Classification of the Animal Kingdom

Study Notes

Kingdom Animalia is divided into several groups based on characteristics and evolutionary relationships
The main classification categories are:
1. Domain: Eukarya (eukaryotic cells)
2. Kingdom: Animalia (multicellular, eukaryotic, heterotrophic)
3. Phylum (or Division in some classifications): 35-40 phyla, each representing a distinct body structure
4. Class: groups of related phyla
5. Order: groups of related classes
6. Family: groups of related orders
7. Genus: groups of related families
8. Species: the most specific classification unit

Multicellularity: composed of multiple cells
Eukaryotic cells: cells with true nuclei and membrane-bound organelles
Heterotrophy: obtain energy by consuming other organisms or organic matter
Mobility: ability to move, although some species have limited or no mobility
Response to stimuli: ability to respond to environmental stimuli
Growth and development: ability to grow and develop from embryos to mature individuals

Radial symmetry: body parts arranged around a central axis (e.g., starfish, sea urchins)
Bilateral symmetry: body parts arranged around a central axis with mirror-image symmetry (e.g., humans, insects)
Body cavities: fluid-filled spaces within the body (e.g., coelom, pseudocoelom)
Body layers: three primary layers: ectoderm, endoderm, and mesoderm

Invertebrates: animals without backbones (e.g., insects, mollusks, echinoderms)
Vertebrates: animals with backbones (e.g., fish, amphibians, reptiles, birds, mammals)
Water-dwelling animals: aquatic animals (e.g., fish, marine mammals)
Land-dwelling animals: terrestrial animals (e.g., insects, reptiles, mammals)
Flying animals: animals capable of flight (e.g., insects, birds, bats)

Kingdom Animalia is divided into groups based on characteristics and evolutionary relationships
The main classification categories are: Domain, Kingdom, Phylum, Class, Order, Family, Genus, and Species
Domain Eukarya is characterized by eukaryotic cells
Kingdom Animalia is characterized by being multicellular, eukaryotic, and heterotrophic

Multicellularity is a characteristic of animals, composed of multiple cells
Eukaryotic cells have true nuclei and membrane-bound organelles
Heterotrophy is the ability to obtain energy by consuming other organisms or organic matter
Mobility is the ability to move, although some species have limited or no mobility
Response to stimuli is the ability to respond to environmental stimuli
Growth and development is the ability to grow and develop from embryos to mature individuals

Radial symmetry is a body structure where parts are arranged around a central axis
Bilateral symmetry is a body structure where parts are arranged around a central axis with mirror-image symmetry
Body cavities are fluid-filled spaces within the body, such as coelom or pseudocoelom
Body layers are three primary layers: ectoderm, endoderm, and mesoderm

Invertebrates are animals without backbones, such as insects, mollusks, and echinoderms
Vertebrates are animals with backbones, such as fish, amphibians, reptiles, birds, and mammals
Water-dwelling animals, such as fish and marine mammals, live in aquatic environments
Land-dwelling animals, such as insects, reptiles, and mammals, live in terrestrial environments
Flying animals, such as insects, birds, and bats, are capable of flight