Characteristics of orders-9-NUDIBRANCHIA,10-RHODOPACEA,11-PYRAMIDELLACEA ,12-PARASITA of subclass OPISTHOBRANCHIA

Order 9:-NUDIBRANCHI

 1)They do not have or are naked

 2) They do not have internal gill or ctenidium an
    osphradium

 3) Mantle and mantle cavity is absent in them

 4) They respire by secondary branchiae which are usually

     arranged in circlet around the anus.


    Examples:-Doris, Tritonia, Armina, Eolis.   

Armina

 
Eolis 

Eolis

Order10:-RHODOPACEA 

  1) They are vermiform snail.

  2) They are without external appendages.

  3) They have nephridia of protonephridial type.

       Example:-Rhodope.  

Rhodope.

Order11:PYRAMIDELLACEA
  1) They have spirally twisted shell
  2) They have long invaginable proboscis.
  3) They do not have operculum.
  4) They do not have gills and radula. 
       Examples:-Turbonilla, Odostomia

Turbonilla,

Odostomia

Order12:- PARASITA

 1) They are endoparasitic gastropods found in the interior 
  of holothurians.

  2) They are extremely degenerated snails. 
Examples:-Entoconcha, Thyonicola

Entoconcha

Thyonicola

       






























   












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