Coral Reefs - 'Living organisms'

Sunday article by Mohan Pai

Coral Reefs

"The Living Organisms"

Some of the biodiversity of a coral reef, in this case the Great Barrier Reef, Australia

Called “rainforests of the sea”, coral reefs are living organism and the oldest, most productive ecosystems on earth.

Existing for more than 500 million years, Corals are marine organisms from the class Anthozoa and exist as small sea anemone-like polyps, typically in colonies of many identical individuals. The group includes the important reef builders that are found in tropical oceans, which secrete calcium carbonate to form a hard skeleton.

A coral "head", commonly perceived to be a single organism, is formed from myriads of individual but genetically identical polyps, each polyp only a few millimeters in diameter. Over thousands of generations, the polyps lay down a skeleton that is characteristic of their species. An individual head of coral grows by asexual reproduction of the individual polyps. Corals also breed sexually by spawning, with corals of the same species releasing gametes simultaneously over a period of one to several nights around a full moon.

Although corals can catch small fish and animals such as plankton using stinging cells on their tentacles, these animals obtain most of their nutrients from photosynthetic unicellular algae called zooxanthellae. Consequently, most corals depend on sunlight and grow in clear and shallow water, typically at depths shallower than 60 metres (200 ft). These corals can be major contributors to the physical structure of the coral reefs that develop in tropical and subtropical waters, such as the enormous Great Barrier Reef off the coast of Queensland, Australia. Other corals do not have associated algae and can live in much deeper water, with the cold-water genus Lophelia surviving as deep as 3,000 metres (9,800 ft). Examples of these can be found living on the Darwin Mounds located north-west of Cape Wrath, Scotland. Corals have also been found off the coast of Washington State and the Aleutian Islands in Alaska.Corals coordinate behaviour by communicating with each other.
 
Globally, coral reefs are under threat from climate change, ocean acidification, overuse of reef resources, and harmful land-use practices. High nutrient levels such as those found in runoff from agricultural areas can harm reefs by encouraging excess algae growth.
 
Formations

Coral reefs can take a variety of forms, defined in following:

Fringing reef – a reef that is directly attached to a shore or borders it with an intervening shallow channel or lagoon.

Barrier reef – a reef separated from a mainland or island shore by a deep lagoon (Great Barrier Reef).

Patch reef – an isolated, often circular reef, usually within a lagoon or embayment.

Apron reef – a short reef resembling a fringing reef, but more sloped; extending out and downward from a point or peninsular shore.

Bank reef – a linear or semi-circular shaped-outline, larger than a patch reef.

Ribbon reef – a long, narrow, somewhat winding reef, usually associated with an atoll lagoon.

Atoll reef – a more or less circular or continuous barrier reef extending all the way around a lagoon without a central island.

Table reef – an isolated reef, approaching an atoll type, but without a lagoon.

Distribution
Coral reefs are estimated to cover 284,300 square kilometers, with the Indo-Pacific region (including the Red Sea, Indian Ocean, Southeast Asia and the Pacific) accounting for 91.9% of the total. Southeast Asia accounts for 32.3% of that figure, while the Pacific including Australia accounts for 40.8%. Atlantic and Caribbean coral reefs only account for 7.6%.
 
 

Location map of coral reefs

Locations of coral reefs.
Although corals exist both in temperate and tropical waters, shallow-water reefs form only in a zone extending from 30°N to 30°S of the equator. Tropical corals do not grow at depths of over 50 m (165 ft). Temperature has less of an effect on the distribution of tropical coral, but it is generally accepted that they do not exist in waters below 18 °C., and that the optimum temperature is 26-27° Celsius for most coral reefs. The reefs in the Persian Gulf however have adapted to temperatures of 13° Celsius in winter and 38° Celsius in summer. Deep water coral is more still exceptional since it can exist at greater depths and colder temperatures. Although deep water corals can form reefs, very little is known about them.

Famous coral reefs and reef areas of the world include:

The Great Barrier Reef - largest coral reef system in the world, Queensland, Australia;

The Belize Barrier Reef - second largest in the world, stretching from southern Quintana Roo, Mexico along the coast of Belize to the Bay Islands of Honduras.

The New Caledonia Barrier Reef - second longest double barrier reef in the world, with a length of about 1500 km.

The Andros, Bahamas Barrier Reef - third largest in the world, following the east coast of Andros Island, Bahamas, between Andros and Nassau.


The Red Sea Coral Reef - located off the coast of Israel, Egypt and Saudi Arabia.

Pulley Ridge - deepest photosynthetic coral reef, Florida

Numerous reefs scattered over the Maldives

Ghe Raja Ampat Islands in Indonesia's West Papua province offer the highest known marine diversity.

