Characteristics of orders-3-ANASPIDEA,4-PTEROPODA,5-ACOCHILIDIACEA of subclass OPISTHOBRANCHIA

Order3:- ANASPIDEA

1) They are mostly found in tropica; and subtropical 
     waters.

2) They have small shell more or less covered by 
     mantle.

3) They have well developed Parapodial lobes.

4) The anterior end of these animals bears a pair of  

     tentacles ,a pair of rhinophores and a pair eyes.

5) The sperm duct opens to the penis located    
     anteriorly after running through the body length.

     Examples:-Aplysia, Akera.

Aplysia californica

Aplysia

                 

Alkera

                    



Order4:- -PTEROPODA

1) They include Pelagic snails with or without   
    shell.

2) They swim by a pair of lateral expansions.

                            3) They are protandrous , hermaphrodite with   
                                an  open sperm  groove.

                               Examples:-Spiratella, Cavolina, Peraclis, Clione.

                          

Spiratella

Cavolina

   

            











Order5:- ACOCHILIDIACEA

     

1)They are minute without shell or naked snail.

2) They have gills ,parapodia and visceral sac  

     projecting  behind the foot.

3) They may be monoecious or dioecious.

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