Animal Kingdom - NEET/11th Bio Notes
Basis of Classification
Animals are classified based on:
1. Level of organization - Cellular / Tissue / Organ / Organ system
2. Symmetry - Asymmetrical / Radial / Bilateral
3. Germ layers - Diploblastic (2) / Triploblastic (3)
4. Coelom - Acoelomate / Pseudocoelomate / Coelomate
5. Segmentation - Present (metameric) or absent
6. Notochord - Present in chordates, absent in non-chordates
Levels of Organization
- Cellular: Cells arranged loosely (e.g., Sponges)
- Tissue: Groups of cells for a specific function (e.g., Cnidarians)
- Organ system: Specialized organs (e.g., Annelida to Chordata)
Symmetry
- Asymmetrical: No symmetry (e.g., Sponges)
- Radial: Divided into equal halves in any plane (e.g., Cnidaria, Echinodermata)
- Bilateral: Divided into two equal halves in one plane (e.g., Platyhelminthes to Chordata)
Germ Layers
- Diploblastic: Two layers - ectoderm & endoderm (e.g., Cnidaria)
- Triploblastic: Three layers - ecto, meso & endoderm (e.g., Platyhelminthes onwards)
Coelom
- Acoelomate: No body cavity (e.g., Platyhelminthes)
- Pseudocoelomate: False coelom (e.g., Aschelminthes)
- Coelomate: True body cavity (e.g., Annelids to Chordates)
Basis of Classification
Animals are classified based on:
1. Level of organization - Cellular / Tissue / Organ / Organ system
2. Symmetry - Asymmetrical / Radial / Bilateral
3. Germ layers - Diploblastic (2) / Triploblastic (3)
4. Coelom - Acoelomate / Pseudocoelomate / Coelomate
5. Segmentation - Present (metameric) or absent
6. Notochord - Present in chordates, absent in non-chordates
Levels of Organization
- Cellular: Cells arranged loosely (e.g., Sponges)
- Tissue: Groups of cells for a specific function (e.g., Cnidarians)
- Organ system: Specialized organs (e.g., Annelida to Chordata)
Symmetry
- Asymmetrical: No symmetry (e.g., Sponges)
- Radial: Divided into equal halves in any plane (e.g., Cnidaria, Echinodermata)
- Bilateral: Divided into two equal halves in one plane (e.g., Platyhelminthes to Chordata)
Germ Layers
- Diploblastic: Two layers - ectoderm & endoderm (e.g., Cnidaria)
- Triploblastic: Three layers - ecto, meso & endoderm (e.g., Platyhelminthes onwards)
Coelom
- Acoelomate: No body cavity (e.g., Platyhelminthes)
- Pseudocoelomate: False coelom (e.g., Aschelminthes)
- Coelomate: True body cavity (e.g., Annelids to Chordates)