                                                                    Anatomy of Coral Polyp

References: Wikipedia

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Sunday Article: The House Crow

Sunday article by Mohan Pai

The House Crow
Corvus splendens

Photo courtesy: J. M. Garg

In India, the crow is considered a spirit of the ancestors. During Shraddha or death ceremony pinda (food) is offered and is considered accepted only if a crow arrives and eats it.

 
The house crow is a widespread resident of India and has a special place in Hindu society. During death ceremonies (shraddha) and Pitru Paksha, the practice of offering food or pinda to crows is still in vogue since crows are believed to represent our ancestors.
 
The House Crow, also known as the Colombo Crow is a common bird of the Crow family that is of Asian origin but now found in many parts of the world, where they arrived assisted by shipping. It is between the Jackdaw and the Carrion Crow in size (40 cm in length) but is relatively slimmer than either. The forehead, crown, throat and upper breast are a richly glossed black, whilst the neck and breast are a lighter grey-brown in colour. The wings, tail and legs are black. There are regional variations in the thickness of the bill and the depth of colour in areas of the plumage.
 
Distribution and habitat


It has a widespread distribution in southern Asia, being native to Nepal, Bangladesh, India, Pakistan, Sri Lanka, Maldives and Laccadive Islands, South West Thailand and coastal southern Iran. It has been introduced to East Africa around Zanzibar (around 1897[3]) and Port Sudan, and arrived in Australia via ship but has up to now been exterminated. Recently it has made its arrival in Europe, and has been breeding in the Hook of Holland since 1998. It is associated with human settlements in all of its range, from small villages to large cities.

Due to a human population explosion in the areas it inhabits, this species has also proportionately multiplied. Being an omnivorous scavenger has enabled it to thrive in such circumstances.
 
 

House Crow - distribution

The invasive potential for the species is great all over the tropics. It has as yet not established in the New World. This species is able to make use of resources with great flexibility and appears to be associated with humans and no populations are known to exist independently of human

Size: 42 cm Weight: 250-350 gm

Identification: Plumage is glossy black, except for the nape, sides of the head, upper back and breast, which are grey. Bill, legs, and feet also black. Sexes alike.

Food: Omnivorous. Diet includes seeds, fruit, grain, nectar, berries, bird’s eggs, nestlings, mammals, reptiles, amphibians, fish, insects, wide range of carrion.It is a highly opportunistic bird and given its omnivorus diet, it can survive on anything that is edible.

Call: Normal call a harsh qua qua or a nasal kaan kaan. It also has a couple of softer calls when resting or during courtship.

Habits: Highly vocal, gregarious birds, seemingly unafraid of humans. Aggressive, will attack and chase off any large bird of prey. Birds have been reported taking food from school children and killing chicks of domestic fowls. Breeding pairs will repeatedly dive bomb humans near the nest.

Habitat: Wholly dependent on human habitation; consequently found in villages, towns, and cities throughout its range. Resorts to altitudinal and seasonal local movements in colder northern areas in winter. Replaced by Large-billed Crows and Jungle Crows in mountains and forests respectively.

Breeding: Solitary nester except in areas of high population density. Will use trees, buildings, or other artificial structures for rough stick nest lined with coir or other fibre. Four to five pale blue-green eggs, speckled with brown. Breeding season March through July. Incubation 16–17 days; fledging 21–28 days.

Status: Not threatened. Abundant in its range to the point of being a pest and a threat to other bird species.

Photo courtesy Muhammad Mahdi Karim

References: Wikipedia, birding.in

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Sunday Article: Vanishing Species: Shark

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

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Sunday article: About 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


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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

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http://mohanpai.sulekha.com/blog/posts.htm
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http://mohanpai.sulekha.com/blog/post/2009/09/traditional-hindu-central-courtyard-houses-of-goa.htm
http://mohanpai.wordpress.com/2009/09/23/traditional-hindu-central-courtyard-houses-of-goa/
(Traditional Hindu Central Courtyard Houses of Goa)

Sunday article: 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
http://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
http://mohanpai.wordpress.com/2009/09/23/traditional-hindu-central-courtyard-houses-of-goa/
(Traditional Hindu Central Courtyard Houses of Goa)

Indian Spiders

Sunday article by Mohan Pai

Indian Spiders

Arachnids

Pic courtesy: Sandilya Theurkauf

Cobwebs of deception

In the gathering light of dawn, an orb-web spider sits motionless in the centre of its web. The web is one of nature’s most ingenious traps - woven from at least six types of silks and constructed with mathematical precision. But spiders are so short-sighted that they can barely see their webs. Instead they build them by touch, and instinct guides their every move. Weight for weight, spider’s silk is stronger than steel. Even so, webs soon get damaged and need to be repaired. When the damage gets too great, a spider instinctively knows to give up on repair work, and start afresh. It eats up the old web so that it can digest and recycle the silk. Each kind of spider always makes exactly the same kind of web.

