Archive for October, 2009

Sunday article – Vanishing Species: Sharks

Sunday Article by Mohan Pai

 
 
Shark
(Selachinmorpha)

The great predator.
 
 
Virtually unchanged for more than 400 million years, shark’s streamlined bodies and amazing sensory systems fit the mold of a perfect predator.
 
Sharks are a type of fish with a full cartilaginous skeleton and a highly streamlined body. The earliest known sharks date from more than 420 million years ago, before the time of the dinosaurs. Sharks are found in all seas and are common down to depths of 2,000 metres (6,600 ft), and some live even deeper but they are almost entirely absent below 3,000 metres (9,800 ft). They generally do not live in freshwater, with a few exceptions such as the bull shark and the river shark which can live both in seawater and freshwater. They respire with the use of five to seven gill slits. Sharks have a covering of dermal denticles that protect their skin from damage and parasites and improve fluid dynamics so the shark can move faster. They have several sets of replaceable teeth. Well-known species such as the great white and the hammerhead are apex predators at the top of the underwater food chain. Their extraordinary skills as predators fascinate and frighten us, even as their survival is under serious threat from fishing and other human activities.
 
 Extraordinary Sensory System
Sharks have sensory organs unlike any other creatures. Most sharks can:
* Pick up sound waves from more than 5 kilometers.
*Detect a single drop pf blood in an amount of water contained in an Olympic size swimming pool.
*Register the heightened body tension of a wounded or panic-stricken creature.
* locate prey in total darkness.
 
Unlike bony fish, sharks have no bones; their skeleton is made of cartilage, which is a tough, fibrous substance, not nearly as hard as bone. Sharks also have no swim bladder (unlike bony fish).
 
 Size & Shape
 
There are many different species of sharks that range in size from the size of a person’s hand to bigger than a bus. Fully-grown sharks range in size from 7 inches (18 cm) long (the Spined Pygmy shark), up to 50 feet (15 m) long (the Whale shark). Most sharks are intermediate in size, and are about the same size as people, 5-7 feet (1.5-2.1 m) long. Half of the 368 shark species are under 39 inches (1 m) long.
 
 Sharks have a variety of body shapes. Most sharks have streamlined, torpedo-shaped bodies that glide easily through the water. Some bottom-dwelling sharks (e.g. the angelshark) have flattened bodies that allow them to hide in the sand of the ocean bed. Some sharks have an elongated body shape (e.g., cookiecutter sharks and wobbegongs). Sawsharks have elongated snouts, thresher sharks have a tremendously elongated upper tail fin which they use to stun prey, and hammerheads have extraordinarily wide heads. The goblin shark has a large, pointed protuberance on its head; its purpose is unknown.
 
 There are about 368 different species of sharks, which are divided into 30 families. These different families of sharks are very different in the way they look, live, and eat. They have different shapes, sizes, color, fins, teeth, habitat, diet, personality, method of reproduction, and other attributes. Some types of shark are very rare (like the great white shark and the megamouth) and some are quite common (like the dogfish shark and bull shark). Sharks belong to the group of cartilagenous fish, the Elasmobranchii, that includes the sharks, rays, and skates.
 
Sharks play a vital role in our ecosystem as part of nature’s complex system of checks and balances. Known as apex predators, they are at the top of the food chain. Many sharks prey upon wounded and sick animals, keeping the populations of various species healthy and in balance, while others scavenge the ocean by feeding on dead animals or by filter feeding.
 
According to United Nation’s Food and Agriculture Organization (FAO) approximately 100 million sharks are killed each year. This does not include those caught as bycatch (non-targeted animals caught unintentionally and wasted), which is largely unreported. Many sharks also fall victim to finning, the practice of cutting shark’s dorsal, caudal and pectoral fins, then discarding the still-living shark into the sea to die. Sharks play a vital role in our ecosystem as part of nature’s complex system of checks and balances. Known as apex predators, they are at the top of the food chain. Many sharks prey upon wounded and sick animals, keeping the populations of various species healthy and in balance, while others scavenge the ocean by feeding on dead animals or by filter feeding.
 
Most sharks have no predators, but biological characteristics such as slow growth, late sexual maturity and low number of offsprings make sharks susceptible to almost any fishing pressure. Most species are either fished to capacity or overfished worldwide and for products like shark meat, fins and cartilage contribute to their decline.
 
