Phylum :Porifera

Characteristics Predominantly marine except for two fresh – water families. Metazoan, with loosely aggregated cells. Adults sessile, commonly encrusting. A symmetrical or radially symmetrical. Body permeated with pores, canals and chambers through which a water current flows. Internal cavities are , at least partially , lined with flagellated cells (choanocytes). Possess an internal skeleton of spicules and / or organic fibers. They have some form of internal cavity (spongocoel) that opens to the outside by as osculum. There are no organs , no systems , no mouth or digestive tract , a nervous system is absent.

Characteristics There are no special organs for reproduction , sponges can reproduce asexually by budding , the formation of reproduction bodies , and by formation of gemmules. Sexual reproduction by produce ova and sperm at different times to ensure cross-fertilization. Most sponges are hermophrodites. Possess high regenerative powers.

Sponges divided according to it’s body form to three types. Asconoid type Syconoid type Leuconoid type

Class : Calcarea Sponges with spicules of calcium carbonate, needle shaped or three – rayed or four – rayed ; canal system asconoid , syconoid , or leuconoid ; all marine.

Order : Homocoela (Sponges with simplest body form (asconoid type)) e Order : Homocoela (Sponges with simplest body form (asconoid type)) e.g. : Leucosolenia Leucosolenia The asconoid canal system is best seen in this animal , which grows in a cluster , or colony , of tubular individuals in varying stages of growth large individuals may carry one or more buds. The body wall is covered with pinacocytes on the outside and filled with mesophyl that contains amebocytes and spicules. Incurrent pores extend from the external surface directly to the spongocoel , which is lined with flagellated choanocytes. The choanocytes produce the water current and collect food. An osculum serves as the excurrent outlet of the spongocoel.

Order : Hetercoela (Sponges belongs this order have syconoid and leuconoid body form e.g. : Grantia Grantia is a syconoid type of sponge. In general it is vase shaped , with a body wall mad up of a system of tiny , interconnected dead – end canals whose flagellated cells draw in water from the outside through minute pores , take from it the necessary food particles and oxygen, and then empty it into a large central cavity (spongocoel) for exit to the outside. The body wall seems to be made up of innumerable bristly , fingerlike processes pointing outward. Inside each of these processes is a radial canal , which is closed at the outer end but which opens into a central cavity called the spongocoel (Paragaster). The external spaces between these enclosed canal are incurrent canals , which open to the outside but end blindly at the inner end. Grantia

Order : Hetercoela (Sponges belongs this order have syconoid and leuconoid body form e.g. : Grantia The outside openings , or pores , are called dermal ostia. Water enters the incurrent canals and passes through minute openings called prosopyles into the radial canals and then to the spongocoel through the apopyles and out through the osculum. There is no mouth , anus , or digestive system. Grantia spicule

Class : Hexactinellida Sponges with three – dimensional , six – rayed siliceous spicules , spicules often united to form network ; body often cylindrical or funnel shaped ; canal system syconoid or leuconoid ; all marine, mostly deep water. e. g. Euplectella

Class : Demospongia Sponges with siliceous spicules , or spongin or both ; canal systems leuconoid ; one family fresh water. All other marine

Order : Monaxonida (Sponge with needle shaped spicules) e. g Order : Monaxonida (Sponge with needle shaped spicules) e.g. : Chalina ; Spongilla ; Ephydatia The fresh water sponges and some marine demospongiae reproduce a sexually by means of gemmules , made up of clusters of amebocytes. Gemmules of the freshwater sponges are enclosed in hard shells and can withstand adverse conditions that would kill the adult sponges. In the spring they develop into young sponges. Marine gemmules give rise to flagellated lrvae. Spongilla spicule Ephydatia gemmule

Order : Keratosa (contain commercial sponges , skeleton of spongin fibers) e.g. : Euspongia