Biology

Phylum Porifera

Phylum Porifera

Word Porifera is derived from a Greek word (Poros-pore, ferre-to bear)

Porifera includes stagnant water animals, commonly known as Sponges.

There are three types of sponges:

  • Asconoid
  • Syconoid
  • Leuconoid

About 5,000 species of sponges are known in the phylum Porifera.

They are distinct from protozoans in having a cellular grade of structural organization.

They are mostly marine forms and remain attached to rocks.

They are sessile, colonial.

Their body has no organs.

They are multicellular.

They are acoelomate organisms.

They possess a cellular level of body organization.

Their body is vase-shaped, cylindrical, or cushion-shaped.

They are asymmetric or with radial symmetry.

The body wall is diploblastic with an outer dermal (ectodermal) and an inner gastral (endodermal).

Water enters through minute pores called Ostia.

One or more large pores are located in Ostia called the osculum.

They possess a peculiar canal system through which water current flows which carry food and oxygen.

Water transport is helpful in gathering food, respiration, and excretion.

A layer of peculiar collared cells is called Choanocytes.

Choanocytes lines spongocoel.

 

They exhibit holozoic nutrition.

Digestion is intracellular.

Respiratory, Circulatory, and respiratory system is absent.

Internal fertilization.

Sexes are not separate (Hermaphrodite) but reproduction takes place:

Asexual Reproduction: Budding, Fission, or gemmule formation.

Sexual Reproduction: Gametogamy.

Possess a high capability for regeneration.

The body is supported by a skeletal of spicules or spongin fibers.

Examples: Sycon (Scypha), Euplectella (Venus flower basket), Hyalonema (glass-rope sponge), Euspongia (Bath sponge), Cliona (boring sponge), Spongilla (freshwater sponge), Leucosolenia, Chalina (mermaid’s gloves), etc.

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