Phylum porifera is classified mainly basing on skeleton . It is divided into 3 classes. sponges spicules plays a very important role in classification of porifera.

1. Class: Calcarea

2. Class: Hexactinellida

3. Class: Demospongiae



1.Skeleton is made by calcareaous spicules.

2.They show single spongocoel cavity which opens to the outside through a single opening called osculum.

3.Radially symmetrical animals.

4.Choanocyte cells are large.

This is divided into 2 orders.

Order 1 : Homocoela:

1.Spongocoel is lined by choanocytes internally.

2.Simple sponges or included in this order.

Ex : Clathrina, Leucosolenia, Olynthus.


Order 2 : Heterocoela

1.Spongocoel is lined by epithelial cells.

2.Choanocytes restricted to radial canals only.

3Leuconoid or Syconoid canal system is seen. Ex : Sycon. Grantia.



1. Skeleton contains six rayed, or triaxon, siliceous spicules.

2. Radially symmetrical.

3. These are also known as glass sponges.

This class includes 2 orders

Order 1. Hexasterophora :

1. The spicules are of hexasters type.

2. They are attached to hard objects. Ex : Euplectella

Order 2. Amphidiscophora :

1. The spicules are amphidiscs.

2. These sponges are attached to the substratum by root tufts.

Ex : Hyalonema -Glass rope sponge


1.Skeleton either absent or present. The skeleton contains spongin fibres or silicious spicules or both.

This class is divided into 3 subclasses.

Subclass 1. Tetractinellida :

1.The skeleton consists of tetraxon spicules or without spicules.

2.They are mostly solid rounded structures.

3.Leuconoid canal system is present. This subclass is divided into three orders.

Order 1. Myxospongida :

1.Structure is simple

2.Skeleton is absent. Eg.Oscarella

Order 2. Carnosa (or) Homosclerophora :

1)Equal sized spicules are present.

2)Megascleres and microscleres are not sharply differentiated.

Ex : Plakina.

Order 3. Choristida :

I) Microscleres and megascleres are distinct.

Eg ,Tetilla,Geodia.

Subclass 2. Monaxonida :

1) Skeleton consists of monaxon spicules.

2)Spongin fibres may or may not be present.

3) They are cosmopolitan in their distribution.

4)Shallow or deep water forms. This subclass includes 3 orders.

Order 1. Hadromerida :

Spongin fibres absent.Monaxon spicules are represented by tylostyles.

Eg : 1) Cliona (Boring sponge) 2)Tethya.

Order 2. Halichondrida

Monaxon spicules are seen.

Eg : Halichondria.

Order 3. Poecilosclerida :

Monaxon spicules are present. Microscleres are sigmas, toxas etc.

Eg : Microciona.


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