The Question is from neet-botany , and it was created by the author Mr. NARESH KUMAR K

Question

A newly discovered organism exhibits radial symmetry in its larval stage but bilateral symmetry as an adult.  Its body cavity is formed by splitting of the mesoderm.  It possesses a water vascular system.  To which phylum does this organism MOST likely belong?

Mr. NARESH KUMAR K · Accepted Answer

## CORE INFORMATION
✓ **Answer**: A
## CONCEPT FRAMEWORK
	**Primary Concept**: Animal Phyla Characteristics
	**Related Topics**: Invertebrate Zoology, Embryology, Symmetry, Coelom Formation
	**Prerequisites**: Understanding of basic animal classification and characteristics of major phyla.
## SOLUTION PATHWAY
**Given Information**:
	1. Radial symmetry in larval stage, bilateral symmetry in adult stage.
	2. Coelom formed by splitting of mesoderm (schizocoelom).
	3. Possesses a water vascular system.
**Method & Steps**:
	1. Analyze each characteristic and identify which phyla exhibit them.
		Reasoning: We need to find a phylum that matches all three given characteristics.
	2.  Focus on the unique characteristic: water vascular system.
		Working: This system is a defining feature of echinoderms.
		Key Point:  While other phyla may share some characteristics, the water vascular system pinpoints the correct phylum.
	3. Confirm that other characteristics align with Echinodermata.
		Result: Echinoderms exhibit radial symmetry in adults (and often bilateral in larvae), have a schizocoelom, and possess a water vascular system.
		Verification: All three given characteristics match the phylum Echinodermata.
## OPTION ANALYSIS
[A] ✓: Echinodermata - This phylum includes starfish, sea urchins, and sea cucumbers, which are known for their radial symmetry (in adults), schizocoelous body cavity, and unique water vascular system used for locomotion, feeding, and respiration. The larval stage often exhibits bilateral symmetry.
[B] :x: Chordata - Chordates (including vertebrates) are characterized by a notochord, dorsal nerve cord, pharyngeal slits, and post-anal tail. They have bilateral symmetry, a coelom, but no water vascular system.
[C] :x: Cnidaria - Cnidarians (like jellyfish and corals) exhibit radial symmetry, have a simple body plan with a gastrovascular cavity, but lack a true coelom. They do not have a water vascular system.
[D] :x: Annelida - Annelids (segmented worms) have bilateral symmetry, a true coelom (formed by schizocoely), but lack a water vascular system. They do not exhibit radial symmetry at any life stage.
## LEARNING AIDS
	**Common Mistakes**:
		1. Focusing on only one characteristic: Considering only radial symmetry might lead to choosing Cnidaria, but overlooking the other key features.
		2. Confusing larval and adult stages:  Remembering that echinoderms have bilateral larvae and radial adults is crucial.
	**Quick Tips**:
		1. Water vascular system is a hallmark of Echinodermata.
		2. Associate 'spiny skin' with Echinodermata (echino = spiny, derm = skin).

Mr. NARESH KUMAR K · Answer

The correct Option is "Echinodermata"

Mr. NARESH KUMAR K · Answer

Chordata

Mr. NARESH KUMAR K · Answer

Cnidaria

Mr. NARESH KUMAR K · Answer

Annelida

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