Animals Making a Home in Your Home
Animals are multicellular, meaning they are made up of multiple cell layers. Each animal has an exoskeleton (the skeleton), a digestive system (the gastrointestinal tract), a nervous system (the central nervous system), and reproductive organs (the reproductive organs). With a few exceptions, all animals can breathe oxygen, consume food, can move, and reproduce. They cannot be considered to be inorganic or living matter.
The classifications of animals can be broadly categorized into three domains: land animals (plant and animal) amphibians (water animals) and reptiles (land animals with a protective membrane). All belong to the Kingdom Protista. Insects are a class of multicellular organisms, a member of the Kingdom Insecta. All insectivores eat either meat or plant matter, but some are omnivores, which feed on both meat and plants. Virtually all insects have wings, although the flightless dragonfly is the only exception.
The order Animalia includes all the major animals and most plants. The Class Kingdom Animalia includes reptiles such as snakes and lizards, and mollusks such as clams and oysters. The Class Phylum Animalia includes fishes, amphibians, unnamiated bony fish and ungulates such as felines and primates. The Class Eutheria includes birds, mammals, reptiles, and insects. In this last classification, some new classifications such as placental mammals, which are not part of a previously existing class, have recently been discovered.
Plants and animals share many common traits, although their physiology and behavior are quite different from one another. Some animals secrete saliva, which protects their skin, hairs, and other body parts from the elements. Many insects secrete chemical compounds that serve as toxins, while others are incapable of so much self-protection. Most animals can swim, although it is not clear whether all vertebrates can swim, as dinosaurs are the only known aquatic animals in the vertebrate kingdom.
Insects are among the least studied animals in science and medicine. Few studies have been done on insects, but in one species of Asian insect, the Japanese Anemone shrimp, the females are the only creatures capable of flying. Insects belong to the Kingdom Animalia, the class of animals having no central nervous system, and are thus incapable of moving around in any way.
Birds, amphibians, ungulates, and mammals are classified into three main categories, including reptiles, mammals, and birds. All these animal groups are made up of microscopic creatures with an animal’s body separated into two parts: the exoskeleton, which are the skeleton and are underlying internal parts of the animal; and the tail, which are the tail. Insects make up the class Animalia, of which insects are one of the major groups of living organisms. The three main categories of animal life are: animals, chordata, and Protista.