Fish are cold blooded (usually) animals that live in the water. They are covered with scales and are equipped with two sets of paired fins. Fish exchange gases through their gills and most lay their eggs in water.
Amphibians are cold blooded animals that morph from water breathing animals into air breathing animals, although some continue to breath water into adulthood. Some examples are frogs, toads, and salamanders. Amphibians typically have four limbs and they lay their eggs in water.
Reptiles are cold blooded animals, that lay eggs, and breath through lungs. Some examples of reptiles are turtles, alligators, and crocodiles. Reptiles are covered with a horny epidermis which provides them with protection from prey.
Mammals are air breathing animals that typically give birth to live young. Mammals are divided into three groups depending on how they were born. They may be classified as monotremes (egg layers), marsupials (pouched), and placentals (live births). Some examples of mammals are the bat, dog, and kangaroo. The mammal group is very diversified. Some swim (blue whale), some hop (kangaroo), and some fly (bat).
Fishes are vertebrate animals that live in water. Various kind of differ widely in shape colour and size. Thus different kind of fishes number more than all other kind of land and water vertebrates put together.
Some fish look like lumpy rocks, and others like wriggly worms. Some fish are nearly as flat as pancakes, and others can blow themselves up like balloons. Many have many different colours that are as bright as those of the most brightly coloured birds.
All fish have two main features in common. (1) They have a backbone, and so they are vertebrates. (2) They breathe mainly by means of gills. Nearly all fish are also cold-blooded animals.In addition, almost all fish have fins, which they use for swimming. All other water animals differ from fish in at least one of these ways.
Amphibians are a class of animals within the vertebrates. There are about 3,200 kinds of amphibians, which include species such as frogs, toads, salamanders, and caecilians.
Amphibians - with a few exceptions - live part of their life in water and part on land. They hatch from eggs laid in water or moist ground, and begin life as water-dwelling larvae. Over a period the larvae change into adults which look very different from the larvae. Most adults spend their lives on land. while some continue to live in water But almost all return to water to for mating.
Amphibians are divided into three groups: (1) frogs and toads; (2) salamanders; and (3) caecilians.
Reptiles are cold blooded vertebrate animals with dry, scaly skin, who breathe by means of lungs There are about 6,500 species of reptiles, Reptiles include alligators, crocodiles, lizards, snakes, turtles, and the tuatara.
Many reptiles live a long time, and some turtles have lived in captivity for more than 100 years. Reptiles live on every continent except Antarctica and in all the oceans except those of the polar regions.
Birds are animals with feathers. There are no other animals with feathers. Bird are generally able to fly and achieve great speed. The fastest birds can fly at speed exceeding 160 kilometers per hour. However, not all birds can fly.
There are about 9,300 species of birds. The smallest bird is the bee hummingbird, which is about 5 centimetres long. The largest bird is the ostrich, which may grow to about 2.5 metres height.
Mammals are vertebrates that feeds its young on the mother's milk. There are about 4,500 kinds of mammals including human beings.
Mammals live almost everywhere on land as well as in water. Blue whale, the largest animal that ever lived, is a mammal, measuring more than 30 metres long and weighing more than 150 tons. The smallest mammal is the Kitti's hog-nosed bat of Thailand which weighs only about 2 grams.
Mammals differ from all or most other animals in five major ways.
- Mammals feed their babies on the mother's milk.
- Most mammals give their young more protection and training than other animals do.
- Only mammals have hair. All mammals have hair at some time in their life.
- Mammals are warm-blooded
- Mammals have a larger, more well-developed brain than other animals do.