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Subject: ‘Fish’

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Some animals lay dozens of eggs then simply disappear

Posted in Animals, Fish, Insects, Nature, Wildlife on Monday, 24 February 2014

This edited article about animals first appeared in Look and Learn issue number 564 published on 4 November 1972.

Turtles and fish,  picture, image, illustration
Green turtles and tropical fish

The green turtle lives in tropical seas. Each year the females come ashore on sandy beaches to lay their eggs. Once the green turtle was very common but it has now disappeared from many of its old haunts and in others it is rare. This is because its eggs and flesh are good to eat. Part of the body called calipee, is used for making turtle soup.

Before men found where the turtles laid their eggs the females could come ashore in safety. A full grown green turtle is over 3 feet long and weighs 300-400 lbs. It is protected by thick shell so that it has little to fear from flesh-eating animals. This is a good thing because a turtle is very clumsy on land. Its flippers are excellent for swimming but not very good for dragging its heavy body up the beach. Every few feet it has to stop for breath, until it gets above the high tide mark. Here the turtle digs a hole in the sand and lays 100 white eggs like table tennis balls. When she has finished laying, she fills in the hole and returns to the sea.

Each year the turtle lays five or more clutches of 100 eggs. Turtles live for many years and each female lays thousands of eggs in her lifetime. For the numbers of green turtles to stay steady it is only necessary for two of each turtle’s offspring to grow up and replace their parents. So if a turtle lays thousands of eggs it seems strange that they should have become so rare. The reason is that, even without men taking some of the eggs and killing the adults, the turtles face many dangers. They have to lay so many eggs just to make sure that enough baby turtles grow up to take over from the parents when they die.

Before the eggs have even hatched, the new generation of turtles is in danger. Wild dogs or large monitor lizards come down to the shore and dig up the nests. The whole clutch of 100 eggs can be wiped out in one swoop. But greater dangers await the baby turtles when they hatch out and set out to sea.

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Natural life in the racing torrents and waterfalls

Posted in Animals, Birds, Fish, Nature, Wildlife on Monday, 24 February 2014

This edited article about wildlife first appeared in Look and Learn issue number 563 published on 28 October 1972.

Salmon leaping falls,
Salmon leaping torrents and waterfalls

In the hilly and mountainous parts of the country the streams are torrents which come tumbling downhill, splashing over rocks and pouring over waterfalls. The movement of the water is eye-catching in what is often an otherwise desolate scene. Over the years, the streams have carved gullies and ravines in the hillsides for small trees and bushes to find shelter from the wind. Waterfalls are especially spectacular, where a wall of foaming water crashes in to a pool at the bottom.

These streams and waterfalls may look pretty but they do not appear at first sight to be good places for animals to live. A paddle in the water shows up the disadvantages. The water is icy cold and quickly numbs the feet, while the current is often strong enough to make standing difficult. In the fiercest mountain streams the boulders may be dislodged and hurled down-stream.

Yet, as in other inhospitable places, from hot volcanic springs to the ocean bed, there are certain animals which make a living in torrents. There are some advantages for small animals. The foaming water is full of oxygen for breathing and the water carries food which only needs to be picked up as it goes past. Two things are needed, however. Torrent animals must be able to withstand cold and they must be able to cling tightly to the rocks by means of claws or suckers so that they do not get swept away.

In the British Isles there are several small animals which live in fast-flowing streams. They are mostly the larvae of insects. The adults do not live in the streams but they come there to lay their eggs.

Mayflies are common insects which can be seen flying near water. They lay their eggs in the water and these hatch into larvae called nymphs. The nymphs have three “tails” at the tip of the abdomen, as do the adults, and there are two rows of feathery gills on the sides of the body. Mayfly nymphs can be found in many ponds and streams. Some burrow in mud near the bank, others creep amongst the water weed, but a few can be seen in fast streams. Nymphs of the mayfly called Ecdyonurus have broad, flat bodies and cling to stones so that the water rushes past them. The legs are also flattened and are held at an angle so that the force of the water pushes them against the stone. A relative of Ecdyonurus, called Rhithrogena, has turned one of its pairs of gills into a sucker to help it cling to stones.

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Fish supplement their oxygen intake in many ingenious ways

Posted in Animals, Fish, Nature, Wildlife on Thursday, 20 February 2014

This edited article about marine life first appeared in Look and Learn issue number 560 published on 7 October 1972.

Climbing Perch,  picture, image, illustration
Climbing Perch by K Lilly

By now, there are very few of us who are unaware of the serious problems of pollution, of the countryside, of rivers, of oceans and even of the air around us. To put the situation simply, we are producing many substances that are poisons and such large quantities are being produced that populations of living things run the danger of being wiped out. Some of these poisons, or pollutants, are easily recognised as being dangerous. Factory chimneys pour out acid gases; pesticides directed at harmful insects accumulate in the bodies of insect-eating birds; and chemical wastes from factories are pumped into rivers. The effects of these forms of pollution are often only too obvious, but rivers and lakes are subject to a form of pollution which can be caused by fertilisers.

