Animalia Chordata Placozoan Artropod Characteristics Essentially, animals are many-celled heterotrophic organisms. Plants and algae characteristically manufacture their food from inorganic substances (usually by photosynthesis). Animals must secure food already organized into organic substances. Animals (as well as plants) provide carbon dioxide through respiration and the decomposition of their dead bodies. In addition, most animals have specialized means of locomotion, generally involving muscle cells, and possess nervous systems and sense organs–all adaptations for securing food. In most forms there is a distinct canal or digestive system. Animal cells do not have cell walls. Almost all animals, unlike most plants, possess a limited amount of growth; that is, the adults of a given species are nearly identical in their characteristic form and are similar in maximum size. Social roles of cows • Cows give humans beef, milk, leather and cheese. • Cows affect the environment by eating to much vegetation, polluting the water, and they cause more erosion. • Cows are used for working and pulling things. Bibliography • http://education.yahoo.com/reference/ency clopedia/entry/animal • www.teachnet.ie • www.awsomeflorida.com • www.marinebio.org Presented by • Trinity And Kailey Yay!