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Porifera general characters
This document provides information about the phylum Porifera (sponges). It discusses their general characteristics such as being multicellular, solitary or colonial, having a canal system for water flow, and having skeletons made of silica spicules or spongin fibers. The phylum contains three classes - Calcarea, Hexactinellida, and Demospongia - which are classified based on their skeletal structures and compositions. Examples of orders and genera within each class are also provided.
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Porifera general characters
- 1. Phylum- PORIFERA Bollapalli AshokKumar M.Sc. ,B.Ed., M.A(Lit)., CSIR-NET., (Ph.D) LECTURER IN ZOOLOGY KRK Govt Degree & PG College ADDANKI-523201 Phone:9652929696,9441635264 Email: ashokkumarzoology@gmail.com
- 2. Porifera - Introduction •Oldest animals which are not recognised ass animals till 18th 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 - Generalcharacters • 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 & Choanoderm • Inbetween , a gelatinous non cellular mesoderm with skeletal structures with free amoeboid cells
- 5. Porifera - Generalcharacters • 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 - Generalcharacters • 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 - Generalcharacters • Holoblastic cleavage • Development is indirect with Amphiblastula 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 1. Calcarea 2. Hexactinellida and 3. 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: 1. Hemocoela 2. Heterocoela Examples : Leucosolenia, Clathrina ,Schypha , Grrantia , Leucila
- 11. Class- HEXACTINELLIDA • Cylindricalbody 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 • Exopinacodermis not clear • Asexual reproduction is by budding • Development is indirect with sterioblastula • Benthic marine forms • Orders – hexasterophora , amphidiscophora • Examples- Euplectella, Hyalonema, Pheronema.
- 13. Class -DEMOSPONGIA • Smallto 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.,