Animal Kingdom - NEET Notes
Classification of Animal Kingdom
Animals are classified based on body organization, symmetry, germ layers,
coelom, segmentation, and mode of reproduction.
1. Basis of Classification
Level of Organization: Cellular (Porifera), Tissue (Cnidaria), Organ
(Platyhelminthes), Organ-system (higher phyla).
Body Symmetry:
o Asymmetrical: No symmetry (e.g., Porifera).
o Radial Symmetry: Body can be divided into identical halves
along any vertical plane (e.g., Cnidaria, Echinodermata).
o Bilateral Symmetry: Body divided into two equal halves along
a single plane (e.g., Arthropoda, Chordata).
Germ Layers:
o Diploblastic: Two germ layers - ectoderm & endoderm (e.g.,
Cnidaria).
o Triploblastic: Three germ layers - ectoderm, mesoderm &
endoderm (e.g., Platyhelminthes and above).
Coelom (Body Cavity):
o Acoelomate: No coelom (e.g., Platyhelminthes).
o Pseudocoelomate: False coelom (e.g., Nematoda).
o Coelomate: True coelom (e.g., Annelida and above).
Segmentation:
o Metameric segmentation: Repeating body segments (e.g.,
Annelida, Arthropoda).
o Non-segmented: No segmentation (e.g., Platyhelminthes,
Mollusca).
Major Phyla in the Animal Kingdom
1. Phylum Porifera (Sponges)
Characteristics: Cellular level of organization, asymmetrical, canal
system for water circulation.
Reproduction: Asexual (budding, fragmentation), sexual (internal
fertilization).
Examples: Sycon, Spongilla, Euspongia.
Classification of Animal Kingdom
Animals are classified based on body organization, symmetry, germ layers,
coelom, segmentation, and mode of reproduction.
1. Basis of Classification
Level of Organization: Cellular (Porifera), Tissue (Cnidaria), Organ
(Platyhelminthes), Organ-system (higher phyla).
Body Symmetry:
o Asymmetrical: No symmetry (e.g., Porifera).
o Radial Symmetry: Body can be divided into identical halves
along any vertical plane (e.g., Cnidaria, Echinodermata).
o Bilateral Symmetry: Body divided into two equal halves along
a single plane (e.g., Arthropoda, Chordata).
Germ Layers:
o Diploblastic: Two germ layers - ectoderm & endoderm (e.g.,
Cnidaria).
o Triploblastic: Three germ layers - ectoderm, mesoderm &
endoderm (e.g., Platyhelminthes and above).
Coelom (Body Cavity):
o Acoelomate: No coelom (e.g., Platyhelminthes).
o Pseudocoelomate: False coelom (e.g., Nematoda).
o Coelomate: True coelom (e.g., Annelida and above).
Segmentation:
o Metameric segmentation: Repeating body segments (e.g.,
Annelida, Arthropoda).
o Non-segmented: No segmentation (e.g., Platyhelminthes,
Mollusca).
Major Phyla in the Animal Kingdom
1. Phylum Porifera (Sponges)
Characteristics: Cellular level of organization, asymmetrical, canal
system for water circulation.
Reproduction: Asexual (budding, fragmentation), sexual (internal
fertilization).
Examples: Sycon, Spongilla, Euspongia.