In India, the bull shark is often called the Sundarbans or Ganges shark and it is found in the Ganges and Brahmaputra rivers of West Bengal and Assam in eastern India and adjoining Bangladesh.Sharks of the family Carcharhinidae are the most important group, dominating the fishery all over the world, and this applies equally in India.
 
 
SHARK ATTACKS
 
When some sharks (like the Great White or the Gray Reef shark) turn aggressive prior to an attack, they arch their back and throw back their head. This places their mouth in a better position for taking a big bite. They also move their tail more acutely (probably in preparation for a chase). Sharks do not normally attack people, and only about 25 species of sharks are known to attack people. Sharks attack fewer than 100 people each year. Many more people are killed by bees or lightning.
The sharks that are the most dangerous to people are the great white shark, the tiger shark, the bull shark, and the oceanic whitetip shark. The bull shark is the most frequent attacker of people as it swims in very shallow waters where people swim and is a very plentiful shark. Some of the other sharks that are known to have attacked people include the gray shark, blue shark, hammerhead shark, mako shark, nurse shark, lemon shark, blacktip reef shark, wobbegongs, sandtiger, spitting sharks, and the porbeagle. Some people believe that sharks mistake people (especially people swimming on surf boards) for seals and sea lions, some of their favorite foods.
 

References: Wikipedia, enchantedlearning.com

 

MY BLOG LIBRARY

For some of my articles visit:

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http://biodiversity-mohanpai.blogspot.com/
For some key chapters from my book “The Western Ghats”, please log on to:http://westernghats-paimohan.blogspot.com/
For detailed blog (6 Chapters from my book) on Mahadayi/Mandovi River Valley, please log on to:http://mohan-pai.blogspot.com/
For the book ‘The Elderly’ please log on to:
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http://oldagecare-paimohan.blogspot.com/
You can also access my blogs on Sulekha and WordPress
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http://mohanpai.sulekha.com/blog/posts.htm
For my book “The Flight of Gods – Hindu Temples & Shrines of Goa” please log on to:
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(Traditional Hindu Central Courtyard Houses of Goa)
email: mohanpai@hotmail.com

 
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Sunday Article: Seashells

Sunday article by Mohan Pai

About Seashells

The Sacred Conch of Lord Vishnu

Lord Vishnu, is said to hold a special conch, Panchajanya, that represents life, as it has come out of life-giving waters.

In India the sound of the conch is associated with the sacred syllable AUM, the first sound of creation. Conches that spiral clockwise are said to symbolize the expansion of infinite space. These conches belong to Lord Vishnu, the preserver god. Conches that spiral counterclockwise are said to defy the “laws of nature,” and belong to the destroyer/transformation god, Lord Shiva. The conch is one of the five principle weapons of Vishnu. Followers of Vishnu believe the conch shell was given to us to destroy all evil. Arjuna, the hero of India’s epic Mahabharata, blew a particularly powerful conch as a battle horn.

A Shankh shell (the shell of a Turbinella pyrum, a species in the gastropod family Turbinellidae) is often referred to in the West as a conch shell, or a chank shell. This shell is used as an important ritual object in Hinduism. The shell is used as a ceremonial trumpet, as part of religious practices, for example puja. The chank trumpet is sounded during worship at specific points, accompanied by ceremonial bells and singing. The warriors of ancient India blew conch shells to announce battle, as is described in the beginning of the war of Kurukshetra, in the Mahabharata, the famous Hindu epic. Lord Vishnu, is said to hold a special conch, Panchajanya, that represents life, as it has come out of life-giving waters.

A Hindu priest blowing a Shankh (a shell of Turbinella pyrum) during a puja.
 
 Shells are lovely natural objects, equals in beauty to any flower or butterfly, they are more than just pretty baubles found on beaches. They are the exterior skeletons (exoskeletons) of a group of animals called mollusks. The word “mollusk” means “soft-bodied;” an exterior skeleton is very important to these creatures, providing them with shape and rigidity, and also with protection, and sometimes camouflage, from predators.Mollusks are classified into major groupings according to the characteristics of their shells. Snails (Gastropoda) have a single shell which spirals outward and to one side as it grows. Most Cephalopoda (octopi and squid) have no shell, but the Chambered Nautilus of that group has a shell. This shell does coil, but it coils flatly, in a single plane. Tusk shells (Scaphopoda) also have a single shell, but it does not coil at all; it grows in a narrow and very slightly curved cone shape. Bivalves (Bivalvia), including oysters, clams, scallops and mussels, have two parts to their shells that enclose their tender bodies like the two halves of a hinged box. Chitons (Polyplacophora) are little armored tanks, with a row of eight overlapping plates protecting them. The Neopilina (Monoplacophora), are deep-sea “living fossils;” they have a single shell which hardly coils at all, but fits over their bodies like a protective cup.

