The word “animals” is used to refer to a number of different classes of animals, including Plants, amphibians, reptiles, mammals, insects, crustaceans, mollusks, protozoans, sharks, fish, birds, etc. Animals are classified into several types or classifications depending on the way they reproduce (or lack reproduce), their physiology, behavior, diet, geographic location, and habitat. Most animals are multicellular, living organisms in the Kingdom Animalia. With the exception of jellyfish, all other animals are found in a aquatic or semi-aquatic environment.
Animals reproduce differently than plants and even in animals. For instance, some animals secrete a particular chemical scent as a mating call; other animals produce a sound to attract mates; and still others alarm their offspring by emitting certain hormones. Other animals may run or walk faster than the speed of sound, depending on the direction of their flight or movement. They also have senses other than sight and smell, including touch, taste, and hearing.
Animals breathe air, eat food, and grow; all without a digestive system. They do not have skin or fur; they have no nervous system and are not endowed with the self-awareness of higher animals. They are thus far superior to human beings in almost every respect except that they are unable to speak. A wide variety of animals exist in nature, including mammals, birds, reptiles, insects, millipedes, arthropods, fishes, amphibians, crustaceans, and mollusks. In fact, there are more animals in this world than we can count.