Chapter 11: Animal Kingdom - Class 11 Biology

Chapter 11: Animal Kingdom - Class 11 Biology

• What are the characteristics of animals?

  • Heterotrophic nutrition
  • Multicellular eukaryotic organisms
  • Absence of chlorophyll
  • Motility in some stage of their life
  • Eukaryotic cells
  • Ability to reproduce sexually

• What are the different ways animals are classified?

  • Based on body symmetry (asymmetry, radial symmetry, bilateral symmetry)
  • Based on presence or absence of coelom (acoelomate, pseudocoelomate, coelomate)
  • Based on patterns of embryonic development (protostomes, deuterostomes)
  • Based on presence or absence of segmentation
  • Based on presence or absence of notochord
  • Presence or absence of a backbone (invertebrates and vertebrates).

Invertebrates

• Porifera (Sponges):

  • Multicellular, no true tissues or organs
  • Sessile (attached to a surface)
  • Spicules for support
  • Filter feeders
  • Example: Sycon, Spongilla, Euspongia

• Coelenterata (Cnidarians):

  • Radially symmetrical
  • Two germ layers (diploblastic)
  • Cnidocytes (stinging cells) for defense and capturing prey
  • Gastrovascular cavity
  • Example: Hydra, Obelia, Jellyfish, Sea anemones

• Platyhelminthes (Flatworms):

  • Bilaterally symmetrical
  • Acoelomate (no body cavity)
  • Triploblastic (three germ layers)
  • Flattened body
  • Example: Planaria, Fasciola (liver fluke), Taenia (tapeworm)

• Nematoda (Roundworms):

  • Bilaterally symmetrical
  • Pseudocoelomate
  • Cylindrical body
  • Complete digestive system
  • Example: Ascaris, Wuchereria

• Annelida (Segmented Worms):

  • Bilaterally symmetrical
  • Coelomate
  • Body segmented into metameres
  • Example: Earthworm, leech, Nereis

• Mollusca:

  • Bilaterally symmetrical
  • Coelomate
  • Soft body, often with a shell
  • Mantle cavity, muscular foot
  • Example: Snail, oyster, octopus, squid

• Arthropoda:

  • Largest phylum
  • Bilaterally symmetrical
  • Jointed appendages
  • Exoskeleton made of chitin
  • Segmented body
  • Example: Cockroach, spider, butterfly, crab

• Echinodermata:

  • Radially symmetrical (in adult form)
  • Deuterostomes
  • Water vascular system
  • Spiny skin
  • Example: Starfish, sea urchin, sea cucumber

• Hemichordata:

  • Marine animals
  • Bilaterally symmetrical
  • Dorsoventrally flattened
  • Example: Balanoglossus

Vertebrates

• Chordata:

  • Notochord
  • Dorsal hollow nerve cord
  • Pharyngeal slits
  • Post-anal tail
  • Divided into:
    • Pisces (Fishes):
      • Aquatic, water breathing, fins for locomotion
    • Amphibia:
      • Moist skin, undergo metamorphosis
      • Example: Frog, toad, salamander
    • Reptilia:
      • Scaly skin, lay amniotic eggs
      • Example: Snake, lizard, crocodile, turtle
    • Aves:
      • Feathers, lay amniotic eggs, have wings, forelimbs modified into wings
      • Example: Sparrow, owl, parrot, eagle
    • Mammalia:
      • Mammary glands, hair or fur, three middle ear bones, high metabolic rate, most viviparous
      • Example: Cat, dog, human, bat, whale

• Key characteristics distinguishing vertebrates from invertebrates

  • Presence of an internal skeleton (endoskeleton)
  • Presence of a backbone and a cranium (skull)
  • More developed nervous system

Important Concepts

• Phylogeny: the evolutionary history of a group of organisms

• Classification: arranging organisms into groups based on shared characteristics

• Evolutionary relationships: illustrating connections between organisms on a phylogenetic tree.

• Adaptive radiation: diversification of one species into multiple forms

• Animal diversity in different habitats of the Earth.

• Economic importance of animals (e.g., food, medicine, agriculture).

• Threats to various animal species (e.g., habitat loss, pollution).

• Conservation strategies to protect endangered animals.

Explore the fascinating features of the animal kingdom in this quiz based on Chapter 11 of Class 11 Biology. Test your knowledge on the characteristics of animals, their classifications, and specific groups like Porifera. Perfect for students preparing for biology exams!