Echinoderms: Water Vascular System — NEET Biology
✅ Asked in NEET 2021Read the following statements: I. Metagenesis is observed in helminths. II. Echinoderms are triploblastic and coelomate. III. Roundworms have organ system level. IV. Water vascular system is characteristic of echinoderms. Choose the correct answer. NEET Year: NEET 2021
Read the following statements: I. Metagenesis is observed in helminths. II. Echinoderms are triploblastic and coelomate. III. Roundworms have organ system level. IV. Water vascular system is characteristic of echinoderms. Choose the correct answer. NEET Year: NEET 2021
Answer & NCERT explanation
Correct answer: D — II, III and IV
Statements II, III, and IV are correct. Echinoderms are triploblastic and coelomate (II). Roundworms have organ system level organization (III). Water vascular system is characteristic of echinoderms (IV). Statement I is wrong - metagenesis occurs in cnidarians, not helminths. This follows NCERT Animal Kingdom chapter.
Read more NCERT concept on the PYQ
These animals have an endoskeleton of calcareous ossicles and, hence, the name Echinodermata (Spiny bodied,). All are marine with organ-system level of organisation. The adult echinoderms are radially symmetrical but larvae are bilaterally symmetrical. They are triploblastic and coelomate animals. Digestive system is complete with mouth on the lower (ventral) side and anus on the upper (dorsal) side. The most distinctive feature of echinoderms is the presence of water vascular system which helps in locomotion, capture and transport of food and respiration. An excretory system is absent. Sexes are separate. Reproduction is sexual. Fertilisation is usually external. Development is indirect with free-swimming larva.
NTA tests students on the unique characteristics of echinoderms, especially the water vascular system that distinguishes them from other phyla. This system functions in locomotion, feeding, and respiration—a triple role students often forget. A common mistake is confusing echinoderms with other coelom animals or thinking their radial symmetry applies to larvae too (larvae are actually bilateral). Remember: adult echinoderms are radially symmetrical, have calcareous ossicles, and lack an excretory system. The water vascular system with tube feet is their defining feature—it's what NTA consistently focuses on because it's unique to this phylum and fundamental to understanding their ecology.
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