This edited article about diving originally appeared in Look and Learn issue number 704 published on 12 July 1975.

Diver and sharks filmed underwater

Fright paralysed Lotte Hass. For a moment, she hung suspended in the warm tropical waters, staring in disbelief at the amazing creature which was swimming towards her.

It was like nothing she had ever seen before, for it is not everyone’s lot to come face to face with a manta ray. And this one had huge flippers which gave it a wingspan of over fifteen feet. Its features were frighteningly equipped with two large lobes which it used to shovel food into its mouth.

Lotte felt particularly defenceless in her skin-diving suit and face mask because all she had for her protection was a harpoon.

But she had been asked to swim close to the creature for a film about underwater life being made by her husband, Hans Hass, whose films have been shown on television in Britain. He had assured her that the manta ate nothing but tiny marine creatures called plankton, and had no teeth at all.

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This edited article about nature’s smallest animals and plants originally appeared in Look and Learn issue number 699 published on 7 June 1975.

Pygmy shrews

Our smallest native bird is the Goldcrest, but this is a giant compared with the world’s smallest bird the tiny Bee Humming Bird, found in Cuba and Ecuador. It gets its name because it is no bigger than a large bumble bee.

Its wings beat so fast that they are just a blur when it hovers in front of a tropical flower, its long beak dipping into the nectar in quest of nourishment. The adult females are slightly larger than the males.

Our smallest animal is the Pygmy Shrew, at two and one quarter inches, (57 mm), slightly smaller than the long-tailed Harvest Mouse. Even smaller is the Etruscan Shrew with a body length of only 1 and a half inches (38 mm) and reputed to be the smallest animal in the whole world.

Apart from animals, there are also a great number of microscopic insects. Some of these are so minute that they are scarcely visible to the naked eye.

The Dwarf Beetle, for instance, is small enough to pass through the eye of a small needle. The Small Blue Butterfly, less than 1 and a quarter inches (about 25 mm), across the wings, is the smallest British butterfly.

Unlike most of its kindred, it is only on the wing during the months of May and June.

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This edited article about vitamins originally appeared in Look and Learn issue number 690 published on 5 April 1975.

A poster from the 1940s promoting healthy food consumption

Doctors were puzzled. In Britain’s smoky industrial cities, children were suffering from a disease which made them very ill and left them with bent bones.

But in the fishing ports, the youngsters seemed miraculously free from this ailment. What was the reason? In time, the doctors found the answer.

The fishermen’s children were eating bread dipped in fish oil, and it was the oil which was keeping them free from the dreadful illness, called rickets, which was spoiling the health of the city children.

Rickets is caused by a lack of calcium which is necessary for the building of strong bones. This cannot be obtained unless there is vitamin D in our food. Fish oil is rich in vitamin D, and that is why the fishermen’s children who ate it were fit and the city children, who were denied it, were sickly.

If we eat a balanced diet, we will get all the things we need to be healthy, including all the substances called vitamins, from the Latin word vita for “life”. They are tiny chemical compounds and were discovered in 1911 by Casimir Funk, a Polish scientist.

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This edited article about nature’s electricity originally appeared in Look and Learn issue number 682 published on 8 February 1975.

The electric ray (centre left) among other strange fish

For millions of years before man invented the electric battery and the dynamo, animals and plants had been generating electric currents. Even your body is a miniature power station.

Indeed, some living creatures are very powerful generators of electric current. Like the electric eel for example.

The electric eel lives in the muddy waters of the Orinoco and Amazon rivers of South America. Specimens are sometimes seen in zoos.

Although it is like an eel in appearance, the electric eel is quite different in its anatomy and belongs to a group of fish called gymnotids.

It is about seven feet long with a brown and orange body and a very blunt head. Only about one-eighth of its length is head and body. The rest consists of the tail, which contains the eel’s “battery” of electric cells.

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This edited article about the Great Barrier Reef originally appeared in Look and Learn issue number 669 published on 9 November 1974.

Visiting the Great Barrier Reef

Coral Islands and the beautiful coral reefs surrounding them are made up of the dead skeletons of animals which are related to sea anemones. A single coral is called a polyp and each one contains a hard skeleton made up of carbonate of lime. When the living polyps die, the hard skeletons are left and these form reefs on which other corals in turn live and die to build up the reef layer by layer.