While many sea animals produce exoskeletons, usually only those of molluscs (also spelt “mollusk”) are normally considered to be “sea shells”. The majority of shells are made of nacre, an organic mixture of outer layers of horny conchiolin (a scleroprotein), followed by an intermediate layer of calcium carbonate (CaCO3) as either calcite or aragonite in the form of platy crystals. Shells of the class Polyplacophora are made of a softer calcium carbonate compound called chiton. Mollusc shells (especially those formed by marine species) are very durable and outlast the otherwise soft-bodied animals that produce them by a very long time (sometimes thousands of years). They fossilise easily, and fossil mollusc shells date all the way back to the Cambrian period. Large amounts of shells may form sediment and become compressed into limestone.

1742 drawing of shells of the money cowry, Cypraea moneta

Shell money (money cowry)
 
Seashells have been used as a medium of exchange in various places, including many Indian Ocean and Pacific Ocean islands, also in North America, Africa and the Caribbean.The most common species of shells to be used as currency have been Cypraea moneta, the “money cowry”, and certain tusk shells or Dentalium, such as those used in North Western North America for many centuries. The Dutch East India Company, a major force in the colonization of the Indian and Pacific Oceans, amassed a large portion of its vast fortune via trading shell money of the species Cypraea moneta and Cypraea annulus, in exchange for commodities such as spices, exotic animals, and gemstones, all of which were considered valuable in Europe at the time.

Seashells in personal adornment
Seashells have been used as jewelry or in other forms of adornment since prehistoric times. Mother of pearl was historically primarily a seashell product although more recently some mother of pearl comes from freshwater mussels.Shell necklaces have been found in Stone Age graves as far inland as the Dordogne Valley in France. Seashells are often used whole and drilled, so that they can be threaded like beads, or cut into pieces of various shapes. Naturally-occurring, beachworn, cone shell “tops” (the broken-off spire of the shell, which often has a hole worn at the tip) can function as beads without any further modification. In Hawaii these natural beads were traditionally collected from the beach drift in order to make puka shell jewelry. Since it is hard to obtain large quantities of naturally-occurring beachworn cone tops, almost all modern puka shell jewelry uses cheaper imitations, cut from thin shells of other species of mollusk, or even made of plastic. Shells have been formed into, or incorporated into pendants, beads, buttons, brooches, rings, and hair combs, among other uses. The shell of the large “bullmouth helmet” sea snail, scientific name Cypraecassis rufa, was historically, and still is, used to make cameos. Mother of pearl from many seashells including species in the family Trochidae, Turbinidae, Haliotidae, and various pearly bivalves, has often been used in jewelry, buttons, etc. In London, Pearly Kings and Queens traditionally wear clothing covered in patterns made up of hundreds of “pearl buttons”, in other words, buttons made of mother-of-pearl or nacre.

Use of gastropod shells, specifically cowries, in traditional dress of the Kikuyu people of Kenya, Africa.

References: Wikipedia

MY BLOG LIBRARY
For some of my articles visit:
http://mohanpaiblogger.blogspot.com/
http://mohanpaisarticles.blogspot.com/
http://biodiversity-mohanpai.blogspot.com/
For some key chapters from my book “The Western Ghats”, please log on to:
http://westernghats-paimohan.blogspot.com/
For detailed blog (6 Chapters from my book) on Mahadayi/Mandovi River Valley, please log on to:
http://mohan-pai.blogspot.com/
For the book ‘The Elderly’ please log on to:
http://omashram.sulekha.com/blog/posts.htm
http://oldagecare-paimohan.blogspot.com/
You can also access my blogs on Sulekha and WordPress
https://mohanpai.wordpress.com/
http://mohanpai.sulekha.com/blog/posts.htm
For my book “The Flight of Gods – Hindu Temples & Shrines of Goa” please log on to:
http://flightofgods.sulekha.com/blog/posts.htm
http://flightofgods.blogspot.com/
For “Miscellany” log on to:
http://paimohan-mohanpai.blogspot.com/
(Traditional Hindu Central Courtyard Houses of Goa)

Sunday Article: The Fungi

Sunday article by Mohan Pai

 
 
