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#ctenophores

4 public questions tagged with this topic.

Animal Classification

Larva of ctenophores is called

Ctenophore embryogenesis indirect in most planktonic species fertilized egg undergoes biradial cleavage hatches into characteristic cydippid larva free-swimming ovoid transparent form resembling miniature adult Order Cydippida with pair long branched tentacles housed within lateral sheaths eight rudimentary comb rows beating apical statocyst present at aboral pole. Cydippid serves as both larval stage and ancestral morphotype reflecting primitive biradial architecture from which lobate ribbon and beroid forms derive through growth. Some lobate retain cydippid features into juvenile stage few s

Ref: Brusca & Brusca, Chapter 9: Ctenophora cydippid larva; Campbell Biology, Ctenophore development

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Animal Classification

Complete gut with anal pores is present in

Contrasting with cnidarians possessing blind sac gastrovascular cavity with single opening, ctenophores exhibit through gut considered complete alimentary canal with distinct mouth at oral pole leading to pharynx stomach and canals extending meridionally beneath comb rows distributing nutrients and two aboral anal pores near apical organ expelling residues. Food enters via mouth after capture digested in stomach extracellularly intracellularly via phagocytes circulated through canals. Presence anal pores allows separate egestion enabling unidirectional processing more efficient than cnidarian

Ref: NCERT Class 11 Biology, Chapter 4: Ctenophora complete gut anal pores; Campbell Biology

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Animal Classification

Adhesive prey-capturing cells of ctenophores are

Ctenophores capture zooplankton prey not through nematocysts like cnidarians but via adhesive cells termed colloblasts located on pair long retractile tentacles present in Tentaculata absent in Nuda such as Beroe which feed by swallowing prey whole. Each colloblast comprises spiral filament coiled around core adhesive granules secreting sticky glue. Upon contact granules release adhesive tethering victim spiral uncoils absorbing energy. Tentacle retracts moving prey toward oral groove. Mechanism distinct from nematocyst piercing reflecting independent evolution planktonic predator capture stra

Ref: NCERT Class 11 Biology, Chapter 4: Ctenophora colloblasts; Campbell Biology, Chapter 33

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Animal Classification

Comb plates are characteristic of

Ctenophora known as comb jellies recognized by eight longitudinal meridional rows of ciliary comb plates called ctenes composed of fused macrocilia stacked as transverse combs beating coordinated metachronal waves for ciliary locomotion through viscous propulsion rather than muscular pulsation. Plates diffract light producing iridescent effect. Each row forms effective paddle. Unique to phylum inspiring name cteno comb and phora bearing. Absent in cnidarians which employ muscular contraction. Some benthic ctenophores secondarily lost combs as adaptation to creeping lifestyle on substrate feedi

Ref: NCERT Class 11 Biology, Chapter 4: Ctenophora comb plates ctenes; Campbell Biology Chapter 33

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