Porifera

Subject: Biology

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Overview

Porifera includes plant like creatures with large number of minute pores. So, commonly called sponges.This note contains information about general characteristics of phylum porifera, classification and its types on the basis of spicules.
Porifera
Example of phylum Porifera
source:www.kullabs.com
fig:Example of phylum Porifera

Porifera (Gr.Porous-Pores, ferry- bearing)

  • Porifera includes plant-like creatures with a large number of minute pores. So, commonly called sponges.
  • John Ellis first recognised the sponges as an animal.
  • Robert Grant coined the term "Porifera".
  • The study of sponges or poriferans is called parazoology.

General Characteristic feature of phylum Porifera:

  • All of them are aquatic, mostly marine, rarely freshwater, solitary or colonial, sessile or redentary.
  • Body shape is vase shaped, cylindrical, spherical, cup or disc-shaped. Asymmetrical or radially symmetrical.
  • The cellular level of body organisation.
  • Diploblastic.
  • The adult body wall consists of two layers i.e. outer pinacoderm made up of a flattened cell or inner gastral choanoderm made up of complex flagellated collar cells. In between two layers, there is non-cellular mesogloea.
  • In mesogloea, there is supporting endoskeleton called spicules which are made up of CaCO3(Calcareous), SiO3(Siliceous) or protein (SpoenginRibres).
  • There is peculiar canal system whose central cavity is called paragestral cavity or sponge cell. Canal system gets in food and oxygen and carries out carbon dioxide and wastes.
  • The body surface is perforated with a large number of minute inhalant pores called Ostia and one largest exhalent pore called osculum.
  • Nutrition is holozoic and digestion is intracellular.
  • Circulation absent, respiration, and excretion through diffusion.
  • Nervous system and sense organs completely absent.
  • Bisexual reproduction asexually and sexually fusion of gametes.
  • Fertilization is internal.
  • Develop is indirect.

Classification:

Porifera consists of almost 5000 living species. They are divided into three classes on the basis of types if spicules.

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Leucosolenea
source:www.easterncapescubadiving.co.za
fig:Leucosolenea
Calcarea or calerspongia:
  • They are marine, solitary or colonial.
  • Mononon, Trianon and tetra non-type of spicules made up of CaC03.
  • Radially symmetrical.
  • A Simple canal system.
  • Eg; Sycon, Leucosolenea.
Euplectella
source:cornerofthecabinet.com
fig:Euplectella
Hyatospongiea or henantinillida:
  • They are marine found in deep sea and ocean.
  • Trianon spicules made up of Si03.
  • Radially symmetrical.
  • Branch or unbranch canal system.
  • Eg; Hyalenema, Euplectella.
Cliona
source:biogeodb.stri.si.edu
fig:Cliona
Demospongiea:
  • They are marine except spongilla. Spongilla is freshwater form.
  • Mono and Tetracon spicules made up of spongin fibre.
  • Asymmetrical
  • Complex alimentary canal.
  • Eg; Spongilla, Cliona.
Things to remember
  • Porifera includes plant like creatures with large number of minute pores. So, commonly called sponges.
  • The study of sponges or poriferans is called parazoology.
  • All of them are aquatic, mostly marine, rarely fresh water, solitary or colonial, sessile or redentary.
  • Porifera consists of almost 5000 living species.They are divided into three classes on the basis of types if spicules.
  • Body shape is vase shaped, cylindrical, spherical, cup or disc-shaped.Asymmetrical or radially symmetrical.
  • It includes every relationship which established among the people.
  • There can be more than one community in a society. Community smaller than society.
  • It is a network of social relationships which cannot see or touched.
  • common interests and common objectives are not necessary for society.

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