larva form of echinoderms, for long question note +3 zoology students BIOLOGY CLASSES

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Larval   Form   Of   Echinoderm



- The development of echinoderm may be direct or indirect.
- The direct development there is no larval form but in indirect development there are larval forms.
- Larval form are different parents.

1. DIPLEURUAL   LARVA
-  It is a foundamental larva of all echinoderm.
-  It is a microscoping and free swiming larva.
-  Body is egg-shaped / oval and bilateralaly symmetrical.
-  dipleurla 2 cillia bands named as
a. Perioral band: used for locomotion.
b. Adoral band: used for collecting of food.
-  Dipleurual larva developes in next larva named as Bipinaria larva.

2.BIPINARIA   LARVA
-  It is a 2nd  larva stage of star fish / asteroidea.
-  It is a minute and microscopic and free swinminh larva.
- The body is bilateral symmetrical.
-  It has straight elimentary canal , mouth to anus.
-  Body has a no. Of out  growth called as arm.
-  It has 2 unpairs arms and 5 paired arms.
-  The arms are ,
1. Postero – Lateral ------ 2
2. Postero – Dorsal  ------ 2
3. Post      -- Oral      ------ 2
4. Pre        -- Oral      ------ 2
5. Antero – Dorsal   ------ 2
6. Ventro – Median ------ 1
7. Dorsal – Median ------- 1

3.BRACHIOLARIA   LARVA
-  It is the 3rd larva of starfish.
-  It is bilaterally symmetrical larva.
-  It shows 3 brachiolar arms with suckers , they are one median and two lateral in position.
-  Arms are helpful for swimmng and feeding.

4. OPHIPLUTEUS   LARVA
-  It is the larva of ophiuroidea and petorl.
-  Their is a single ciliated band present .
-  The all arms are supported by calcareous skeletal rods.
-  The larva has a pair of peroral arms and pair of postera dersal arm and a pair of postero latoral arm.
-  The postero lateral arm are always larger and directed forword direction , so this larva look like V  shaped.

5. AURICULARIA   LARVA
-  It is larva of sea cucumber.
-  It is bilateraly symmetricaly.
-  The present lobe is wall formed.
-  It is a single ciliated band.
-  The calcareous rods replaced by star-shaped or whell- like bodies.
-  The auricularia larva is transformed into a dolialaria larva.

6. DOLIOLARIA   LARVA
-  It is the larva of see lily.
-  The body is barrel shaped and bilaterally symmetrical.
-  The preoral lobe well-developed.
-  The body has 4 or 5 ciliary bond.
-  A mouth is present between second and thried ciliary band.
-  It is a free swimming larva.

7.PENTACRENOID LARVA
-  It is the 2nd larva of antedone.
-  It develops form daliolaria larva.
-  It looks like sea lily.
-  The pentactula larva , it has five tentacles around the mouth.
-  During the metamorphosis the crown develops.

8.METAMORPHOSIS
-  During the metomorphosis the bilaterally symmetrical larva become transformed into radially symmetrial adult and alternation of the position of the mouth.



9.SINGNIFICANCE
-  All the larva of echinoderms have bilateraly symmetry hence, it is beleved that the ansector of echinoderms was a bilateraly symmetrical animals.
-  A/C sea- man this ansector was called pentactual and it is universaly ascepted.
-  Radial symmetry of echinoderm is secondary but in cilientraltes and poriphera is primery.





*      Prof.- Dr ramakant pradhan 

best of luck for your exam , you study and ask u dout or other wise doubt in other long question in biology ask me in comment box .ok  student by . 



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