Porifera general characters

general characters
classification

1. Phylum- PORIFERA Bollapalli Ashok Kumar M.Sc . , B.Ed ., M.A(Lit)., CSIR-NET., ( Ph.D ) LECTURER IN ZOOLOGY KRK Govt Degree & PG College ADDANKI-523201 Phone:[phone] Email: [email protected]

2. Porifera - Introduction Oldest animals which are not recognised ass animals till 18 th century Ellis (1765) identified the contractions of osculum and entry of water into these animals Linnaeus, Lamark , Cuvier included these into Zoophyta Grant(1836) gave recognition as Porifera.

3. Phylum - Porifera Basically marine, some fresh watered Biggest sponge – Spheciospongia vesparium-3.5 yards length Very small sponge- Leucosolenia blanca – 0.11 inch length Poterion patere grows 4 yards height Sponges can live at 18500 yards depth Parazoology – study of sponges.

4. Porifera - General characters Multicellular Solitary / colonial , sedentary Vase like , cylindrical , tubular, cushion shaped Radially symmetrical except few asymmetric Different coloured- grey, light brown, bright yellow, red , orange, pink/violet , black/white Diploblastic –Pinacoderm & C hoanoderm Inbetween , a gelatinous non cellular mesoderm with skeletal structures with free amoeboid cells

5. Porifera - General characters Canal system – ostia , spongeocoel , osculum Round flagellated collar cells/ choanocytes lines radial chambers and involved in collection of food, oxygen and water Skeleton is made of calcariuos or cilicious spicules or spongin fibres or both which are secreted by amoeboid cells Holozoic intracellular digestion Respiratory, excretory, locomotory appendages are absent. Respiration by simple diffusion

6. Porifera - General characters Primitive type of nervous system- bipoolar or multi polar cells formed into a network is found in some sponges Hermophradites but cross fertilisation Asexual reproduction by budding or gemmules Sexual reproduction by gametes formed from amoebocytes

7. Porifera - General characters Holoblastic cleavage Development is indirect with A mphiblastula or Parenchymula, a ciliated larva Primary germ layers of ectoderm and endoderm which are not distinguishable Regeneration is too high Sponges are seen from arctic to temperate regions

8. Porifera – Classification Classified on the basis of skeleton into three classes. They are Calcarea Hexactinellida and Demospongia

9. Class - Calcarea Small sized calcareous marine sponges Colonial or solitary. Body never exceeds 10cms height Cylindrical or vase like Skeleton- calcareous spicules; Monaxon or triaxon or tetraxon spicules No colour Canal system- ascanoid / syconoid / leuconoid type Posterior part has base andd anterior end has osculum

10. Class- Calcarea Orders : Hemocoela Heterocoela Examples : Leucosolenia , Clathrina , Schypha , Grrantia , Leucila

11. Class- HEXACTINELLIDA Cylindrical body with radial symmetry Posterior end has base, in some sponges base is provided with long spicules which are rooted into soil and thus the animal is erect Skeleton is of triaxon , six rayed , siliceous spicules Skeleton is a trabicular net. The spaces in net are lodged with syncytium. Carencyte , thesocyte , archeocyte and other amoebocyte groups form syncytium The spaces are lodged with flagellated chambers

12. Class- HEXACTINELLIDA Exopinacoderm is not clear Asexual reproduction is by budding Development is indirect with sterioblastula Benthic marine forms Orders – hexasterophora , amphidiscophora Examples- Euplectella , H yalonema , Pheronema .

13. Class -DEMOSPONGIA Small to large sized, solitary or colonial forms Skeleton is absent or silicious spicules or spongin fibres or both Silicious spicules monaxon or six rayed. Body shape is vase like, cup like or cushion like Leuconoid canal system assumed to be formed from ragon type instead of asconoid type Choanocytes restricted to small round chambers Mostly marine few fresh watered

14. Class- DEMOSPONGIA Subclasses – tetractinellida , monaxonida , keratosa Examples – Spongilla , Chalina , Chondrilla , Euspongia , Hippospongia , Cladoriza Cliona , Oscarella , Halichondria , Philospongia etc.,