A CLOSER LOOK AT THE ANIMAL KINGDOM creature on Earth It can grow to be more than 100 feet 30 meters long and weight 300 000 pounds 136 000 kilograms Scientists also study how animals adapt to their environments While some animals are solitary others are more social Bees live in hives Wolves live in packs Some build homes Groundhogs live in complex under ground burrows with connecting tunnels Other animals have adapted themselves to live with humans such as our closest com panions dogs No doubt about it animals large and small including us adapt themselves to survive in many different ways This volume will help you to understand and identify the animals that live around you whether you're in a bustling city a quiet suburb or out in the country and those that popu late our planet Io
CHAPTER 1 THE VARIETY OF ANIMAL LIFE iving things are divided into three main groups called domains Single celled organisms called bacteria and archaea each constitute their own domain All other organisms make up at third domain Eukarya which includes not only single celled algae and protozoa but also animals and other multicellular organisms Animals form the largest group within the Eukarya They range from very simple invertebrates such as sponges to highly complex mam mals such as whales monkeys and humans Animals display some key differences that distinguish them from other living things For example what is the difference between an animal such as a horse and a plant such as grass A horse moves around in the pasture eating grass It trots toward you when you offer it a lump of sugar and reacts favorably when you stroke its head The grass however is rooted to one place It does not respond behaviorally to people or to the horse in any A horse eats grass in Oxfordshire England Tim Graham Photo Library Getty Images I2