In the heart of the country, where the only industry is agriculture, the water of rivers and lakes appears as fresh as it ever was. There are plenty of water plants and it would appear that aquatic animals should be thriving. But, the greater the growth of the water weed, the fewer fishes, insects, snails, crustaceans and other animals are able to survive. The problem is that the water weed, particularly forms of lower plants called algae, is removing the oxygen from the water as it decays. Without oxygen, the animals living in the water suffocate and among the first to disappear are members of the trout family and the crayfish. Other species can survive with a smaller supply of oxygen but if the process continues, the water becomes empty of life. Even the plants die and the river or lake becomes discoloured and stinking. At this stage bacteria take over and produce hydrogen sulphide (rotten-egg gas) and other noxious chemicals.

The cause of these lifeless waters is the application of large quantities of artificial fertilisers to cultivate fields. The fertilisers drain off the fields where they have been spread to increase the crops and accumulate in rivers and streams. The first result of a massive does of fertiliser is an enormous increase in water weed. In effect, the water is being fertilised in the same way as the soil on the fields. When the weed dies, it sinks to the bottom and decays. It forms a layer of slime and the process of decay uses up the oxygen in the water, so depriving the animals of the oxygen they need.

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A Siamese Fighting Fish will attack any rival it sees

Posted in Animals, Fish, Nature, Wildlife on Wednesday, 19 February 2014

This edited article about fish first appeared in Look and Learn issue number 557 published on 16 September 1972.

Siamese Fighting Fish,  picture, image, illustration
Siamese Fighting Fish

The two fish circled each other warily. Then with a lightning thrust, one of them lunged at the other’s fin and savagely bit into it, as its opponent twisted and turned in a vain attempt to escape.

These two fish were Siamese Fighting Fish which, size-for-size, are among the most ferocious fish in the sea. Although only 2 ½ inches long, the male Siamese Fighting Fish are very aggressive towards one another. A male will even try to fight its own image in a mirror.

When two males are put in an aquarium, their colours brighten and they take up fighting positions. Their fins are erected and with lightning speed they attack. They aim for each other’s fins and at the end of the battle, one may have some of its fins bitten down to bloody stumps. Sometimes they meet in a head-on clash, with jaws interlocked.

Contests between male fighting fish are extremely popular in Siam and the Siamese have for centuries put male fighters together in tanks and then staked enormous sums of money on the result of the fight. They have bred champions which fight for as long as ten hours, although wild fighting fish rarely keep up their fight for more than 15 minutes.

Before the law stopped this gambling, a Siamese would, after having lost all he possessed, even stake his own liberty as the result of a fight, agreeing to serve as a gardener or house boy to the owner of the winning fish, for a period of months or even years.

The Siamese Fighting Fish are favourite fish for aquariums in Europe. The fish are brilliantly coloured and their owners breed them for their gorgeous appearance rather than for their fighting qualities. A male fighter can be kept safely with other species in an aquarium because, like a human boxer, the Siamese Fighting Fish scorns to attack a non-professional.

The “Talking Fish” was a performing seal called Jenny

Posted in Animals, Fish, Historical articles, History, Leisure, London, Oddities on Tuesday, 18 February 2014

Talking fish,  picture, image, illustration
The Talking Fish

The Victorians were fascinated by natural oddities, and exhibitions of Unnatural Wonders and Freaks of Nature were very popular. In The Times of April, 1859, there appeared an advertisement for one such event: “THE TALKING AND PERFORMING FISH will arrive at 191 Piccadilly, early in May. Complimentary cards to naturalists and gentlemen of the press will be issued for private performances three days before public exhibition.” This turned out not to be a fish but a pet seal called Jenny, which had been taught by her keeper to perform various tricks and make suitably speech-like sounds when required. Charles Darwin’s On the Origin of Species was published in November of the same year, 1859, and the subsequent interest in evolution would give rise to many bizarre ‘entertainments’ mocking the scientific attempts to find human characteristics in the animal kingdom.

Many more pictures relating to London entertainments can be found at the Look and Learn picture library.

The deadly piranha fish can destroy almost anything

Posted in Animals, Fish, Nature, Wildlife on Monday, 17 February 2014

This edited article about fish first appeared in Look and Learn issue number 555 published on 2 September 1972.

Piranha fish,  picture, image, illustration
Piranha

In the freshwater rivers of South America lives the most ferocious and savage of all creatures. This is the deadly piranha fish which has an insatiable greed for flesh and blood.

