* Body Structure: Animals are grouped based on their anatomical features like:
* Symmetry: Radial (like starfish), Bilateral (like humans), or Asymmetry (like sponges)
* Body Cavity: Presence or absence of a coelom (a fluid-filled space)
* Tissue Organization: Differentiation into specialized tissues and organs
* Skeletal System: Presence or absence of an internal or external skeleton
* Digestive System: Type of mouth, digestive tract, and excretion methods
* Other Characteristics: Besides body structure, taxonomy considers:
* Evolutionary Relationships: How animals are related through common ancestry
* Embryonic Development: Early stages of development and similarities
* Genetic Data: Comparing DNA and RNA to understand relationships
* Ecology: Habitats, diets, and behaviors
Example:
* Vertebrates are a large group of animals that share a common ancestor and have a backbone (vertebrate column).
* Mammals are a group within vertebrates that have fur or hair, produce milk to feed their young, and are generally warm-blooded.
Therefore, body structure plays a crucial role in animal classification, but it's not the only factor. Taxonomy combines various characteristics to create a comprehensive system for understanding the diversity of life on Earth.