Animal Kingdom Lecture Notes

Introduction

• Instructor: Diksha Ma'am
• Topic: Animal Kingdom
• Importance: Crucial for NEET, questions mostly based on NCERT.
• Focus: Memorization ease, NCERT lines, up to class level in chordates.

Characteristics of Animals

• Multicellular: Composed of multiple cells.
• Heterotrophic Nutrition: Cannot produce own food; holozoic ingestion (eating through mouth).
• Movement & Sensory Organs: Can move, possess sensory organs and neurons (exceptions like sponges).
• Eukaryotes: Complex cell structure.
• Exceptions: Sponges lack neurons and sense organs.

Need for Classification

• Simplifies study of animals by grouping common characteristics.
• Example: Similar characteristics in cockroach and ant.
• Classification Basis:
  • Level of Organization
  • Symmetry
  • Germ Layers
  • Coelom
  • Segmentation
  • Notochord

Major Phylums in Brief

1. Porifera: Simplest, sponges.
2. Cnidaria: Also known as Coelenterata.
3. Ctenophora
4. Platyhelminthes: Flatworms.
5. Aschelminthes or Nematoda
6. Annelida: Segmented worms.
7. Arthropoda: Largest phylum, insects, crustaceans.
8. Mollusca
9. Echinodermata
10. Hemichordata
11. Chordata

Basis of Classification Explained

Level of Organization

1. Cellular Level: Loosely aggregated cells (e.g., Porifera).
2. Tissue Level: Cells working as tissues (e.g., Cnidaria, Ctenophora).
3. Organ Level: Tissues form organs (e.g., Platyhelminthes).
4. Organ System Level: Organs form systems (e.g., Aschelminthes to Chordates).

Symmetry

1. Asymmetrical: Cannot be divided into equal halves (e.g., Sponges).
2. Radial Symmetry: Multiple planes can divide into equal halves (e.g., Cnidaria).
3. Bilateral Symmetry: Single plane divides into equal halves (e.g., Platyhelminthes to Chordates).

Germ Layers

1. Diploblastic: Two layers - Ectoderm and Endoderm (e.g., Cnidaria).
2. Triploblastic: Three layers - Ectoderm, Mesoderm, Endoderm (e.g., Platyhelminthes to Chordates).

Coelom

1. Acoelomate: No body cavity (e.g., Platyhelminthes).
2. Pseudocoelomate: False body cavity (e.g., Nematoda).
3. Eucoelomate: True body cavity (e.g., Annelida to Chordates).

Segmentation

• True Segmentation (Metamerism): Both internal and external segmentation (e.g., Annelida, Arthropoda, Chordata).
• False Segmentation (Pseudometamerism): Only external segmentation (e.g., Tapeworm).

Notochord

• Present in Chordates: Divided into sub-phyla depending on presence throughout life or specific stages.
• Absent in Non-Chordates: Phylum from Porifera to Hemichordata.

Detailed Phylum Discussion

Phylum Porifera

• Example: Sponges
• Characteristics:
  • Marine, few freshwater (e.g., Spongilla).
  • Water transport system with Ostia and Osculum.
  • Skeleton: Spicules and Spongin fibers.
  • Reproduction: Asexual (fragmentation, budding) and Sexual (Hermaphrodite).

Phylum Cnidaria

• Example: Hydra, Jellyfish (Aurelia)
• Characteristics:
  • Aquatic, mostly marine.
  • Body Forms: Polyp and Medusa.
  • Special Cells: Cnidocytes/nematocysts for defense and prey capture.
  • Reproduction: Both Asexual and Sexual, Alternation of generations (Metagenesis in Obelia).

Phylum Ctenophora

• Example: Pleurobrachia, Ctenoplana
• Characteristics:
  • Exclusively marine.
  • Bioluminescence: Emit light.
  • Comb Plates: For locomotion.
  • Reproduction: Sexual, Hermaphrodite.

Phylum Platyhelminthes

• Example: Planaria, Tapeworm (Taenia), Liver fluke (Fasciola)
• Characteristics:
  • Dorsoventrally flattened body.
  • Parasitic adaptations: Hooks and suckers.
  • Excretion: Flame cells.

Phylum Aschelminthes (Nematoda)

• Example: Roundworm (Ascaris), Filarial worm (Wuchereria)
• Characteristics:
  • Cylindrical body.
  • Digestive System: Complete with muscular pharynx.
  • Excretion: Renette cells.

