Trochophore larva

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Comments:

It is the common larva for annelida and mollusca.

• In the development of Nereis, trochophore larva is formed after gastrulation.

• Larva is conical or top shaped, microscopic and fast swimmer.

• Anterior end contains apical sensory ongan having tuft of cilia. Nerve ganglion is present below it.

• Digestive system is complete consisting of lateral mouth, rounded sacular stomach, intestine and anus.

•There are three defined ciliated bands for swimming/locomotion through ciliary beats-

 (i) Pre-oral ciliated band or prototroch

(ii) Post oral ciliated band or metatroch.

(iii) Telotroch

•Internally larva contains coelom, larval nephridium (protonephridium), mesoderm, eye spot and larval muscles.  

Food groove is present between prototroch and metatroch. Ciliated organs guide food towards food groove which chanelise food into mouth.

In some cases, neurotroch is present at posterior end and acts as sensory organ.  

•After metamorphosis, trochophore larva changes into adult.






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