From the frozen poles to the sunless depths of ocean, from highest mountains to arid deserts, every region of our planet has been colonized by animals. Animals live in interactive partnerships with other species and with their physical environments.
Without animals, human could not survive.
Modern science is showing us how all living things are interconnected in complex ecosystem. By learning more about animals, we will be better able to conserve the natural world and to protect the earth’s wildlife for future generation.
The family of Animals looks at five groups of animals:
Mammals are the smallest group, but the mammals include the largest animal, the blue whale. The earth is rich in mammals. Mammals probably began to dominate the earth about 65 million years ago.
Human culture shifted from nomadic hunter-gatherers to a society based on agriculture. Human began to domesticate some mammals for work, meat, milk and for useful products such as wool and leather. These domestic animals included dogs, sheep, pigs, cows, goats and horses. There are 5,416 known mammal species.
Most aquatic mammals have thick layers of body fat instead of hair which in most land mammals serves to conserve heat. Seals, dolphins, bats and chimpanzees all have upper limbs with similar bones, but seals have flippers, dolphins have time, bats have wings and chimpanzees have arms.
Birds never cease to amaze us. Avian abilities are varied, including diving, swimming and complex nest building skills, but their ability to fly has long been envied by humans. Equally astonishing is the distance some bird fly. It has been estimated that more than 200 million birds migrate each year all over the planet.
Many birds fly thousands of miles, crossing desert and oceans to reach their breeding and feeding grounds. Much of bird behaviour, such as the ability of migrants to find their way across continents and back continues to be a mystery.
It is believed that there are approximately 9,700 birds species in the world. This makes birds the second largest vertebrate group of animals after fish.
Reptiles were the first vertebrate animals to be independent of water. Reptile rely on external heat to regulate their body temperature, many reptiles spends hours in the sun warming themselves by infraded radiation.
Humans have long feared and respected reptiles. Snakes, crocodiles and mythical dragons are found in legends of people throughout the world. These animals are often associated with magic.
There are about 8,200 species of reptiles. Many reptile species have impressive abilities: they can scale walls, burrow, swim, climb and even run warming themselves by infrared radiation.
4. Fish and Amphibians
Fish and amphibians were among the first vertebrates, creatures with internal skeletons and each species has evolved to help it survive in a specific habitat.
Fish are uniquely adapted to the watery world, with gills for breating and fins for swimming. They can live in oceans, lakes and freshwater rivers and streams.
Some of the world’s most exotic and brilliantly coloured animals are the fish of the warm tropical oceans, wild strange and little known fish in habits the cold dark Ocean deeps.
The most ancient forms of animal life on the earth are the invertebrates. They are also by far the most numerous. With more than 1.5 minion known species, it is estimated that 97% of all animal species are invertebrates.
Invertebrates exists in a variety of habitats and forms. Some are soft bodied animals, such as worms or jellyfish, while others such as insects and crustaceans have a hard external skeleton for protection. This fascinating group of creatures offers amazing examples of adaptation and habits.
Mosquitoes can pierce the skin of mammals and feed on their blood. No human athlete can match the jumping progress of the prowess of the tiny wingless flea. They play a vital role in food chain and ecosystem. So, they are very important to other species.