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Animal Kingdom Lecture Notes

Jul 10, 2024

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Animal Kingdom Lecture Notes

Introduction

  • Lecturer: Diksha Ma'am
  • Topic: Animal Kingdom (Chapter important for NEET)
  • Focus: NCERT-based; up to phylum for non-chordates, up to class for chordates

Characteristics of Animals

  • Multicellular: Made up of multiple cells
  • Heterotrophic: Cannot produce their own food
  • Holozoic: Engulf food through the mouth
  • Motion: Generally capable of movement
  • Exceptions: Sponges (no neurons or sense organs)

Classification of Animals

Importance of Classification

  • Similar features within a group (e.g., cockroach and ant in the same group)
  • Makes it easier to study groups rather than individual organisms

Basis for Classification

  • Level of Organization: Cellular, tissue, organ, organ system
  • Symmetry: Asymmetry, radial symmetry, bilateral symmetry
  • Germ Layers: Diploblastic (two layers), triploblastic (three layers)
  • Body Cavity (Coelom): Acoelomate, pseudocoelomate, coelomate
  • Segmentation: True segmentation (metamerism) vs false (pseudosegmentation)
  • Notochord: Presence (chordates) vs absence (non-chordates)

Phylums from Simplest to Complex

  1. Porifera
  2. Cnidaria (Coelenterata)
  3. Ctenophora
  4. Platyhelminthes
  5. Nematoda (Aschelminthes)
  6. Annelida
  7. Arthropoda
  8. Mollusca
  9. Echinodermata
  10. Hemichordata
  11. Chordata

Detailed Classification Criteria

Level of Organization

  1. Cellular Level: e.g., Sponges (Phylum Porifera)
  2. Tissue Level: e.g., Coelenterates (Cnidaria) and Ctenophores
  3. Organ Level: e.g., Flatworms (Platyhelminthes)
  4. Organ System Level: e.g., Nematodes to Chordates

Symmetry

  • Asymmetry: Sponges
  • Radial Symmetry: Cnidaria, Ctenophora, Echinodermata (adults)
  • Bilateral Symmetry: Annelida, Arthropoda, Chordata

Germ Layers

  • Diploblastic: Cnidaria, Ctenophora
  • Triploblastic: Platyhelminthes to Chordates

Coelom

  1. Acoelomate: No body cavity; e.g., Platyhelminthes
  2. Pseudocoelomate: False coelom; e.g., Nematoda
  3. Coelomate: True coelom; e.g., Annelida to Chordates

Segmentation

  1. True Segmentation (Metamerism): e.g., Annelida, Arthropoda, Chordata
  2. False Segmentation (Pseudometamerism): e.g., Tapeworms

Notochord

  • Chordates: Have notochord (e.g., vertebrates)
  • Non-Chordates: Do not have notochord (e.g., from Porifera to Hemichordata)

Phylum Porifera

  • Common Name: Sponges
  • Habitat: Mostly marine, some freshwater (e.g., Spongilla)
  • Body Plan: Pores (Ostia and Osculum), central cavity (Spongocoel)
  • Unique Features: Water canal system, collar cells (choanocytes)
  • Exoskeleton: Spicules and spongin fibers
  • Reproduction: Both sexual and asexual (budding, fragmentation)
  • Examples: Sycon, Spongilla, Euspongia

Phylum Cnidaria (Coelenterata)

  • Common Features: Aquatic, mostly marine, diploblastic, radial symmetry
  • Body Forms: Polyp and Medusa
  • Unique Cells: Cnidocytes (stinging cells)
  • Reproduction: Sexual and asexual (budding, fission); some show metagenesis
  • Examples: Hydra, Obelia, Physalia, Aurelia

Examples and Characteristics

  • Physalia: Portuguese Man of War
    • Adamsia: Sea Anemone
    • Pennatula: Sea Pen
    • Gorgonia: Sea Fan
    • Meandrina: Brain Coral

