The Kingdom Animalia, also known as the animal kingdom, includes all multicellular, heterotrophic organisms without cell walls. Some of the key characteristics of this kingdom include:

1. Heterotrophic: Animals are heterotrophic, meaning they obtain their food by ingesting other organisms.
2. Multicellular: Animals are multicellular, with specialized tissues and organs that perform different functions.
3. Mobility: Most animals are capable of movement, and some have adaptations, such as wings, fins, or legs, that allow them to move effectively.
4. Sensory organs: Animals have sensory organs, such as eyes, ears, and noses, that allow them to perceive and respond to their environment.
5. Diversity: The Kingdom Animalia is incredibly diverse, with a wide range of species including sponges, jellyfish, worms, insects, fish, reptiles, birds, and mammals.

Animals play a crucial role in the Earth’s ecosystem, as they are predators, prey, decomposers, and pollinators. They also have significant cultural and economic value, as they serve as food, pets, and symbols in human societies.