come together to form larger water droplets. The larger water droplets are so heavy that air cannot hold them. There fore they fall down as rain. If the temperature is very low, the water droplets freeze in the atmosphere and fall as hail or snow. The coming down of water in the form of rain or hail or snow is called precipitation.

Important thing to note is that the water vapour is also added by the plants through a process called transpiration. Let is look at what is transpiration. 

1. Transpiration is the process by which plants return water to the atmosphere. After absorbing water from the ground, plants release water through their leaves. Transpiration helps plants stay cool, in the same way perspiration keeps humans and animals cool.

2. Plants and trees have pores on their leaves – stomata – which enable the exchange of gases such as carbon dioxide between the leaves and the surrounding air.  When stomata open, water droplets are released and usually evaporate from the leaf’s surface. This process is known as transpiration and provides an important source of moisture for cloud formation and rain. 

How much water do plants transpire?

An acre of corn gives off about 3,000-4,000 gallons (11,400-15,100 liters) of water each day, and a large oak tree can transpire 40,000 gallons (151,000 liters) per year.Large rainforests (and their humidity) contribute to the formation of rain clouds, and generate as much as 75 percent of their own rain.

This continuous movement of water from the earth's surface, water bodies and plants as water vapour to the atmosphere and back to earth's surface as rain hail or snow is called water cycle. This cycle maintain the supply of water on land.

So, trees play a very important role in maintaining the supply of water.  Let us conserve trees.