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#mollusca

9 public questions tagged with this topic.

ZOOLOGY

Which of the following is the primary function of the radula in Mollusca?

The radula is a rasping, file-like structure in mollusks used for scraping and ingesting food. This follows from latest NCERT 2026-27 principle explaining the concept clearly for NEET students in simple steps as per rationalized syllabus.

Ref: NCERT Biology Textbook - Latest Edition for Academic Session 2026-27 (Zoology section, Rationalized Textbook for Class XI and XII), Chapter: Biology - Zoology portion (Latest NCERT Textbooks for Academic Session 2026-27 - Rationalized Edition for Class XI and XII), Topic: Structural organization, ph

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Animal Classification

Radula is absent in which class of Mollusca?

Radula, chitinous toothed ribbon supported by odontophore cartilage and protracted by buccal muscles for rasping food, occurs in most molluscan classes including Gastropoda snails, Cephalopoda squids with beak and radula, Polyplacophora chitons with massive radula for algal grazing, but is absent in Bivalvia where head is reduced, buccal apparatus lost and feeding adapted to ctenidial filter feeding via inhalant siphon trapping particles on gill mucus. Absence correlates with sedentary infaunal lifestyle, loss of cephalization and evolutionary shift to suspension feeding, making radula absence

Ref: Hickman et al., Chapter 17: Radula Bivalvia Absence; Campbell Biology, 12th ed., Chapter 33, Feeding

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Animal Classification

The unique molluscan body plan includes foot, mantle and

Molluscan body plan consists of three main regions: muscular ventral foot used for creeping locomotion, burrowing and attachment, dorsal visceral mass containing digestive gland, heart, gonads and kidney, and mantle or pallium enveloping visceral mass dorsally, secreting shell and delimiting mantle cavity housing ctenidia for respiration and chemoreception. Shell is mantle product, not independent body region, radula is feeding organ within buccal mass. Visceral mass often undergoes torsion in gastropods. This foot-mantle-visceral mass triad represents conserved synapomorphy uniting all mollus

Ref: NCERT Class 11 Biology, Chapter 4: Mollusca Body Plan; Brusca & Brusca, Chapter 20, Organization

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Animal Classification

The basic molluscan larva is known as

Trochophore is free-swimming ciliated larva considered basal for Spiralia, exhibiting apical sensory tuft, equatorial prototroch ciliary band anterior to mouth for swimming and feeding, metatroch, telotroch posterior, complete gut with anus and pair of protonephridia for excretion. In molluscan development, trochophore appears in polyplacophorans and some bivalves before transforming into veliger larva bearing foot, shell gland and mantle. Planula typifies cnidarians, nauplius crustaceans. Presence of trochophore in molluscs supports lophotrochozoan affiliation with annelids sharing spiral cle

Ref: Campbell Biology, 12th ed., Chapter 33: Trochophore Mollusca; NCERT Class 11, Chapter 4, Mollusca

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