动物是多细胞真核生命体中的一大类群，称之为动物界。动物身体的基本形态会在它们发育时变得固定，通常是早在其胚胎发育时，但也有些会在其稍后的生命中有个变态的过程。大多数动物是能动的，它们能自发且独立地移动。绝大多数动物是消费者，它们依靠其他生命体（如植物）作为其食粮。但也有少部分动物属于清者——以已经死亡的生物体（有机质）作为食粮（例如蚯蚓）。
动物有着各种行为，这些行为可以看作是动物对刺激的反应。行为学是研究动物行为的科学。比较有名的行为理论是康纳德·洛伦茨提出的本能理论。
大多数已知出现在化石中的动物们多是在5亿4千万年前的寒武纪大爆发时的海洋物种。寒武纪大爆发对于进化来说是一个极大的挑战。
海洋就是地球上最大的生态群系，地球上最初的生命便是在此孕育。
Animals are a large group of eukaryotic cells, known as the Animal Kingdom. The basic morphology of the animal body becomes fixed at the time of their development, usually as early as the embryo develops, but some will have a metamorphosis in their later life. Most animals are active, and they can move spontaneously and independently. The vast majority of animals are consumers, and they rely on other living bodies (such as plants) as their food. But there are also few animals that belong to the Qing-people who have died of the organism (organic matter) as food (for example earthworms).
Animals have a variety of behaviors, which can be viewed as an animal's response to stimuli. Behavioral science is the study of animal behavior. The famous behavioral theory is Connald Lorentz's instinct theory.
Most of the animals that are known to appear in fossils are marine species at the time of the Cambrian outbreak of 540 million years ago. The Cambrian outbreak is a great challenge for evolution.
The ocean is the largest ecosystem on Earth, and the first life on Earth is conceived here.