Phylum Porifera

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Classification of Phylum Porifera according to Rupert & Barnes(1994)

Phylum :- Porifera

Characters :-

(i) Body perforated by number of pores,known as ostia & a large opening osculam.
                  
(ii) They possess a canal system through which water current flows transporting food & oxygen.
                  
(iii) Characteristic flagellated cells called choanocytes, lines the inner side of the body wall & are related with water circulation & feeding.
                  
(iv) Presence of an elaborate skeletal system of either calcareous or siliceous spicules or protein (collagen,spongin) fibres or combination of these.

Class :- Hexactinellida

Characters :-

(i) Skeleton of six rayed or triaxon siliceous spicules often fused into vase shaped structure.
                  
(ii) Choanocytes are restricted to finger like simple or folded chambers.
                  
(iii) The spongocoel opens by a wide osculam.



Examples :- Euplectella; Hyolonema;

Euplectella

Class :- Calcarea

Characters :-

(i) Skeleton of separate spicules made of calcium carbonate,either calcite or Aragonite.
                  
(ii) Osculam narrow & provided with oscular fringe.
                  
(iii) Entirely marine,shallow coastal water species.



Examples :- Sycon(Scypha); Leucosolenia; Grantia;

Sycon(Scypha)

Class :- Demospongia

Characters :-

(i) Skeleton composed of siliceous spicules, sponging fibres or both.
                  
(ii) Choanocytes form very small, rounded type of flagellated chambers.
                  
(iii) Mostly marine but few are freshwater.



Examples :- Spongilla(freshwater spong); Euspongia(bath spong); Clino;

Spongilla(freshwater spong)

Class :- Scelerospongia

Characters :-

(i) Marine, exhibits cryptic habits & poafer caves.
                  
(ii) Skeleton contains spicules of both silica & argonitic calcite as well as spongin.
                  
(iii) Spicules, spongin fibres & the surrounding living tissues rest on a solid basal skeleton of calcium carbonate or are enclosed within calcium carbonate chambers.



Examples :- Acanthochaetetes; Astrosclera; Stromatospongia;

Astrosclera