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Animal Classification: One Shot Revision

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Class 10
English

Animal Classification: One Shot Revision

Animal Classification

SSC Class 10 | Maharashtra Board | One Shot Revision



Slide 1: Introduction to Animal Diversity

  • There are approximately 7 million species of animals on Earth according to a recent study.
  • It is impossible to study each species individually.
  • Animal Classification: Grouping of animals into groups and sub-groups based on their similarities and differences.


Slide 2: Benefits of Animal Classification

  1. Easy to Study: Study of a few animals from a group helps understand the entire group.
  1. Evolutionary Understanding: Provides an idea about animal evolution from simple to complex.
  1. Accurate Identification: Animals can be identified with great accuracy (e.g., Identifying a Bat as a mammal, not a bird).
  1. Environmental Role: Helps understand the exact role of an animal in nature and its relationship with other living organisms.


Slide 3: Traditional Method of Classification

Historically, animals were classified into two sub-kingdoms based on the presence or absence of a notochord (a rod-like supporting structure).
fig 1: Traditional Method of Classification
fig 1: Traditional Method of Classification



Slide 4: Distinguish: Non-Chordates vs. Chordates

Feature
Non-Chordates
Chordates
Notochord
Absent
Present
Nerve Cord
Present on the Ventral side; it is paired and solid.
Present on the Dorsal side; it is single and hollow.
Gill Slits
Absent
Present at least in the embryonic stage.
Heart
If present, it is on the Dorsal side.
Always present on the Ventral side.


Slide 5: Criteria for Modern Classification

Modern classification uses a "New System" based on several biological parameters:
fig 2: Criteria for Modern Classification
fig 2: Criteria for Modern Classification



Slide 6: Body Symmetry

  1. Asymmetrical: Body cannot be divided into two equal halves by any imaginary axis (e.g., Sponges).
  1. Radial Symmetry: Body can be divided into two equal halves by any plane passing through the central axis (e.g., Starfish, Hydra).
  1. Bilateral Symmetry: Body can be divided into two equal halves only by one imaginary axis (e.g., Insects, Fish, Humans).
fig 3: Types of Body Symmetry
fig 3: Types of Body Symmetry



Slide 7: Germ Layers (Diploblastic & Triploblastic)

During embryonic development, layers of cells are formed which give rise to all tissues and organs.
  • Diploblastic: Only two layers (Ectoderm and Endoderm). Example: Cnidaria.
  • Triploblastic: Three layers (Ectoderm, Mesoderm, and Endoderm). Example: All phyla from Platyhelminthes onwards.
fig 4: Diploblastic vs Triploblastic Organization
fig 4: Diploblastic vs Triploblastic Organization



Slide 8: Body Cavity (Coelom)

  • Eucoelomate (True Coelom): Body cavity present between body wall and internal organs, lined by mesoderm (e.g., Annelida to Chordata).
  • Pseudocoelomate (False Coelom): Body cavity is present but not lined by mesoderm (e.g., Aschelminthes).
  • Acoelomate: Body cavity is absent (e.g., Porifera, Cnidaria, Platyhelminthes).
fig 5: Body Cavity Types
fig 5: Body Cavity Types



Slide 9: Phylum Porifera (Sponges)

  • Structure: Simplest body organization with numerous pores called Ostia (water intake) and Osculum (water exit).
  • Special Cells: Possess Choanocytes (collar cells) with flagella to create water current.
  • Habitat: Mostly marine, some are freshwater.
  • Movement: Sedentary (attached to a substrate, no locomotion).
  • Reproduction: Asexual (budding/fragmentation) and sexual.
  • Examples: Sycon, Euspongia (Bath sponge), Hyalonema.


Slide 10: Phylum Cnidaria / Coelenterata

  • Forms: Polyp (cylindrical, sedentary) or Medusa (umbrella-like, free-swimming).
  • Special Cells: Cnidoblasts on tentacles used for defense and paralyzing prey.
  • Symmetry: Radial.
  • Organization: Tissue grade, Diploblastic.
  • Examples: Hydra (Polyp), Aurelia (Jellyfish - Medusa), Physalia (Portuguese man-of-war).
fig 6: Jellyfish (Medusa form)
fig 6: Jellyfish (Medusa form)



Slide 11: Phylum Platyhelminthes (Flatworms)

  • Body Shape: Slender and leaf-like or ribbon-like flat body.
  • Lifestyle: Mostly Endoparasites; few are free-living.
  • Organization: Triploblastic, Acoelomate.
  • Special Feature: Hermaphrodite (male and female reproductive systems in the same body).
  • Examples: Planaria (Free-living), Liver fluke, Tapeworm.
fig 7: Planaria
fig 7: Planaria



Slide 12: Phylum Aschelminthes (Roundworms)

  • Body Shape: Long, thread-like or cylindrical; non-segmented.
  • Organization: Triploblastic, Pseudocoelomate.
  • Protection: Covered with a tough cuticle.
  • Lifestyle: Mostly parasites; can be free-living in soil/water.
  • Reproduction: Unisexual (Separate males and females).
  • Examples: Ascaris (Intestinal worm), Filarial worm (Elephantiasis), Loa loa (Eye worm).
fig 8: Ascaris
fig 8: Ascaris



