Porifera
(L., porus = pore; forre = to bear)
Also called: Republic of Cells
General Characteristics
- Sponges are sessile, sedentary and marine except for Family : Spongillidae which is freshwater
- Solitary (eg. Sycon) or colonial (eg. Leucosolenia)
- Exhibit cellular level of construction without tissues (1st multicellilars)
- Acoelomate
- Asymmetrical but very few are radially symmetrical (Sycon)
- All Poriferans are filter feeders. Large number of small inhalant pores (ostia / mouthlets) and Single larger exhalant pore (osculum / anus)
- Diploblastic : outer layer ectoderm (pinacoderm) and inner layer endoderm (choanoderm)
- Choanocytes (feeding cells) or collar cells present only in Sponges
- Reproduction : Sexual (ova and sperm production) , Asexual (Budding) and Regeneration
- Fertilization is internal and cleavage is holoblastic
Phylum Porifera is divided into 3 classes (BASED ON SKELETON OR SPICULES)
Calcarea / Limy sponge | Hexactinellida | Demospongiae (largest class of sponge) |
| All marine | All marine | Marine as well as Fresh water |
| Inhabits in shallow water | Deep water | Shallow water |
| Presence of calcareous spicules (Triaxon or Tetraaxon) | Presence of silicious spicules (Triaxon or 6 rayed) | Presence of silicious spicules(Monoaxon, Tetraaxon ) or spongin fibres or both or none |
| Canal system (Ascon type / Sycon) | Leucon type canal system | Leucon type |
| Eg: Sycon, Grantia, Leucosolenia etc. | Eg: Euplectella, Hyalonema, Pheronema etc. | Eg: Spongilla, Euspongia etc. |
