Saturday, October 8, 2011

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






       






























   












Note: -To read about bacteria go to thallophytes.blogspot.com

Characteristics of orders-6-PHILILNOGLOSSACEA,7-SACCOGLOSSA,8-NOTASPIDEA of subclass OPISTHOBRANCHIA


Order6:- PHILILNOGLOSSACEA
             1) They are minute naked snail.
         2) They do not have head appendages.
         3) They do not have gills..
           4) They have visceral mass separated from the foot   
                only by a shallow groove.
                Example:- Philinoglossa.
Philinoglossa













Order7:- SACCOGLOSSA
               1)They may be with or without shell.
             2) They have suctorial type of Pharynx.
             3) They have closed type of sperm duct.
             4) They have Parapodia and cerata.
                Example:- Oxynoe.
oxynoe
oxynoe
























Order8:-NOTASPIDEA
1)They may or may not have shell.
2) They donot have Parapodia.
3) They have bipectinate gills and ospharadium on the right side.
4) They have mantle but devoid of mantle cavity.
   Examples:-Tylodina, Pleurobranchus.
Pleurobranchus.


                     















    Note: -To read about bacteria go to   thallophytes.blogspot.com

Friday, October 7, 2011

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.

               Note: -To read about bacteria go to   thallophytes.blogspot.com

Characteristics of order1-ONCHIDIACEA and order2-CEPHALASPIDEA of subclass-OPISTHOBRANCHIA


Order1-ONCHIDIACEA
1) They are slug-like, naked or without shell.
2) They have mantle which is projected widely beyond  
    the foot.
3) They have head with a pair retractile tentacles each  
     tipped with an eye.
4) Pulmonary sac ,anus and female gonopore located at 
     the posterior end.
5) They have male gonpore placed posteriorly.
  Examples:-Onchidium, Onchidella.
Onchidella nigricans

Onchidella celtica
 
     






















Order2-CEPHALASPIDEA 

1) They generally have shell but may be partly or wholly
    enclosed by mantle.
2) They may or maynot have Parapodial lobes.
3) They have head with tentacular shield.
Examples:-Acteon, Hydatina, Bulla
Bulla peasiana


Acteon tonatilis 









































Hydatina
















































Note : Read about bacteria in http\thallophytes.blogspot.com

Characteristics of subclass 2-OPISTHOBRANCHIA of Gastropoda


1) They are exclusively marine gastropods.
    2) They have reduced type of shell and when present 
         often covered with mantle or pedal folds.
    3) They do not have operculum usually.
    4) They have single gill or often replaced by secondary 
         branchiae in the form of dorsal outgrowth.
        5)They have heart with one auricle posterior to the
            ventricle.
        6)They have mantle cavity rotated to right side or often
             lost due to detorsion.
                7)They have nervous system concentrated due to
                    detorsion.
                8) They are hermaphrodite.
 Note: - Read about bacteria in http/thallophytes.blogspot.com

Characteristics of order3 –Stenoglossa of subclass-PROSB RANCHIA


1)They have shell with more or  elongated siphonal canal.
2)They have radula which consist of rows with two or three teeth in each rows.
  Examples: Murex, Magilus, Buccinum, Meulongena,Conus and Teregera.


 Conus geographus











Parts of Conus geographus










Murex


















Magilus
























NOTE:-To know about bacteria go to .thallophytes.blogspot.com
 

Wednesday, October 5, 2011

Characteristics of order2 –Mesogastropoda of sub class PROSOBRANCHIA


1)    They are the Prosobranchia with siphon, penis  and 
        non –calcified Operculum.
2)    They have radula of taenioglossare type with 7 teeth   
        in each row.
3)    They have one monopectinate gill.
4)    They have heart with one auricle.
5)    They have one ospharadium and  nephridium.
6)    They have nervous system concentrated without pedal cords.
Examples:-Viviparus, Ampullarius, Pila, Valvalata, Truncatella, Littorina, Hydrobia, Jonthina,Cypraea.
Viviparus








Ampullarius 

Ampullarius gigas














   
        
Cypraea
Hydrobia
Littorina

Littorina
Cypraea.

