1. Multicellularity: Animals are multicellular organisms, meaning their bodies are composed of multiple cells that work together to perform various life functions.
2. Heterotrophy: Animals are heterotrophic organisms, which means they obtain nutrients and energy by consuming other organisms or their byproducts.
3. Mobility: Most animals are mobile, capable of moving from one place to another at some point in their life cycle. Some may have limited mobility, while others are highly mobile.
4. Reproduction: Animals reproduce sexually or asexually, resulting in the production of offspring. Sexual reproduction involves the fusion of gametes, while asexual reproduction occurs without the involvement of gametes.
5. Growth and Development: Animals undergo growth and development throughout their life cycle. They may go through different stages, such as embryonic development, larval stage (in some animals), juvenile stage, and adulthood.
6. Response to Stimuli: Animals are capable of responding to external and internal stimuli. They can sense changes in their surroundings and react accordingly. For example, they might move away from danger or towards a source of food.
7. Specialization of Cells and Tissues: Animals have specialized cells and tissues that perform specific functions. This allows for efficient organization and coordination within their bodies.
8. Organization: Animals are organized into various levels of complexity, from individual cells to tissues, organs, organ systems, and whole organisms.
9. Adaptation and Evolution: Animals have the ability to adapt to changing environmental conditions through evolution. Over time, populations of animals can develop traits that enhance their survival and reproductive success in a particular environment.
10. Evolutionary History: Animals belong to the kingdom Animalia and share a common evolutionary ancestor. While they exhibit great diversity in forms and adaptations, they all have shared evolutionary traits that define them as animals.