Overview
This lecture covers the classification and unique characteristics of the Animal Kingdom, including major groups, organizational levels, body symmetry, and organ system patterns.
Characteristics of the Animal Kingdom
- Animals are eukaryotic, multicellular organisms belonging to Kingdom Animalia.
- They lack rigid cell walls, unlike algae, plants, and fungi.
- Animals obtain energy as heterotrophs by consuming plants or other animals.
- Most animals are motile at some life stage.
Major Groups in the Animal Kingdom
- Protozoa: Unicellular, eukaryotic organisms showing animal-like motility and predation.
- Bryozoans: Also called moss animals; mainly aquatic, colonial filter feeders with zooids.
- Vertebrates: Animals with backbones, including fish, amphibians, reptiles, mammals, and birds.
Levels of Organization in Animals
- Cellular Level: Animals consist of loosely associated cells without true tissues.
- Tissue Level: Cells grouped to perform specific functions, forming tissues.
- Organ Level: Tissues form organs specialized for particular functions (e.g., Platyhelminthes).
- Organ System Level: Organs combined into systems with distinct physiological tasks.
Organ System Patterns
- Circulatory System:
- Open type: Blood pumped into open spaces (e.g., Mollusca, Arthropods).
- Closed type: Blood flows through vessels (e.g., Annelids, Vertebrates).
- Digestive System:
- Complete: Separate mouth and anus for digestion (e.g., Chordates, Arthropods).
- Incomplete: Single opening for both ingestion and excretion (e.g., Platyhelminthes).
Types of Body Symmetry
- Bilateral Symmetry: Body can be divided into identical left and right halves.
- Radial Symmetry: Body arranged around a central axis (e.g., Coelenterates, Echinoderms).
- Asymmetrical: No symmetry; body cannot be divided evenly (e.g., Sponges).
Key Terms & Definitions
- Eukaryotic — Cells with a nucleus and organelles.
- Heterotroph — Organism obtaining food by consuming others.
- Motile — Capable of movement.
- Zooid — Individual animal in a bryozoan colony.
- Scutes — Bony external plates in reptiles.
- Symmetry — Balanced distribution of duplicate body parts.
Action Items / Next Steps
- Review examples of each animal group and level of organization.
- Learn more on Lower Invertebrates and Kingdom Plantae, Animalia, Viruses as suggested.