Animal kingdom

MIND MAP FOR NEET ASPIRANTS

ANIMAL KINGDOM

Classification

  • All animals are placed under Kingdom Animalia.

  • Characteristics:

    • Multicellular

    • Heterotrophic

  • Kingdom classified into 11 Phylums:

    1. Porifera

    2. Coelenterata

    3. Ctenophora

    4. Platyhelminthes

    5. Aschelminthes

    6. Annelida

    7. Arthropoda

    8. Mollusca

    9. Echinodermata

    10. Hemichordata

    11. Chordata

Body Organization Levels

  • Primitive Animals:

    • 1. Porifera: Cellular Level

    • 2. Coelenterata: Tissue Level

  • Advanced Animals:

    • 3. Ctenophora: Organ Level

    • 4. Platyhelminthes: Organ System

    • 5. Aschelminthes: Organ System

    • 6. Annelida: Organ System

    • 7. Arthropoda: Organ System

    • 8. Mollusca: Organ System

    • 9. Echinodermata: Organ System

    1. Hemichordata: Organ System

    1. Chordata: Organ System

Germinal Body Layers and Symmetry

  • Porifera: Not true symmetry

  • Ctenophora:

    • Two Germinal Layers

    • Asymmetry

  • Platyhelminthes:

    • Three Germinal Layers

    • Bilateral Symmetry

  • Aschelminthes:

    • Three Germinal Layers

    • Bilateral Symmetry

  • Annelida:

    • Three Germinal Layers

    • Bilateral Symmetry

  • Arthropoda:

    • Three Germinal Layers

    • Bilateral Symmetry

  • Mollusca:

    • Three Germinal Layers

    • Bilateral Symmetry

  • Echinodermata:

    • Three Germinal Layers

    • Radial (Adult), Bilateral (Larva)

  • Hemichordata:

    • Three Germinal Layers

    • Bilateral Symmetry

  • Chordata:

    • Three Germinal Layers

    • Bilateral Symmetry

Body Cavity Types

  • Types of Cavity:

    • Porifera: No cavity

    • Cnidaria & Ctenophora: Gastrovascular cavity

    • Platyhelminthes: Acoelomate

    • Aschelminthes: Pseudocoelomate

    • Annelida, Arthropoda, Mollusca, Echinodermata, Hemichordata, Chordata: Coelomate

Types of Digestion

  • Intracellular digestion: Porifera

  • Extracellular digestion: Platyhelminthes, Aschelminthes, Annelida, Arthropoda, Mollusca, Echinodermata, Hemichordata, Chordata

  • Incomplete digestion in Aschelminthes; Complete digestion in others.

Blood Circulation Types

  1. Porifera: None

  2. Coelenterata: None

  3. Ctenophora: None

  4. Platyhelminthes: None

  5. Aschelminthes: None

  6. Annelida: Closed

  7. Arthropoda: Open

  8. Mollusca: Open

  9. Echinodermata: Open

  10. Hemichordata: Open

  11. Chordata: Closed

Sexual Reproduction

  • Fertilization Conditions:

    • Porifera: External

    • Coelenterata: External

    • Ctenophora: External

    • Platyhelminthes: Mostly Bisexual, Sexual

    • Aschelminthes: Unisexual and external

    • Annelida: Bisexual, Internal/External

    • Arthropoda: Bisexual, External

    • Mollusca: Mostly Unisexual, Internal

    • Echinodermata: External

    • Hemichordata: External

    • Chordata: Internal

PHYLUM - PORIFERA (SPONGES)

  • Primitive multicellular animals.

  • Mostly marine.

  • Unique Characteristics:

    • Choanocytes and water canal system.

  • Water Entry:

    • Ostia (Inlets) allow H₂O to enter.

    • Water exits through Osculum.

  • Cell Types:

    • Choanoderm/Collar Cells: Flagellated for intracellular digestion.

    • Amoeboid Cells: Found in Mesenchyme.

    • Skeleton composed of spicules and spongin fibers.

  • Examples:

    • Sycon (Scypha)

    • Euplectella (Venous flower basket)

    • Euspongia (Bath sponge)

    • Spongilla (Fresh water sponge)

PHYLUM - COELENTERATA (CNIDARIA)

  • Mostly marine organisms with unique features:

    • Presence of coelenteron cavity (gastrovascular cavity).

    • Presence of cnidoblast cells (sting cells).

  • Functions include:

    • Capturing and anchoring food.

    • Defense.

Body Forms

  • Body Types:

    • Two basic forms: Polyp (sessile) and Medusa (free-living).

  • Examples:

    • Polyp: Hydra, Sea Anemones, Corals.

    • Medusa: Aurelia (Jellyfish).

  • Dimorphism examples include:

    • Hydra (asexual), Obelia (metagenesis), Adamsia (Sea Anemone), and Physalia (Portuguese man of war).

  • Exoskeleton in some species, such as corals.

PHYLUM - CTENOPHORA (COMB JELLY)

  • Exclusively marine; also called sea walnuts.

  • Characteristics:

    • Emit light (bioluminescence).

