Category Zoology

Amphibians can be red, blue, yellow, brown, or green and they come with spots, stripes, and many different types of markings. Some are darker on top with a completely different colour and pattern underneath. An amphibian’s colour may vary with humidity too, becoming pale when warm and dry, and dark when cold and damp.

There are several reasons why amphibians come in different colours. A bright colour is used to tell other animals whether a particular animal is poisonous or not. Tropical colours like reds, oranges and blues are so bright that they can be seen from afar. These colours signal predators that the animal is poisonous, and shouldn’t be eaten. On the other hand, some amphibians have bright colours to scare their enemies away. Many can change their colouring to mimic their surroundings, so that their enemies can’t see them. 

Amphibians live on both land and water, and so, their respiratory system must allow them to take in oxygen not only from the air, but also from water. Thus, they have a very complex respiratory system.

            When amphibians stay in the water, they breathe through their skin, but once they come on land, they breathe with their lungs, and through the membranes in their mouth. Even when the lungs are used, amphibians obtain oxygen through their skin- and for this to be possible, the skin must remain moist at all times.

            When an amphibian is in the larval stage, it uses gills for breathing. These gills later develop into lungs as the amphibian undergoes the changes that make it an adult. Some salamanders have neither gills nor lungs, but breathe through their mouths and skins.

            To sum up, amphibians can get oxygen into their bodies in three different ways. The first way is by using lungs, which are similar to ours. The second way is through their skin, and the last way, is by using gills. Did you know that amphibians don’t breathe constantly like humans do? Instead, they just breathe now and then, when their body needs more oxygen.

 For amphibians, water is essential for survival. To begin with, water keeps their skin moist, and they get the oxygen they need from the water that they absorb through their skin. Water is also vital for their reproduction. This is because the eggs of amphibians do not have a hard shell so they need water to keep them from drying out, and to protect them from the rays of the sun. Some species of amphibians are aquatic, and spend all their lives in water. Others spend the beginning of their lives in water as larvae, and later undergo a change called metamorphosis, and move on to land.

            Since, water is so important to them, amphibians like frogs seek out damp shady places to live in. Others try to prevent water loss by burrowing underground. In spite of being so dependent on water, amphibians rarely drink it! Isn’t that strange?

Jean Baptiste Lamarck believed that all bodies had ‘subtle fluids’. These were weightless fluids pervading all space and bodies. Two good examples of eighteenth – century subtle fluids were electricity and heat. Lamarck believed that subtle fluids were responsible for both movement and change. For example, Lamarck pointed out that snails have poor vision because the feelers on their heads acted as their eyes. According to him, the ancestors of snails did not have feelers. They groped about with their heads to find their way around. This groping sent subtle fluids to the front of the head, and the constant presences of moving subtle fluids eventually brought about the development of feelers, and these feelers were passed from generation to generatio 

Butterfly Evidence

         Lamarck supported his theory of evolution with the example of butterflies. According to him, you find different species of butterflies in different places because butterflies in one place acquire certain characteristics to survive in their environment, and pass on these characteristics to the next generation.

Lost Worlds

        The duck billed platypus of Australia is a strange looking bird that was discovered only in 1799. This made several people believe that there might be many other weird animals alive in some remote corner of our planet and that animals that were thought to be extinct might still exist in some unknown place.

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The Tasmanian tiger is one of the most fabled animals in the world. European settlers in Tasmanian were puzzled by it, feared it, and killed it when they could. After only a century of white settlement, the animal had been pushed to the brink of extinction. The Tasmanian tiger look like a large, long dog, with stripes, a heavy stiff tail, and a big head resembling that of a wolf. That is why it is sometimes called the Tasmanian wolf. It was shy and secretive, and always avoided contact with humans. It was a meat-eater. When the European began settling in Tasmania, the animal started killing the sheep and poultry raised by the settlers.As a result, Tasmanian tigers were hunted down relentlessly, and rewards were given to those who killed them.Another major factor that contributed to the Tasmanian tiger’s decline is the dingo, or wild dog population. These wild dogs hunted in packs, unlike Tasmanian tigers which hunted in small numbers or alone. Dingoes competed with these Tasmanian tigers for food and shelter. Climate changes and deforestation are also believed to have been contributing factors to their extinction. By 1936, the last captive Tasmanian tiger has died. 

A Chance for Rebirth

Although the Tasmanian tiger has been officially declared to be extinct, there have been unconfirmed reports of it being sighted. However, there is no hard evidence that the animal still exists. Efforts are being made to clone a specimen that has been preserved in alcohol. A team of Australian scientists has succeeded in replicating the DNA of the extinct Tasmanian tiger, and plan on reviving the species soon.

In the year 1507 AD, Portuguese sailors landing on the shores of the island of Mauritius discovered a strange looking bird. It was large and stubby, and could not fly. It had a hooked black beak, short yellow legs, grey-blue plumage, and tuft of pale coloured feathers for its tail. Since this bird had never seen humans before, it was very friendly and trusting. In fact, the sailors mistook its gentle nature for stupidity, and called it ‘dodo’, which meant simpleton in Portuguese.The dodo was an easy source of fresh meat for the Portuguese – and later, the Dutch who came to the island in 1598- because it could be easily captured due to its friendliness. Dodos were killed in large numbers by the new inhabitants of the island. Those that survived Man had to face new enemies like dogs and pigs that were introduced by these inhabitants. The dodo had no natural enemies on the island, but these new animals, together with Man, hastened its extinction. By the year 1681, the last dodo had died, and today, the term ‘as dead as a dodo’, means something that has disappeared entirely from the face of the Earth.

Dodo Tree

The extinction of the dodo almost led to the extinction of yet another species, a certain type of tree in Mauritius, which was known as the dodo tree. The seeds of this tree could only germinate after passing through the digestive tract of the dodo. When the dodo became extinct, no new trees grew on the island. However, the tree was saved from extinction when botanists fed its seeds to turkeys. The seeds passed through the turkey’s digestive system, and were propagated in the same way as when dodos were alive.