The Fungi

 
Wild, edible mushrooms, especially the short-lived variety that blooms with the onset of monsoons is a much relished variety on the western coast.
The Fungi are large group of parasites and decomposers that include mushrooms, molds and yeasts. Fungi were once grouped along with plants but are now thought to be more closely related to animals and are treated as a separate kingdom.
A fungus is any member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. The Fungi are classified as a kingdom that is separate from plants and animals. One major difference is that fungal cells have cell walls that contain chitin, unlike the cell walls of plants, which contain cellulose. The discipline of biology devoted to the study of fungi is known as mycology, which is often regarded as a branch of botany, even though genetic studies have shown that fungi are more closely related to animals than to plants.Abundant worldwide, most fungi are inconspicuous because of the small size of their structures, and their cryptic lifestyles in soil, on dead matter, and as symbionts of plants, animals, or other fungi. They may become noticeable when fruiting, either as mushrooms or molds. Fungi perform an essential role in the decomposition of organic matter and have fundamental roles in nutrient cycling and exchange.
The fungi have long been used as a direct source of food, such as mushrooms and truffles, as a leavening agent for bread, and in fermentation of various food products, such as wine, beer, and soy sauce. Since the 1940s, fungi have been used for the production of antibiotics, and, more recently, various enzymes produced by fungi are used industrially and in detergents. Fungi are also used as biological agents to control weeds and pests. Many species produce bioactive compounds called mycotoxins, such as alkaloids and polyketides, that are toxic to animals including humans. Fungi can break down manufactured materials and buildings, and become significant pathogens of humans and other animals. Losses of crops due to fungal diseases (e.g. rice blast disease) or food spoilage can have a large impact on human food supplies and local economies.However, little is known of the true biodiversity of Kingdom Fungi, which has been estimated at around 1.5 million species, with about 5% of these having been formally classified.

Lichens are a symbiotic union between fungus and algae (or sometimes photosynthesizing bacteria). The algae provide nutrients while the fungus protects them from the elements. The result is a new organism distinctly different from its component species. Around 25,000 species of Lichens have been identified by scientists.
Medicinal mushrooms
The Kingdom Fungi includes some of the most important organisms, both in terms of their ecological and economic roles. By breaking down dead organic material, they continue the cycle of nutrients through ecosystems. In addition, most vascular plants could not grow without the symbiotic fungi, or mycorrhizae, that inhabit their roots and supply essential nutrients. Other fungi provide numerous drugs (such as penicillin and other antibiotics), foods like mushrooms, truffles and morels, and the bubbles in bread, champagne, and beer. Fungi also cause a number of plant and animal diseases: in humans, ringworm, athlete’s foot, and several more serious diseases are caused by fungi. Because fungi are more chemically and genetically similar to animals than other organisms, this makes fungal diseases very difficult to treat.
 
Edible mushrooms
Edible mushrooms are used extensively in cooking, in many cuisines (notably Chinese, European, and Japanese). Though mushrooms are commonly thought to have little nutritional value, many species are high in fiber and provide vitamins such as thiamine, riboflavin, niacin, biotin, ascorbic acid. Mushrooms are also a source of some minerals, including selenium, potassium and phosphorusMost mushrooms that are sold in market have been commercially grown on mushroom farms. The most popular of these, Agaricus bisporus, is generally considered safe for most people to eat because it is grown in controlled, sterilized environments, though some individuals do not tolerate it well.

The button mushroom (Agaricus bisporus), one of the most widely cultivated mushrooms in the world.

At present 3 mushrooms are being cultivated in India. These are : the white mushroom (Agaricus bisporus), the paddy-straw mushroom (Volvariella vovvacea) and the oyster mushroom (Pleurotus sajor-caju). Of these, A. bisporus is the most popular and economically sound to grow and is extensively cultivated throughout the world
Hallucinogenic mushrooms
Some mushrooms possess psychedelic properties. They are commonly known as “magic mushrooms” “mushies” or “shrooms” and are available in smart shops in many parts of the world, though some countries have outlawed their sale. Because of their psychoactive properties, some mushrooms have played a role in native medicine, where they have been used in an attempt to effect mental and physical healing, and to facilitate visionary states.
Amanita phalloides accounts for the majority of fatal mushroom poisonings worldwide.
 
Poisonous mushrooms
Of the many thousands of mushroom species in the world, only 32 have been associated with fatalities, and an additional 52 have been identified as containing significant toxins. By far the majority of mushroom poisonings are not fatal, but the majority of fatal poisonings are attributable to the Amanita phalloides mushroom.
 