Any unfortunate animal, whatever its size, which falls into a piranha-infested river will have absolutely no chance of survival.

A human being is another of the piranha’s unfortunate victims. Within a matter of minutes this savage fish can reduce a fully grown man to a mere skeleton. For piranha fish hunt in scores, often hundreds, and instantly attack to rush in for the kill and slice their victim into tiny shreds.

With their powerful jaws and large serrated, needle-sharp teeth, these deadly fishes can literally rip an animal apart with one fast snap. Even if a victim manages to drag itself ashore the piranha will still cling to its body stabbing and biting to the last.

There is one instance recorded of a horse falling into a river where some aggressive piranhas swam and within five minutes the horse, including its saddle were destroyed.

But the piranha’s actual danger to man does vary according to what species it belongs to, and in what conditions it lives. In areas far away from native villages a man can usually swim in safety in piranha-infested rivers. On the other hand in the rivers near villages where rubbish and the carcases of animals are dumped the piranhas soon become quite fearless and rush to attack anything which disturbs the water.

Some species of piranha fish have been kept in aquariums but usually, with little success. If two are placed together for any length of time one will almost always be killed by the other. Five or six in a group may get along fairly well for a short time, but after a while they can become aggressive and all but the victor are killed.

If, though, 10 or 12 are placed in the same tank, and if they are well fed, they may become less aggressive and will not attack each other.

The sea monster of legend was probably a squid

Posted in Animals, Fish, Historical articles, History, Legend, Sea on Friday, 14 February 2014

This edited article about legendary sea monsters first appeared in Look and Learn issue number 551 published on 5 August 1972.

Sailors with sea monster,  picture, image, illustration
The mysterious monster was disabled by sailors who managed to rope it and drag it aboard, by Graham Coton

Monsters have been with us from the earliest times, shaking the ground with their heavy tread, or scorching the grass with their fiery breath as they lumber through the pages of every country’s mythology. Almost all of them stemmed from the superstitious, simple minds of primitive people who had seen something which they literally magnified into a monster when they reported it to their equally scared listeners. We know, for an instance, that the legend of the unicorn owes its existence to someone having seen a rhinoceros.

But what about the great sea monster which countless people have claimed to have seen. Is this also merely a myth? Many people have certainly dismissed it as such, forgetting that myths are stories whose origins are mostly shrouded in the mists of the past. The sea monster, on the other hand, was seen as late as the latter part of the 19th century by hard-headed sea captains whose lives often depended on the accuracy of their eyesight.

It has to be confessed, of course, that the sea monster has been with us for a remarkably long time, which does pose the question that if it had been constantly breeding in the ocean throughout the centuries, why had not one of them ever been hauled aboard?

The early Roman writer, Pliny, mentions one of these creatures which according to him had a head as big as a cask, and tentacles more than 30 feet long. But as he also claims that it was seen to come ashore and then climb a fence, one may, without much difficulty, dismiss this as one of his more imaginative essays.

On the surface, at least, a more reliable writer was Bishop Pontoppidon, a Norwegian historian who lived in the 18th century. The Bishop had heard tales of a sea monster called the Kraken, but he had openly dismissed them as sheer nonsense. Later, after sifting carefully through all the accounts he had received from the local fishermen, he decided that the sea monster did exist. It was of an enormous size and with horns, the Bishop solemnly informed his readers. It also had tentacles as high as the masts of a large vessel, and these were so powerful that if they were to lay hold of the largest man of war they would pull her down to the bottom.

From this description it would seem that, like Pliny, we cannot take the good Bishop too seriously. Especially when we bear in mind that he had never seen a sea monster himself. Is it possible that the local fishermen were pulling his leg?

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The hunter’s ingenuity in the animal kingdom

Posted in Animals, Fish, Nature, Wildlife on Wednesday, 29 January 2014

This edited article about animals first appeared in Look and Learn issue number 532 published on 25 March 1972.

Archer fish,  picture, image, illustration
Archer fish

The Greek and Roman fishermen knew that a particular fish gave out what they described as a “poisonous flow” from its veins that spread through the water, crept up the line and down the rod, and congealed the blood in their hands. The Romans even used it to cure gout. We know this fish as the electric ray, a relative of the skate.

The Ancient Egyptians painted a fish on the walls of their tombs 5,000 years ago. It is the fish we now call the electric catfish. The Arabs called it “ra’ad, the shaker,” and used it to treat ailments that we today treat by electrotherapy. It can discharge 350 volts.

So all that time ago, people were coming into contact with electricity, even using it medically, without knowing there was such a thing.

