Phylum PORIFERA : General Characteristics and Classification


(L., porus = pore; forre = to bear)

Also called: Republic of Cells

General Characteristics

  1. Sponges are sessile, sedentary and marine except for Family : Spongillidae which is freshwater
  2. Solitary (eg. Sycon) or colonial (eg. Leucosolenia)
  3. Exhibit cellular level of construction without tissues (1st multicellilars)
  4. Acoelomate
  5. Asymmetrical but very few are radially symmetrical (Sycon)
  6. All Poriferans are filter feeders. Large number of small inhalant pores (ostia / mouthlets) and Single larger exhalant pore (osculum / anus)
  7. Diploblastic : outer layer ectoderm (pinacoderm) and inner layer endoderm (choanoderm)
  8. Choanocytes (feeding cells) or collar cells present only in Sponges
  9. Reproduction : Sexual (ova and sperm production) , Asexual (Budding) and Regeneration
  10. Fertilization is internal and cleavage is holoblastic

Phylum Porifera is divided into 3 classes (BASED ON SKELETON OR SPICULES)

Calcarea / Limy sponge
Demospongiae (largest class of sponge)
All marineAll marineMarine as well as Fresh water
Inhabits in shallow waterDeep waterShallow 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 systemLeucon type
Eg: Sycon, Grantia, Leucosolenia etc.Eg: Euplectella, Hyalonema, Pheronema etc.Eg: Spongilla, Euspongia etc.

Binod G C

I'm Binod G C (MSc), a PhD candidate in cell and molecular biology who works as a biology educator and enjoys scientific blogging. My proclivity for blogging is intended to make notes and study materials more accessible to students.

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