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🔬 Biology  ·  Animal Kingdom  ·  NEET

Which of these features is shared by both Annelida and Arthropoda?

Answer: Metameric segmentation of the body.

  • A Open circulatory system in both
  • B Metameric segmentation of the body
  • C Absence of a coelom
  • D Exoskeleton made of chitin in both

Correct answer: B. Metameric segmentation of the body

Explanation: Both Annelida and Arthropoda show metameric segmentation (repetition of body segments), though Annelida has a closed circulatory system while Arthropoda has an open one, and only Arthropoda has a chitinous exoskeleton.

Body Plan Progression Across PhylaPoriferaasymmetricalcellular levelCnidariaradial, diploblastictissue levelPlatyhelminthesbilateral, acoelomateorgan levelNematodapseudocoel.Annelida+true coelomorgan systemEach step adds organisational complexity: symmetry → germ layers → coelom type → organ systems

Moving across the animal phyla, body organisation becomes progressively more complex: from no symmetry and cellular organisation (Porifera) through radial/diploblastic (Cnidaria), bilateral/acoelomate (Platyhelminthes), pseudocoelomate (Nematoda), to a true coelom with full organ systems (Annelida and beyond).

Concept context

Phylum-level classification of the animal kingdom from Porifera to Chordata, based on body symmetry, coelom, and segmentation. One of the most example-heavy chapters for NEET.

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