There are three main kinds of reefs; fringing reefs, barrier reefs and atolls. Fringing reefs are found around islands and along the shores of continents, while barrier reefs lie much farther from the mainland. Atolls are ring shaped or horseshoe-shaped reefs in the open ocean.

Off the east coast of Queensland in Australia is the greatest mass of coral in the world. This is the Great Barrier Reef which stretches for 1,200 miles. It is a number of reefs together, and the sea around the outer reef is very deep. Towards the north, the Reef is almost within sight of land, but in the south where it breaks up into clumps of coral scattered at various distances, the reef is as much as 150 miles away from the shore.

The coral is usually either brown or yellow but some of them are vivid blue or orange. At low tide the coral can take on very strange shapes and look rather like mushrooms.

There is a very active animal life found among the Reef. Great numbers of sea birds inhabit the area, and in the water live giant clams, sea urchins with poisonous spines, small, brightly coloured fish, sponges, oysters, and sea cucumbers.

This edited article about fish originally appeared in Look and Learn issue number 659 published on 31 August 1974.

The Cleaner Wrasse (bottom) removes sponges, fish-lice and dead skin from larger fish and even cleans the shark’s teeth

It is only since skin-diving became popular that the extraordinary behaviour of ‘Barber’ fish has become known. It was noticed that certain small fish pecked and nibbled at the bodies of larger fish, which apparently welcomed this attention. Indeed, there were often other fish queuing up awaiting their turn like customers at a barber’s shop. It was then noticed that these “barbers” were feeding on fish lice fungi and dead skin and were also cleaning the small wounds, to the great benefit of their “customers.” A small wrasse had been seen to enter the mouth of a great Barracuda, cleaning its long sharp teeth and even disappearing down its gullet to continue its work before re-emerging safely. One American observer counted 300 fish which were attended to in the space of six hours by a single “cleaner” fish. Their clients give every assistance to the cleaners and some even change colour to show up infected areas or sore spots.

A regular customer of the ‘barber’ fish is the “Surgeon” fish, so called because it has spines like sharp razor blades on each side of the tail.

This edited article about fish originally appeared in Look and Learn issue number 658 published on 24 August 1974.

Greater Pipe Fish (middle)

The pipe fish is curious eel-like fish which has two very unusual behaviour patterns. Firstly, it has a habit of swimming almost upright in the water so that a number together look like strands of seaweed or clumps of reed .

Secondly, the female fish lays her eggs into a brood-pouch on the male who then has the sole responsibility for incubating the eggs. After about two weeks the pouch opens and the tiny pipe fish are released one by one.

This edited article about fish originally appeared in Look and Learn issue number 657 published on 17 August 1974.

The Kissing Gourami is a small, silvery fish, often kept in aquariums. A pair in an aquarium will face each other and after a slight swaying motion, will clamp their lips together in an exaggerated “kiss.”

Some experts believe that this is more likely an act of aggression, rather than a preliminary to courtship.

This edited article about fish originally appeared in Look and Learn issue number 655 published on 3 August 1974.

The upside-down Catfish (top row, second from left)

Catfish get their name from the long “feelers” or barbels which are supposed to resemble the whiskers of a cat.

One of the biggest, known as the Wels, is a native of Eastern Europe and grows up to 10 feet long.

Perhaps the most extraordinary is the “upside-down” catfish. It has the remarkable habit of turning completely upside-down and swimming along like this for some time before reverting to a normal swimming position.

Another curious kind is the “glass” catfish which is almost completely transparent when young and even when it becomes adult, the only visible colouring is around the head.

In a fish-tank, it looks exactly like a swimming skeleton.

This edited article about fish originally appeared in Look and Learn issue number 654 published on 27 July 1974.

Climbing perch by Susan Cartwright

The Climbing Perch is one of the few fishes which have developed a rudimentary kind of lung so that it can travel overland in search of new water habitats. It does this by using its spiky fins, gill covers, and tail to propel itself out of the water, climbing over any obstacle in the way and travelling at about 200 yards an hour.