Cypraea.



 
         

Characteristics of order –Archaeogastropoda of sub class PROSOBRANCHIA


1) They are the Prosobranchia without proboscis, siphon,penis  
    and prosrratic glands.
2) Operculum is also present in many forms with few exception.
3) They have one or two bipectinate internal gills.
4)  They have heart mostly with two auricles.
5)  They usually have two osphradia.
6)  They have two nephridia.
7)  They have nervous system which is not concentrated and usually with two pedal cords.
8) They discharge the sex cells directly into the sea by the right nephridia.
Examples:-Haliotis, Fissurella, Acamaea, Patella, Trochus, Asteraea. Turbo.
        
Fissurella volcano


Patella

Trochus snail

                                                    

Characteristics of subclass of Mollusca-PROSOBRANCHIA


1)    They are mostly marine ,few freshwater or terrestrial forms.
2)    They have visceral mass twisted.
3)    They have mantle cavity which opens anteriorly in front of the visceral mass.
4)    They generally have conical and spirally coiled  shell with an operculum.
5)    They have distinct head with snout bearing a pair of tentacle and a pair of eyes.
6)    They have muscular foot that forms the ventral part of the body.
7)    They may have ctenidia or gills and if present are situated in the front of the heart.
8)    Sexes are separate

Characteristics of Mollusca’s class-GASTROPODA

1)    They are marine, freshwater, terrestrial and few parasitic on echinoderms. 
2)    They have unsegmented, asymmetrical  body with a univalve, spirally coiled shell. 
3)    They have distinct head with tentacles, eyes and mouth. 
4)    They have foot which is ventral, broad, flat and muscular forming the creeping sole and often bearing dorsally a hard piece, the operculum on its posterior end. 
5)    They have visceral mass spirally coiled exhibiting torsion. 
6)    Mantle is a collar-like fold of body wall, lining the body whorl leaving a space, the mantle cavity ,between itself and the body. 
7)    They have Buccal cavity containing an odontophore with radula bearing rows of chitinous teeth. 
8)    They have digestive system consisting of a muscular pharynx, long oesophagus, stomach, long coiled intestine and anteriorly placed anus. 
9)    Most of them respire through gills(ctenidia ) ,some of them through the wall of the mantle cavity and many by lungs. 
10) They have open circulatory system with heart enclosed Pericardium
11) They have excretory organs  consisting of metanephridia which are paired in primitive forms and reduced to a single nephridia in most forms.
12)They have nervous system comprising of distinct cerebral and pleural besides buccal, pedal, parietal and visceral ganglia.
13)Most of them have sexes in two bodies(dioecious) but few have both the sexes in same body.
14) The development  includes trochophore and veliger larval stage.                            

Brief of Mollusca’s class-GASTROPODA


              The word Gastropoda is derived from two Greek words gaster=belly and podos=foot. It has three subclass namely Prosobranchia ,Opisthobranchia and  Pulmonata.The subclass Prosobranchia has three orders. The three orders are as follow. a) order1:-Archaeogastropoda b)order2:-Mesogastropoda c)order3:-Stenoglossa
         The subclass Opisthobranchia has 11 orders. They are as follow .
a) order1:-Onchidiacea                       b)order2:-Cephalaspidea         
 c) order3:-Anaspidea or Aplysiacea  d) order4:-Pteropoda
e) order5:-Acochillidiacea                   f) order6:-Phililnoglossacea
g) order7:-Saccoglossa                         h) order8:-Notaspidea
i) order9:-Nudibranchia                        j) order10:-Rhodopacea
k)order11:-Pyramidellacea                       
 The subclass Pulmonata has two orders namely as
a) order1:-Bassommatophora   b) order2:-Stylommatophora