Phylum Ctenophora

  • Common Name: Comb jellies
  • Habitat: Marine
  • Unique Features: Bioluminescence, comb plates used for locomotion
  • Reproduction: Sexual only
  • Examples: Pleurobrachia, Ctenoplana

Phylum Platyhelminthes

  • Common Name: Flatworms
  • Body Plan: Dorsoventrally flattened, acoelomate
  • Habit: Mostly parasitic
  • Reproduction: Both sexual and asexual (planaria show regeneration)
  • Examples: Planaria, Taenia (tapeworm), Fasciola (liver fluke)

Phylum Nematoda (Aschelminthes)

  • Common Name: Roundworms
  • Body Plan: Cylindrical, pseudocoelomate
  • Habit: Free-living or parasitic
  • Reproduction: Sexual, distinct sexes
  • Examples: Ascaris, Wuchereria, Ancylostoma

Phylum Annelida

  • Common Name: Segmented worms
  • Body Plan: Metamerically segmented, coelomate
  • Habit: Aquatic, terrestrial, some parasitic
  • Excretion: Nephridia
  • Reproduction: Sexual (some show regeneration)
  • Examples: Earthworm, Leech

Phylum Arthropoda

  • Unique Features: Largest phylum, segmented body (head, thorax, abdomen), jointed appendages
  • Habit: Ubiquitous (found everywhere)
  • Excretion: Malpighian tubules
  • Reproduction: Sexual, distinct sexes
  • Examples: Cockroach, Butterfly, Prawn, Scorpion

Examples and Importance

  • Economically Important: Honeybee (Apis), Silkworm (Bombyx), Lac insect (Laccifer)
  • Vectors: Anopheles (malaria), Culex (filariasis), Aedes (dengue)
  • Gregarious Pest: Locust (Locusta)
  • Living Fossil: King Crab (Limulus)

Phylum Mollusca

  • Unique Features: Soft body, often with a calcareous shell
  • Body Plan: Head, muscular foot, visceral hump
  • Reproduction: Sexual, distinct sexes
  • Examples: Snail, Octopus, Pearl oyster

Examples and Characteristics

  • Pila: Apple snail
  • Pinctada: Pearl oyster
  • Sepia: Cuttlefish
  • Loligo: Squid
  • Octopus: Devil fish
  • Aplysia: Sea hare
  • Dentalium: Tusk shell
  • Chiton: Coat of mail shell

Phylum Echinodermata

  • Unique Features: Spiny skin, endoskeleton of calcareous ossicles
  • Habit: Marine
  • Symmetry: Adults radial, larvae bilateral
  • Reproduction: Sexual, external fertilization
  • Examples: Starfish, Sea urchin, Sea cucumber

Examples and Characteristics

  • Asterias: Starfish
  • Echinus: Sea urchin
  • Antedon: Sea lily
  • Cucumaria: Sea cucumber
  • Ophiura: Brittle star

Phylum Hemichordata

  • Unique Features: Worm-like, body divided into proboscis, collar, and trunk
  • Habit: Marine
  • Reproduction: Sexual, external fertilization
  • Examples: Balanoglossus, Saccoglossus

Phylum Chordata

  • Unique Features: Notochord, dorsal hollow nerve cord, pharyngeal gill slits, post-anal tail
  • Subphyla: Urochordata (Tunicates), Cephalochordata (Lancelets), Vertebrata

Subphylum Vertebrata

  1. Superclass Agnatha (Jawless)
    • Class Cyclostomata: e.g., Lampreys, Hagfish
  2. Superclass Gnathostomata (With jaws)
    • Class Chondrichthyes (Cartilaginous fishes): e.g., Sharks, Rays
    • Class Osteichthyes (Bony fishes): e.g., Rohu, Catla
    • Class Amphibia: e.g., Frogs, Salamanders
    • Class Reptilia: e.g., Turtles, Snakes
    • Class Aves (Birds): e.g., Sparrows, Eagles
    • Class Mammalia: e.g., Humans, Dogs

Homework

  • Task: Solve previous year questions (PYQs) on Animal Kingdom

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