Slide 13: Phylum Annelida (Segmented Worms)

  • Body Shape: Long, cylindrical, and divided into ring-like segments (metamerism).
  • Organization: Triploblastic, Eucoelomate (True coelom).
  • Locomotion: Setae, parapodia, or suckers.
  • Symmetry: Bilateral.
  • Examples: Earthworm, Leech (Ectoparasite), Nereis.
fig 9: Earthworm
fig 9: Earthworm



Slide 14: Phylum Arthropoda

  • Rank: Largest phylum in the animal kingdom.
  • Structure: Animals with jointed appendages (legs).
  • Exoskeleton: Tough, chitinous exoskeleton.
  • Habitat: Found in all possible habitats (air, land, water).
  • Segmentation: Body is segmented into head, thorax, and abdomen.
  • Examples: Cockroach, Crab, Spider, Scorpion, Butterfly.
fig 10: Cockroach
fig 10: Cockroach



Slide 15: Phylum Mollusca

  • Rank: Second largest phylum.
  • Body Type: Soft-bodied, slimy, non-segmented.
  • Structure: Divided into Head, Foot, and Visceral mass.
  • Mantle: Visceral mass is covered by a fold of skin called mantle.
  • Shell: Mantle secretes a hard calcareous shell (external or internal).
  • Examples: Snail, Octopus, Bivalve (Oyster).
fig 11: Octopus
fig 11: Octopus



Slide 16: Phylum Echinodermata

  • Meaning: Spiny-skinned animals.
  • Skeleton: Calcareous spines/plates on the skin.
  • Locomotion: Using Tube feet (part of water vascular system).
  • Symmetry: Bilateral in larvae; Radial (Pentaradial) in adults.
  • Regeneration: High power of regeneration.
  • Examples: Starfish, Sea urchin, Sea cucumber.
fig 12: Starfish
fig 12: Starfish



Slide 17: Phylum Hemichordata

  • Meaning: Half-chordates; considered a connecting link between non-chordates and chordates.
  • Structure: Body divided into Proboscis, Collar, and Trunk.
  • Notochord: Present only in the proboscis region.
  • Examples: Balanoglossus, Saccoglossus.
fig 13: Balanoglossus
fig 13: Balanoglossus



Slide 18: Phylum Chordata and Sub-phyla

Phylum Chordata is further divided into three sub-phyla:
fig 14: Classification of Chordata
fig 14: Classification of Chordata

  1. Urochordata: Notochord present only in tail of larva.
  1. Cephalochordata: Notochord throughout the body length.
  1. Vertebrata/Craniata: Notochord replaced by a vertebral column; Brain protected by a cranium (skull).


Slide 19: Classes of Vertebrata (Part 1)

1. Class Cyclostomata (Jawless Fish)

  • Jawless mouth with suckers.
  • Ectoparasites on other fish.
  • Soft skin without scales.
  • Example: Petromyzon.

2. Class Pisces (Fishes)

  • Cold-blooded (Poikilothermic): Body temp changes with environment.
  • Spindle-shaped body: Reduces water resistance.
  • Locomotion: Fins (paired and unpaired).
  • Respiration: Gills.
  • Examples: Rohu, Pomfret, Shark (Cartilaginous).

3. Class Amphibia

  • Larvae are aquatic (gills); Adults can be aquatic or terrestrial (lungs/skin).
  • Moist skin (no scales) used for breathing in water.
  • Two pairs of limbs; no neck.
  • Examples: Frog, Toad, Salamander.
fig 15: Frog
fig 15: Frog



Slide 20: Classes of Vertebrata (Part 2)

4. Class Reptilia

  • First true terrestrial vertebrates.
  • Creeping/Crawling movement (cannot lift body high).
  • Dry and scaly skin.
  • Neck is present.
  • Examples: Wall lizard, Snake, Tortoise.

5. Class Aves (Birds)

  • Warm-blooded (Homeothermic): Maintain constant body temp.
  • Forelimbs modified into wings for flight.
  • Exoskeleton of feathers; digits have scales and claws.
  • Jaws modified into a toothless beak.
  • Examples: Pigeon, Parrot, Peacock, Ostrich.

6. Class Mammalia

  • Defining feature: Presence of Mammary glands (milk-producing).
  • Body covered with hair/fur.
  • Warm-blooded; digits with nails, claws, or hoofs.
  • Examples: Human, Kangaroo, Elephant, Bat, Whale.
fig 16: Bat (Mammal)
fig 16: Bat (Mammal)



Slide 21: Summary and Important PYQs

  • Largest Phylum: Arthropoda.
  • Second Largest Phylum: Mollusca.
  • Connecting Link: Balanoglossus (Non-chordate to Chordate).
  • Water Vascular System: Echinodermata.
  • Collar Cells: Porifera.
  • Spindle Shape: Adaptation for aquatic/aerial life (Pisces, Aves).
Common Question: Why is a Whale a mammal and not a fish? Answer: Whales have lungs (not gills), they give birth to young ones (not eggs), and possess mammary glands.