Most fish breathe by extracting oxygen from 'water, by means of their gills. Gills are delicate filaments of tissue through which blood passes. As water flows over the gills, oxygen diffuses into the blood.

However, some fish have an additional method of ob...

The little-known hoatzin which lives in the mangrove swamps of Venezuela. Young hoatzins have two small claws on their wings, and they use these to help grip the branches, as they clamber about the trees.

They are poor fliers even when adu...

Surprisingly, only one species of cat lives in a well-ordered and organized group, and that species is the lion. Groups of lions are called prides, and they usually consist of one or two males together with several lionesses and their cubs.

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The hermit crab Instead of scuttling about proteoed by its own tough shell like other crabs, it has a soft body which it protects inside the empty shells of whelks and° other molluscs. The hermit crab finds a suitable shell and eases its body inside. Then, with ...

You probably know that tigers live in jungles, and you may know that some come from India, but do you know that there are eightdistinct races of tiger scattered throughout Asia? The tiger ranges from Iran to Turkestan, Mongolia, Siberia and Korea. It is also found thro...

Antelopes, cows, goats, and sheep have horns. Horns are composed of a bony central core attached to the skull and covered in a horny sheath: The horny sheath is `grown' by a layer of tissue covering the bony core. Horns cojitinue to/grow throu...

In terms of sheer bulk, the blue whale must take the prize. Every time it takes a mouthful of shrimp-like krill, it swallows literally thousands upon thousands of individuals. When full, the blue whale's stomach can hold as much as 2.5 tonnes...

It is very difllcult to evaluate intelligence in terms of animals such as birds. In the wild, there are birds that use small sticks in their beaks to poke insects from the bark of trees and, in urban areas of some countries, others which peck the tops from...

The dodo, a large clumsy bird which could not fly, used to live on the island of Mauritius near Africa. But European settlers changed the dodo's habitat and took away its supply of food. By 1681, there were no living dodos. It was extinct. Many other kinds of a...

In remote parts of the world, where animals might easily get lost among craggy mountains or in deep forests, bells are tied to them.

In Switzerland, beautiful carved and painted bells are hung around the necks of cows as they graze. Some herders be...