Animal Kingdom - Chapter 4

4.1 Basis of Classification

• Classification of animals is essential due to the diversity and helps in systematic categorization.
• Fundamental Features for Classification:
  • Arrangement of cells
  • Body symmetry
  • Nature of coelom
  • Patterns of digestive, circulatory, or reproductive systems

4.1.1 Levels of Organisation

• Cellular Level: Seen in sponges with loose cell aggregates.
• Tissue Level: Coelenterates have tissues where cells work together.
• Organ Level: Platyhelminthes and higher phyla where tissues form organs.
• Organ System Level: Annelids, arthropods, molluscs etc. have functional systems for physiological processes.
  • Digestive System: Can be incomplete (single opening) or complete (mouth and anus).
  • Circulatory System: Open type (blood bathes tissues directly) or closed type (blood circulates in vessels).

4.1.2 Symmetry

• Asymmetrical: Sponges
• Radial Symmetry: Coelenterates, ctenophores, echinoderms
• Bilateral Symmetry: Annelids, arthropods

4.1.3 Diploblastic and Triploblastic Organisation

• Diploblastic: Two embryonic layers (ectoderm and endoderm) with mesoglea in between. Example: Coelenterates
• Triploblastic: Three layers (ectoderm, mesoderm, endoderm). Example: Platyhelminthes to Chordates

4.1.4 Coelom

• Coelomates: Have a true coelom. Example: Annelids
• Pseudocoelomates: Coelom not lined by mesoderm. Example: Aschelminthes
• Acoelomates: Lack a coelom. Example: Platyhelminthes

4.1.5 Segmentation

• Metamerism: Serial repetition of organs. Example: Earthworm

4.1.6 Notochord

• Rod-like structure present in chordates.

4.2 Classification of Animals

• Classification based on fundamental features.

4.2.1 Phylum Porifera

• Commonly called sponges; marine and asymmetrical.
• Have a canal system for water transport.
• Reproduce sexually and asexually.

4.2.2 Phylum Coelenterata (Cnidaria)

• Aquatic, radially symmetrical; exhibit tissue level organisation.
• Have cnidoblasts for defense and prey capture.

4.2.3 Phylum Ctenophora

• Known as sea walnuts; marine with comb plates for locomotion.

4.2.4 Phylum Platyhelminthes

• Flatworms; mostly parasitic.
• Bilaterally symmetrical, acoelomate.

4.2.5 Phylum Aschelminthes

• Roundworms; pseudocoelomate.
• Separate sexes and complete alimentary canal.

4.2.6 Phylum Annelida

• Segmented worms; true coelom.
• Closed circulatory system.

4.2.7 Phylum Arthropoda

• Largest phylum; jointed appendages and chitinous exoskeleton.

4.2.8 Phylum Mollusca

• Second largest; soft body with calcareous shell.

4.2.9 Phylum Echinodermata

• Marine; have water vascular system.

4.2.10 Phylum Hemichordata

• Previously a sub-phylum under Chordata.
• Worm-like marine animals.

4.2.11 Phylum Chordata

• Presence of notochord, dorsal nerve cord, and gill slits.
• Subphyla:
  • Urochordata
  • Cephalochordata
  • Vertebrata

Vertebrata Classes

• Cyclostomata: Jawless, ectoparasites.
• Chondrichthyes: Cartilaginous fishes.
• Osteichthyes: Bony fishes.
• Amphibia: Live in water and on land.
• Reptilia: Terrestrial with dry skin.
• Aves: Birds with feathers.
• Mammalia: Milk-producing glands, hair on skin.

Summary

• Classification based on fundamental features like levels of organization, symmetry, and coelom.
• Detailed understanding of each phylum's distinctive features.

Exercises

1. Why is classification based on fundamental features important?
2. Steps to classify a specimen.
3. Importance of coelom in classification.
4. Intracellular vs extracellular digestion.
5. Direct vs indirect development.
6. Features of parasitic platyhelminthes.
7. Why are arthropods the largest group?
8. Identify group with water vascular system.
9. Justify that all vertebrates are chordates.
10. Importance of air bladder in Pisces.
11. Flight adaptations in birds.
12. Comparison of egg production in oviparous and viviparous animals.
13. First phylum with segmentation.
14. Match distinctive features with phyla.
15. List parasitic animals on humans.