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#bivalves

3 public questions tagged with this topic.

Animal Classification

Brachiopods differ from bivalve molluscs because their shells are

Both Brachiopoda and Bivalvia display superficially similar bivalved shells leading to historical confusion yet fundamentally differ in symmetry, orientation and anatomy. Brachiopod valves occupy dorsal and ventral positions, inequivalve, plane bilateral symmetry bisecting each valve medianly, valves not mirror images. Bivalve valves are left and right lateral usually equivalve mirror images with symmetry between valves. Brachiopod shell may be chitinophosphatic or low-magnesium calcite punctate, unlike nacreous aragonite typical bivalves, reflecting independent evolutionary origin of shell se

Ref: Brusca & Brusca, Chapter 22: Brachiopoda vs Bivalvia dorsal ventral valves orientation

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Animal Classification

Veliger larva is typical of

Veliger represents characteristic free-swimming planktotrophic larva of marine molluscs, directly derived from trochophore via development of expanded ciliated velum. It possesses two large ciliated lobes forming velum for swimming and particle capture, together with developing foot, mantle secreting protoconch, shell gland and visceral anlage. Commonly found in Gastropoda, Bivalvia and Scaphopoda, while Cephalopoda and many freshwater gastropods lost it through direct development with yolky eggs. Trochophore precedes veliger, connecting annelid-mollusc shared ancestry within Spiralia, indicat

Ref: NCERT Class 11 Biology, Chapter 4; Brusca & Brusca, Invertebrates, Chapter 16: Molluscan larvae

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Animal Classification

Lamellibranchs are also known as

Bivalvia were historically called Lamellibranchiata due to distinctive plate-like lamellar gills adapted for respiration and filter feeding. They display two lateral calcareous valves hinged dorsally, laterally compressed body, loss of distinct head and radula, expansive mantle forming large branchial chamber. Ctenidia enlarge into W-shaped demibranchs with ciliary tracts enabling high water pumping. Synonym Pelecypoda reflects hatchet-like foot for burrowing. Thus lamellibranch directly corresponds to class Bivalvia within Conchifera among molluscs historically defined by characteristic gill

Ref: Brusca & Brusca, Invertebrates, 3rd ed., Chapter 16: Mollusca - Bivalvia classification

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