‘Come into my parlour...’

Spiders are generally regarded as predatory. The best-known method of prey capture is by means of sticky webs. Varying placement of webs allows different species of spider to trap different insects in the same area, for example flat horizontal webs trap insects that fly up from vegetation underneath while flat vertical webs trap insects in horizontal flight. Web-building spiders have poor vision, but are extremely sensitive to vibrations. Females of the water spider Argyroneta aquatica build underwater "diving bell" webs which they fill with air and use for digesting prey, molting, mating and raising offspring. They live almost entirely within the bells, darting out to catch prey animals that touch the bell or the threads that anchor it. A few spiders use the surfaces of lakes and ponds as "webs", detecting trapped insects by the vibrations that these cause while struggling. Spiders (order Araneae) are air-breathing chelicerate arthropods that have eight legs, and chelicerae modified into fangs that inject venom. They are the largest order of arachnids and rank seventh in total species diversity among all other groups of organisms. Spiders are found world-wide on every continent except for Antarctica, and have become established in nearly every ecological niche with the exception of air and sea colonization. As of 2008, approximately 40,000 spider species, and 109 families have been recorded by taxonomists. However, there has been confusion within the scientific community as to how all these genera should be classified, as evidenced by the over 20 different classifications that have been proposed since 1900.

Spiders are abundant and widespread in almost all ecosystems and constitute one of the most important components of global biodiversity. Spiders have a very significant role to play in ecology by being exclusively predatory and thereby maintaining ecological equilibrium. Many spiders feed on noxious insects like houseflies and mosquitoes which are vectors of human diseases. A large number of spiders are found in agricultural fields and thus play an important role in controlling the population of many agricultural pests. Despite this importance, spiders are largely neglected mainly due to ignorance and fear and the subsequent dislike for them. Although more than 1400 species (quite a number is endemic) have been described from India (and many more to be documented), the study on the taxonomy, biology and ecology of Indian spiders remains neglected.

Anatomically, spiders differ from other arthropods in that the usual body segments are fused into two tagmata, the cephalothorax and abdomen, and joined by a small, cylindrical pedicel. Unlike insects, spiders do not have antennae. In all except the most primitive group, the Mesothelae, spiders have the most centralized nervous systems of all arthropods, as all their ganglia are fused into one mass in the cephalothorax. Unlike most arthropods, spiders have no extensor muscles in their limbs and instead extend them by hydraulic pressure.Their abdomens bear appendages that have been modified into spinnerets that extrude silk from up to six types of silk glands within their abdomen. Spider's webs vary widely in size, shape and the amount of sticky thread used. It now appears that the spiral orb web may be one of the earliest forms, and spiders that produce tangled cobwebs are more abundant and diverse than orb-web spiders. Spider-like arachnids with silk-producing spigots appear in the Devonian period about 386 million years ago, but these animals apparently lacked spinnerets.

True spiders have been found in Carboniferous rocks from 318 to 299 million years ago, and are very similar to the most primitive surviving order, the Mesothelae. The main groups of modern spiders, Mygalomorphae and Araneomorphae, first appear in the Triassic period, before 200 million years ago. Most known species are predators, mostly preying on insects and on other spiders, although a few large species also take birds and lizards. Spiders use a wide range of strategies to capture prey: trapping it in sticky webs, lassoing it with sticky bolas, mimicking the prey to avoid detection, or running it down. Spiders' guts are too narrow to take solids, and they liquidize their food by flooding it with digestive enzymes and grinding it with the bases of their pedipalps, as they do not have true jaws.Male spiders identify themselves by a variety of complex courtship rituals to avoid being eaten by the females. Males of most species survive a few matings, limited mainly by their short life spans. Females weave silk egg-cases, each of which may contain hundreds of eggs. Females of many species care for their young, for example by carrying them around or by sharing food with them. A minority of species are social, building communal webs that may house anywhere from a few to 50,000 individuals. Social behavior ranges from precarious toleration, as in the aggressive widow spiders, to co-operative hunting and food-sharing. Although most spiders live for at most two years, tarantulas and other mygalomorph spiders can live up to 25 years in captivity.While the venom of a few species is dangerous to humans, scientists are now researching the use of spider venom in medicine and as non-polluting pesticides. Spider silk provides a combination of lightness, strength and elasticity that is superior to that of synthetic materials, and spider silk genes have been inserted into mammals and plants to see if these can be used as silk factories. As a result of their wide range of behaviors, spiders have become common symbols in art and mythology symbolizing various combinations of patience, cruelty and creative powers.

References: Wikipedia, Spider information

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
http://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
http://mohanpai.wordpress.com/2009/09/23/traditional-hindu-central-courtyard-houses-of-goa/
(Traditional Hindu Central Courtyard Houses of Goa)