These fishes, and a number of others since discovered, use electric shocks as a defence weapon against enemies, and also to stun their prey. The most famous is the electric eel of the rivers of South America. Most of the muscles in the body of this nine foot long eel have been converted to electric organs. It can generate from 370 to 550 volts, killing fishes and frogs on which the eel feeds and even stunning a horse wading into the water.

Beside such refined and sophisticated weapons, the teeth and claws used by other animals seem almost primitive. They are even more so when compared with the weapon used by the pistol shrimp, two inches long, that stuns its prey by the sound made by one of its claws. This shrimp lives on the coast of California where it burrows into the sand, lying there with its antennae sticking out ready to sense a passing fish. One of its claws is at least half the size of its body. At the end is a joint that can be cocked and brought down on the tip of the claw with a sound like that of the hammer of an old pistol. In fact, it looks exactly like such a hammer.

When a pistol shrimp is kept in an aquarium, the click of its hammer can be heard all over the laboratory. It has been known to shatter a large glass jar near the aquarium, and anyone holding a pistol shrimp when it snaps its pistol feels a stinging sensation in his hand. Appropriately, one pistol shrimp has been given the scientific name Crangon bellimanus, the shrimp with the war hand.

Even more animals use sound to intimidate a foe. A spiny lobster has noise-making apparatus at the base of each antenna. When an enemy gets too close, it makes a grating noise, though what effect this has on its enemies we have yet to find out. Perhaps we get a clue from the way shrews settle their differences, with a squeaking match. Whether they hurt each other with it has never been investigated.

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Angel fish turn nasty when they see defenceless small fry

Posted in Animals, Fish, Nature, Wildlife on Tuesday, 3 December 2013

This edited article about fish first appeared in Look and Learn issue number 474 published on 13 February 1971.

Tropical fish, picture, image, illustration
Blue Angel fish (top) anong other tropical fish

Angelfish are probably the most popular of all the fishes kept in tropical aquaria. The reason for this is perhaps obvious. Not only are they very exotic and unusual in shape, they are also beautifully marked and extremely graceful. The most common of the tropical freshwater angelfish is Pterophyllum scalare.

But a peculiarity of these fish is that they are remarkably good parents.

Anyone who has ever kept a tropical aquarium knows that most adult fish are apt to eat their young. This is not so of angelfish. Both the male and the female are good parents and the male is particularly loving.

It is he who guards the eggs and, after they hatch, it is he who cares for the young. He does this by taking the babies into his mouth and then spraying them out on to any available leaves. This gives the babies aeration and also removes any fungus from them. Some, of course, go to the bottom and are caught up in the mud and die, but a great many are saved by the loving care of the father.

Some of the most popular angelfish belong to the Cichlidae family and are natives of South America, being found in the Amazon.

Their colouring is highly protective, since the black stripes across their bodies make very good camouflage.

Nowadays, a number of different varieties have been bred. Some are completely black and others are marbled, black and white.

They are usually kept quite safely in a community aquarium, provided there are no very small fishes present. Many members of the Cichlidae family, however, are rather vicious and will attack other species unmercifully.

But even angelfish are not very friendly when they have babies to protect!

Puffer fish contain the dangerous poison tetrodotoxin

Posted in Animals, Fish, Nature, Wildlife on Monday, 2 December 2013

This edited article about fish first appeared in Look and Learn issue number 473 published on 6 February 1971.

Funny fish, picture, image, illustration
Puffer fish (top) among other unusual fish

In the tropical waters around the world there are many fantastic fish. Some have so many glorious colours that they would dazzle even the most gaily dressed people.

Some fish, however, are not renowned for their colour but for their amazing ability to blow themselves up like balloons in a very short space of time, like the Puffer. An expanded Puffer thrown back into the water will float upside down for several minutes, for it takes quite a long time to expel the air.

Why does the Puffer do this? The answer to that is that it is the Puffer’s only means of protection, apart from the dappled appearance of some members of its family, which acts as camouflage in certain circumstances. By suddenly changing its shape the Puffer can confuse the enemy, and it is likely that the captor may drop it. Also, if the Puffer in its normal state appears to be an appropriate meal-sized fish for a predator, in its puffed-up condition it may be just that little bit too big to swallow! As well as sucking in air it is also capable of swallowing water, which enables it to protect itself in its natural surroundings.

The Chequered Puffer can grow to a maximum of 36 in., although most are fully grown at half this size. Despite the fact that their bodies contain a deadly poison, tetrodotoxin, they are eaten with great relish in Japan, after the poison has been removed. The dish for which they are prepared is called fugu, and cooks must have special training in a licensed fugu school to do this, for food poisoning as a result of eating improperly-prepared fugu is frequently fatal.

The Porcupine Fish is really a Puffer with spines added. The spines, which stand away from the body when the fish swallows air or water, provide extra protection.