ANIMALIA

General Characteristics

• Largest phylum in animal kingdom
• Organ system organisation present
• Bilateral symmetry, triploblastic, coelomate (in higher groups)

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Non-Chordates

Porifera

• Cellular level organisation, diploblastic, acoelomate
• Body has pores, hence called sponges
• Non-mobile, aquatic organisms
• Examples: Scycon, Euplectella, Spongilla

Cnidaria / Coelenterata

• Tissue level organisation, diploblastic, acoelomate
• Radial symmetry, anus absent
• Aquatic, exoskeleton of calcium carbonate
• Examples: Jellyfish, Coral, Hydra

Platyhelminthes

• Organ level organisation, bilateral symmetry
• Triploblastic, acoelomate
• Body dorsoventrally flattened, parasitic/free-living
• Examples: Planaria, Liver fluke, Tapeworm

Nematoda (Aschelminthes)

• Triploblastic, pseudocoelom, bilateral symmetry
• Body cylindrical, sexes separate
• Found as intestinal worms
• Example: Filarial worm (Elephantiasis)

Annelida

• Organ system level, bilateral symmetry
• Triploblastic, coelomate, segmented body
• Locomotion by parapodia (e.g., Nereis)
• Examples: Earthworm, Leech

Arthropoda

• Largest phylum, segmented body (head, thorax, abdomen)
• Exoskeleton of chitin, open circulatory system
• Jointed appendages present
• Examples: Spider, Crab, Crayfish

Mollusca

• Triploblastic, coelomate, bilateral symmetry
• Hard exoskeleton (shell)
• Open circulatory system
• Examples: Octopus, Pila, Unio, Snail

Echinodermata

• Radial symmetry, triploblastic, coelomate
• Spiny-skinned, no segmentation
• Body shapes: star, spherical, elongated
• Examples: Starfish, Sea urchin, Brittle star

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Chordates

Protochordata

• Notochord present, paired gill slits
• Closed circulatory system, nerve cord present

Vertebrata

Cyclostomata (Jawless vertebrates)

• Jawless, primitive vertebrates
• Examples: Petromyzon, Myxine (lamprey)

Pisces (Fishes)

• 2-chambered heart
• Respiration through gills, mucous glands in skin
• Examples: Shark, Dogfish, Tuna

Amphibia

• 3-chambered heart, cold-blooded
• Live in water and land
• Examples: Frog, Toad, Salamander

Reptilia

• Cold-blooded, 3-chambered heart
• Exception: Crocodile → 4-chambered heart
• Examples: Snake, Turtle, Lizard, Crocodile

Aves (Birds)

• Warm-blooded, 4-chambered heart
• Body with head, thorax, abdomen, lay eggs

Mammalia

• Warm-blooded, 4-chambered heart
• Mammary glands present
• Examples: Human, Whale, Dolphin
• Exception: Egg-laying mammals → Platypus, Echidna

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Memory Tricks 🧠

• Non-chordates order:
  “Poor Cats Play Near A Muddy Area Every Day”
  (Porifera → Cnidaria → Platyhelminthes → Nematoda → Annelida → Arthropoda → Mollusca → Echinodermata)
• Vertebrates order:
  “Cold People Always Require Big Meals”
  (Cyclostomata → Pisces → Amphibia → Reptilia → Birds → Mammals)
• Heart chambers:
  Fish-2, Amphibian-3, Reptile-3 (Croc-4), Birds & Mammals-4