1. Eukaryotic Cells: Animals are made up of eukaryotic cells, meaning their cells have a nucleus and other membrane-bound organelles.
2. Heterotrophic: Animals cannot produce their own food, so they must consume other organisms (plants, animals, fungi, bacteria) to obtain energy.
3. Multicellular: Animals are made up of many cells that are specialized to perform different functions.
4. Movement: Animals can move at some point in their life cycle, whether through locomotion, muscle contractions, or cilia/flagella.
5. Reproduction: Animals reproduce sexually, with the exception of some species that reproduce asexually. This typically involves the fusion of sperm and egg cells to form a zygote.
6. Growth and Development: Animals grow and develop after fertilization, undergoing a process of cell division and differentiation.
7. Sensory Systems: Animals have developed various sensory systems to perceive their environment and respond to stimuli. These include sight, touch, smell, taste, and hearing.
8. Nervous System: Most animals have a nervous system that coordinates their activities, allowing for rapid responses to stimuli.
9. Tissues: Animals have specialized tissues, such as muscle, nervous, and connective tissues, which work together to form organs and organ systems.
10. Collagen: Animals possess collagen, a structural protein that provides support and flexibility to their tissues.
11. Homeostasis: Animals maintain a stable internal environment through processes like temperature regulation, pH balance, and fluid balance.
These characteristics define the animal kingdom and distinguish it from other kingdoms like plants, fungi, and bacteria.
