Organism size

Organism size refers to how large or small a living creature is, usually measured by its length, height, or biomass. It varies widely across species—from tiny microorganisms like bacteria to massive animals like whales. Size affects various aspects of an organism's biology, including how it moves, finds food, reproduces, and interacts with its environment. Factors such as genetics, environmental resources, and climate influence size; for example, abundant resources often support larger body sizes. Understanding organism size helps scientists learn about ecological roles, evolutionary adaptations, and how different species survive and thrive in their habitats.