Some para on phylum proifera
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Lowest multicellular animals or metazoans without true tissues, i.e., at “Cellular level” of body organization.
- Familiar as sponges, these animals are well-known for their ability to absorb and withhold fluids.
- The word “Porifera” means pore bearers (Gr., porus = pore; ferre = to bear).
- Their body wall has numerous minute pores, called ostia, through which a continuous current of outside water is drawn into the body.
- About 5,000 species are known.
Brief History
- Robert Grant (1825) finally proved that sponges are animals, and coined the name ‘Porifera’ for these.
- Schulze (1878), Butschli (1884), Sollas (1884) and Delage (1898) separated sponges from other metazoans on basis of embryological studies, and suggested a separate group, “Parazoa” for these.
Body Organisation
Body wall consists of:
(1) Outer Dermal layer or Pinacoderm.
(a) Pinacocytes (Flat cell)
(b) Porocytes (oval)
(2) Inner Choanocytic layer or Choanoderm, Collar cell or Choanocytes (Flagellated)
(a) It is a characteristic of Porifera
(b) Choanocytes discovered by- H.J. Clark
(3) Between these two layers gelatinous material Mesenchyme is there. Consist of Amoebocytes.
(4) Body wall encloses a large cavity, the spongocoel or paragastric cavity with small cavil Choanocytes with flagella is lined in spongocoel and radial canal.
(5) Ceaselless beating of flagellate caused current of water enter through ostia perforating porocytes and various canals and enters in spongocoel and finally leave through large aperture osculum.
Canal System
Canal system of porifera help in nutrition, respiration & excretion, developed due to folding of inner wall there are four types of canal systems:
(1) Asconoid (Simplest canal) e.g. Leucosolenia, Olynthus
(2) Syconoid e.g. Scypha
(3) Leuconoid (Complex and most efficient canal system). e.g. Euspongia & spongilla
(4) Rhagon e.g. Larva of Demospongia
Skeleton
Skeleton is internal; consist of tiny calcarious calcoblast or siliceous spicules silicoblast or fine spongin fibre spongioblast, located in mesenchyme.
There are four types of spicules in sponges
(1) Monoaxon (Usually at osculum)
(2) Triaxon
(3) Tetraaxon
(4) Polyaxon
Characteristics
Scleroblast secretes spicules and spongioblast secrets spongin fibre.
Digestive cavity and mouth is absent.
Nutrition is holozoic.
Digestion is intracellular and occurs in food vacuoles of choanocytcs.
Food particle strained out by collar cell and pass them to amoebocytes.
Food is stored in thesocytes.
Distribution of food from ingestive cell to other is brought by the movable amoeboid cell.
Respiration and Excretion takes place by diffusion of gases through body surface.
Excretory matter is Ammonia.
Sponges do not have nervous system.
Reproduction takes place by means of
(A) Asexual - By Budding - Special cell mass gemmules containing archaeocytes.Endogenous budding of asexual reproduction in sponge is known as Gemmulation.
(B) Sexual - Sponges are hermaphrodite, fertilization internal and cross fertilization (Protogynous condition).
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- Familiar as sponges, these animals are well-known for their ability to absorb and withhold fluids.
- The word “Porifera” means pore bearers (Gr., porus = pore; ferre = to bear).
- Their body wall has numerous minute pores, called ostia, through which a continuous current of outside water is drawn into the body.
- About 5,000 species are known.
Brief History
- Robert Grant (1825) finally proved that sponges are animals, and coined the name ‘Porifera’ for these.
- Schulze (1878), Butschli (1884), Sollas (1884) and Delage (1898) separated sponges from other metazoans on basis of embryological studies, and suggested a separate group, “Parazoa” for these.
Body Organisation
Body wall consists of:
(1) Outer Dermal layer or Pinacoderm.
(a) Pinacocytes (Flat cell)
(b) Porocytes (oval)
(2) Inner Choanocytic layer or Choanoderm, Collar cell or Choanocytes (Flagellated)
(a) It is a characteristic of Porifera
(b) Choanocytes discovered by- H.J. Clark
(3) Between these two layers gelatinous material Mesenchyme is there. Consist of Amoebocytes.
(4) Body wall encloses a large cavity, the spongocoel or paragastric cavity with small cavil Choanocytes with flagella is lined in spongocoel and radial canal.
(5) Ceaselless beating of flagellate caused current of water enter through ostia perforating porocytes and various canals and enters in spongocoel and finally leave through large aperture osculum.
Canal System
Canal system of porifera help in nutrition, respiration & excretion, developed due to folding of inner wall there are four types of canal systems:
(1) Asconoid (Simplest canal) e.g. Leucosolenia, Olynthus
(2) Syconoid e.g. Scypha
(3) Leuconoid (Complex and most efficient canal system). e.g. Euspongia & spongilla
(4) Rhagon e.g. Larva of Demospongia
Skeleton
Skeleton is internal; consist of tiny calcarious calcoblast or siliceous spicules silicoblast or fine spongin fibre spongioblast, located in mesenchyme.
There are four types of spicules in sponges
(1) Monoaxon (Usually at osculum)
(2) Triaxon
(3) Tetraaxon
(4) Polyaxon
Characteristics
Scleroblast secretes spicules and spongioblast secrets spongin fibre.
Digestive cavity and mouth is absent.
Nutrition is holozoic.
Digestion is intracellular and occurs in food vacuoles of choanocytcs.
Food particle strained out by collar cell and pass them to amoebocytes.
Food is stored in thesocytes.
Distribution of food from ingestive cell to other is brought by the movable amoeboid cell.
Respiration and Excretion takes place by diffusion of gases through body surface.
Excretory matter is Ammonia.
Sponges do not have nervous system.
Reproduction takes place by means of
(A) Asexual - By Budding - Special cell mass gemmules containing archaeocytes.Endogenous budding of asexual reproduction in sponge is known as Gemmulation.
(B) Sexual - Sponges are hermaphrodite, fertilization internal and cross fertilization (Protogynous condition).
hope it helps
plz mark my answer as brainliest if it helps u
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