    • 8 external ciliated comb plates aiding locomotion.

  • Reproduction is exclusively sexual with indirect development; the larva stage is Cydippid.

  • Examples:

    • Pleurobrachia (Sea Gooseberry)

    • Ctenoplana.

PHYLUM - PLATYHELMINTHES (FLATWORMS)

  • Dorsally flattened bodies, mostly endoparasitic.

  • Characteristics:

    • Hooks and suckers for attachment to host.

    • Osmoregulation and excretion through flame cells/protonephridia.

  • Examples:

    • Planaria (free-living)

    • Fasciola (Liver Fluke)

    • Taenia (Tapeworm).

PHYLUM - ASCHELMENTHES (ROUND WORMS)

  • Circular cross-section.

  • Habitat varies; can be free-living or parasitic.

  • Complete digestive system with well-developed muscular pharynx.

  • Excretion by excretory tubes/rennet cells; females generally larger.

  • Examples:

    • Rhabditis (free-living)

    • Wuchereria (Filarial worm)

    • Ascaris (Roundworm)

    • Ancylostoma (Hookworm).

PHYLUM - ANNELIDA

  • Life forms are aquatic (marine/freshwater) or terrestrial.

  • Characteristics:

    • Free-living or parasitic.

    • Respiration through moist skin.

    • Locomotion via longitudinal and circular muscles.

    • Excretion through nephridia.

  • Examples:

    • Nereis (marine annelid)

    • Pheretima (Earthworm)

    • Hirudinaria (Leech).

PHYLUM - ARTHROPODA

  • Largest phylum; characterized by jointed appendages and chitinous exoskeleton.

  • Body divided into head, thorax, abdomen (e.g., Insects).

  • Respiration via tracheal system (insects), book lungs and gills (arachnids/crustaceans).

  • Excretion through Malpighian tubules or green glands.

  • Sensory organs: antennae, eyes, and statocysts.

Examples of Arthropods

  1. Insects: Apis (Honeybee), Bombyx (Silkworm), and disease vectors like Aedes (mosquito).

  2. Living Fossils: Limulus (King Crab).

  3. Arachnids: Scorpions.

  4. Crustaceans: Prawns.

PHYLUM - MOLLUSCA

  • Second largest phylum; soft-bodied animals, both terrestrial and aquatic.

  • Body consists of head, muscular foot, and visceral hump.

  • Unique features:

    • Radula (rasping organ for feeding).

    • Gills for respiration.

  • Examples:

    • Pila (Apple snail)

    • Pinctada (Pearl oyster)

    • Aplysia (Sea hare)

    • Sepia (Cuttlefish)

    • Octopus (Devil fish).

PHYLUM - ECHINODERMATA

  • Spiny-bodied animals, exclusively marine.

  • Unique features:

    • Water vascular system aiding in locomotion and food capture.

    • Complete digestive system with mouth on ventral side and anus on dorsal side.

  • Examples:

    • Asterias (Starfish)

    • Echinus (Sea Urchin)

    • Cucumaria (Sea cucumber).

PHYLUM - HEMICHORDATA

  • Small group of marine animals resembling worms with a false notochord.

  • Structure includes:

    • Proboscis, collar, and trunk region with gill slits for respiration.

  • Examples:

    • Balanoglossus

    • Saccoglossus.

PHYLUM - CHORDATA

  • Characteristics distinguishing Chordates from non-Chordates:

    • Presence of notochord, dorsal hollow kidney, and gill slits.

    • Chordates have a ventral heart and post-anal tail.

Subphyla of Chordata

  1. Urochordata (Tunicata): Notochord present only in larval tail.

  2. Cephalochordata: Lancelets retain notochord throughout life.

  3. Vertebrata: Notochord replaced by vertebral column in adults.

Classes of Vertebrata

  1. Cyclostomata: Ectoparasites, jawless, with gill slits.

    • Examples: Petromyzon (Lamprey), Myxine (Hagfish).

  2. Chondrichthyes: Cartilaginous fish, internal fertilization, ampullae of Lorenzini.

    • Examples: Carcharodon (Great white shark), Trygon (Stingray).

  3. Osteichthyes: Bony fish with external fertilization.

    • Examples: Hippocampus (Sea horse), Catla (Fish).

  4. Amphibia: Dual life - aquatic and terrestrial.

    • Examples: Bufo (Toad), Rana (Frog).

  5. Reptilia: Mostly terrestrial with dry skin.

    • Examples: Chelone (Turtle), Chameleon (Lizard).

  6. Aves: Feathers, hollow bones, and internal fertilization.

    • Examples: Corvus (Crow), Struthio (Ostrich).

  7. Mammalia: Mammary glands, four-chambered heart, fur/hairs.

    • Examples: Macropus (Kangaroo), Canis (Dog).

Summary

  • Classification of animal kingdom is crucial for understanding diversity.

  • Each phylum has unique characteristics that differentiate them from others, aiding in identification and study.

  • Understanding basic anatomy and physiology of these phyla is essential for NEET aspirants covering zoology topics.