Phylum Annelida

• Example: Earthworm (Pheretima), Leeches (Hirudinaria)
• Characteristics:
  • Metamerically segmented body.
  • Excretion: Nephridia.
  • Respiration: Through skin (cutaneous), parapodia in marine forms.

Phylum Arthropoda

• Example: Insects (cockroach, ants), Crustaceans (crabs)
• Characteristics:
  • Largest phylum.
  • Body Segmentation: Head, thorax, abdomen.
  • Excretion: Malpighian tubules, Green glands in prawns.
  • Respiration: Gills, tracheal system.

Phylum Mollusca

• Example: Snails, Octopus
• Characteristics:
  • Soft body, often with a calcareous shell.
  • Body Divisions: Head, Visceral hump, Muscular foot.
  • Respiration and Excretion: By gills (Ctenidia).

Phylum Echinodermata

• Example: Starfish (Asterias), Sea urchin (Echinus)
• Characteristics:
  • Spiny skin.
  • Endoskeleton: Calcareous plates (ossicles).
  • Water Vascular System: For locomotion, respiration, and excretion.

Phylum Hemichordata

• Example: Balanoglossus (Tongue worm)
• Characteristics:
  • Marine, worm-like body.
  • Body Division: Proboscis, collar, trunk.
  • Excretion: Proboscis gland.

Chordata Subphyla

Subphylum Urochordata (Tunicata)

• Example: Ascidia
• Characteristics:
  • Marine.
  • Notochord: Present in larval tail.
  • Development: Retrogressive metamorphism.

Subphylum Cephalochordata

• Example: Branchiostoma (Amphioxus)
• Characteristics:
  • Notochord: Extends from head to tail throughout life.
  • Excretion: Protonephridia.
  • Respiration: Through body surface.

Subphylum Vertebrata

• **Notochord replaced by vertebral column.
• Heart: Two, three, or four chambers.
• Kidneys: For excretion.

Classification of Vertebrata

• Superclass Agnatha (Jawless): Cyclostomata (e.g., lamprey)
• Superclass Gnathostomata (Jawed): Divided into Piscs (fishes) and Tetrapoda.

Class Cyclostomata

• Example: Lamprey (Petromyzon), Hagfish (Myxine)
• Characteristics:
  • Marine but migratory for spawning in freshwater.
  • Body: Elongated, lacking scales, paired fins absent.

Superclass Pisces (Fishes)

• Characteristics:
  • True fishes with paired (pectoral, pelvic) and unpaired (dorsal, ventral, caudal) fins.
  • Scales: Placoid in cartilaginous fish (Chondrichthyes), cycloid or ctenoid in bony fish (Osteichthyes).
  • Respiration: By gills; Air bladder in bony fish for buoyancy.

Class Chondrichthyes (Cartilaginous Fishes)

• Example: Shark (Scoliodon), Stingray (Trigon)
• Characteristics:
  • Marine habitat.
  • Cartilaginous skeleton, ventral mouth.
  • Ureotelic.
  • Internal fertilization, viviparous.

Class Osteichthyes (Bony Fishes)

• Example: Rohu (Labeo), Flying Fish (Exocoetus)
• Characteristics:
  • Freshwater or marine.
  • Bony skeleton, air bladder.
  • Ammonotelic.
  • External fertilization, oviparous.

Class Amphibia

• Example: Frog (Rana), Salamander
• Characteristics:
  • Life in water and land, eggs laid in water.
  • Moist skin, eyelids present.
  • Three-chambered heart.
  • External fertilization.

Class Reptilia

• Example: Snake (Naja), Crocodile (Crocodilus)
• Characteristics:
  • Terrestrial; scales.
  • Three-chambered heart (four in crocodile).
  • Internal fertilization, oviparous.

Class Aves

• Example: Sparrow (Passer), Penguin (Aptenodytes)
• Characteristics:
  • Feathers, beak, no teeth.
  • Four-chambered heart, homeothermic.
  • Internal fertilization, oviparous.

Class Mammalia

• Example: Human (Homo sapiens), Bat (Pteropus)
• Characteristics:
  • Mammary glands, hair
  • Four-chambered heart, homeothermic
  • Internal fertilization, viviparous

Homework

• Solve Previous Year Questions (PYQs) to reinforce understanding and application of concepts covered.