Famous poisonings
Roman Emperor Claudius is said to have been murdered by being fed the death cap mushroom. Pope Clement VII is also rumored to have been murdered this way. Holy Roman Emperor Charles VI and Tsaritsa Natalia Naryshkina are believed to have died from eating the death cap mushroom. The composer Johann Schobert died in Paris, along with his wife and one of his children, after insisting that certain poisonous mushrooms were edible.

References: Wikipedia

MY BLOG LIBRARY
For some of my articles visit:
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http://mohanpaisarticles.blogspot.com/
http://biodiversity-mohanpai.blogspot.com/
For some key chapters from my book “The Western Ghats”, please log on to:
http://westernghats-paimohan.blogspot.com/
For detailed blog (6 Chapters from my book) on Mahadayi/Mandovi River Valley, please log on to:

Sunday Mail: About EHA – A Naturalist on the Prowl

Sunday, October 4, 2009

Hello friends,

Good morning. This Sunday, I thought, I could introduce EHA to my readers. EHA belongs to another era but his delightful writings and pen-and-ink sketches on nature and wildlife is a sheer joy to the reader. I have attached two of his complete works: 1. Concerning Animals 2. The Common Birds of India. You can download PDFs of some of his books FREE. Please log on to:
http://www.archive.org/search.php?query=creator%3A%22Aitken%2C%20Edward%20Hamilton%2C%201851-1909%22

Naturalist of the yore

Edward Hamilton Aitken (born 16 August 1851 in Satara, India, died 11 April 1909 Edinburgh was a humorist, naturalist and a writer especially on the wildlife of India. He was well known to Anglo-Indians by the pen-name of Eha. His higher education was obtained at Bombay and Pune. He passed M.A. and B.A. of Bombay University first on the list, and won the Homejee Cursetjee prize with a poem in 1880. From 1870 to 1876 he taught Latin at the Deccan College in Pune. He also knew Greek and was known to be able to read the Greek Testament without the aid of a dictionary.

He grew up in India and it was only later in life that he visited England for the first time and he found the weather of Edinburgh severe. EHA recorded his personal observations of the smallest creatures with a signature literary style. So remarkably absorbing were his descriptions that the great ornithologist Salim Ali says in his autobiography The Fall of a Sparrow, “Among my favourite and most admired naturalist writers are W.H.Hudson and E.H.Aitken (better known as EHA).” Salim Ali praises EHA for devoting extra attention to honing and polishing his “seemingly effortless essays.” Salim Ali also edited 3rd edition of his book The Common Birds of Bombay published as The Common Birds of India in 1915.

The finely tuned sense of humour and equally acute sense of drama in nature make the books a pleasurable read. The Sahib-style narrative lends a unique charm. EHA was undoubtedly a unique literary species himself. The little exaggerations quickly become unimportant, because there is an underlying charm to his stories. They contain the message of how much is happening around us, and how little we care to notice.

EHA’s books include:
The Tribes on my Frontier
An Indian Naturalist’s Foreign Policy (1883)
Behind the Bungalow (1889)
The Naturalist on the Prowl (1894)
The Common Birds of Bombay (1900)

Very best wishes,
Mohan Pai

MY BLOG LIBRARYFor some of my articles visit:
http://mohanpaiblogger.blogspot.com/
http://mohanpaisarticles.blogspot.com/
http://biodiversity-mohanpai.blogspot.com/
For some key chapters from my book “The Western Ghats”, please log on to:
http://westernghats-paimohan.blogspot.com/
For detailed blog (6 Chapters from my book) on Mahadayi/Mandovi River Valley, please log on to:http://mohan-pai.blogspot.com/
For the book ‘The Elderly’ please log on to:
http://omashram.sulekha.com/blog/posts.htm
http://oldagecare-paimohan.blogspot.com/
You can also access my blogs on Sulekha and WordPress
https://mohanpai.wordpress.com/
http://mohanpai.sulekha.com/blog/posts.htm
For my book “The Flight of Gods – Hindu Temples & Shrines of Goa” please log on to:
http://flightofgods.sulekha.com/blog/posts.htm
http://flightofgods.blogspot.com/
For “Miscellany” log on to:
http://paimohan-mohanpai.blogspot.com/
http://mohanpai.sulekha.com/blog/post/2009/09/traditional-hindu-central-courtyard-houses-of-goa.htm
https://mohanpai.wordpress.com/2009/09/23/traditional-hindu-central-courtyard-houses-of-goa/
(Traditional Hindu Central Courtyard Houses of Goa)


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