1. Phylum
    2. 1. Classification of Animals
    2. Protozoa
    3. Porifera
    4. Coelenterata
    5. Platyhelminthes
    6. Nemathelminthes
    7. Annelida
    8. Earthworm
    9. Arthropoda
    10. Cockroach
    11. Mosquito
    12. Honey bee and Silk moth
    13. Mollusca
    14. Echinodermata
    15. Hemichordata
    16. Chordata
    17. Pisces
    18. Amphibia
    19. Frog
    20. Reptile
    21. Aves
    22. Mammalia
    23. Rabbit bone
  2. Animal Behaviour and Adaptation
    3. 24. Animal behaviour
    25. Animal adaptation
    26. Migration
  3. Developmental Biology
    4. 27. Development of Animals
    28. Development of Frog
  4. Human Biology
    5. 29. Tissues
    30. Sense organs
    31. Digestive system
    32. Circulatory system
    33. Respiratory system
    34. Nervous system
    35. Endocrine system
    36. Reproductive system
    37. Excretory system
    38. Skeletal system
    39. Basic concept of Immunology
    40. Human diseases
  5. Evolutionary Biology
    6. 41. Origin of Life
    42. Organic Evolution
    43. Theories of Evolution
    44. Evolution of Human beings
    45. Horse Evolution
Phylum
3. Porifera
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Image 1
Fig. Porifera
Credit. Allen
▢ Introduction:
❖ Phylum: Porifera
❖ Members: Poriferans
❖ Other names:
  1. Sponges
  2. Republic of Cells
❖ Symmetry:
◉ Most: Asymmetrical
◉ Sycon, Leucosolenia, and Larva of Sponges: Radial symmetrical
1.
❖ Grades of Organization:
◉ Cellular grade of Organization.
◉ Classification of Animal based on Tissue organization:
◈ Details:
  1. Metazoa without tissue organization are called Parazoa.
  2. Porifera belongs to group Parazoa.
◈ Study of sponges: Parazoology
1.
◉ Evolution: Sponges form the sideline of evolution.
▢ History:
❖ Robert E. Grant: Term 'Porifera' was given by Robert E. Grant.
❖ John Ellis:
  1. Animal nature of Sponge was discovered by John Ellis.
  2. Sponges appear to be quite lifeless and plant-like.
❖ H.W. Wilson: Regeneration in Sponge was discovered by H.W. Wilson.
Note
John Ray
John Ray gave the term 'Species.'
John Hill
John Hill gave the term 'Paramecium.'
Johnston
  1. Johnston gave the term 'Mollusca' (Mollusca means soft body).
  2. Johnston's organ is Proprioreceptor (Receptor of Sound 🔊 vibration and CO2) in mosquito.
Jacobson's organ
  1. Also called Vomeronasal organ (VNO), an organ of chemoreceptor that is part of the olfactory system of amphibians, reptiles, and mammals.
  2. Function: Smell
1.
2.
▢ Classification:
❖ Based on Skeleton/ Spicules:
Type
Calcarea/ Limy Sponge
Hexactenellida
Demospongia
Spicules
Calcareous spicules (Triaxon or Tetraxon or None)
Silicious spicules (Triaxon with 6 rays or Both)
Siliceous spicules (Calcareous spicules)
Habitat
All marine, never found in cold water
All marine
Most marine, Few freshwater
Habit
Sessile, sedentary, and fixed
Canal
System/
Aquiferous
System
Ascon or Sycon or Leucon
Leucon
Leucon
Examples
▢ Sycon/ Scypha:
Image 1
Fig. Sycon
  • •
    Urn sponge or Crown sponge
▢ Leucosolenia:
Image 1
Fig. Leucosolenia
  • •
    Smallest sponge
▢ Grantia:
Image 1
Fig. Grantia
▢ Clathrina:
Image 1
Fig. Clathrina
▢ Euplectella:
Image 1
Fig. Euplectella
  • •
    Venus flower basket
▢ Hyalonema:
Image 1
Fig. Hyalonema
  • •
    Glass rope spone
▢ Cliona:
Image 1
Fig. Cliona
  • •
    Boring sponge
  • •
    Sulphur sponge
▢ Pheronema:
Image 1
Fig. Pheronema
  • •
    Bowl sponge
▢ Spongilla:
Image 1
Fig. Spongilla
  • •
    Fresh water sponge
▢ Euspongia:
Image 1
Fig. Euspongia
  • •
    Bath 🛀 sponge
▢ Chalina:
Image 1
Fig. Chalina
  • •
    Mermaid's gloves
▢ Hippspongia:
Image 1
Fig. Hippspongia
  • •
    Horse 🐎 sponge
1.
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3.
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5.
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❖ Non-Sponge:
  1. Spongicola – Spongicola is Shrimps of Arthopoda. It has got the name Spongicola as it lives in Euplectela sponge as Commensalism(+, 0).
1.
▢ Body Pores:
Image 1
S.N.
Ostia
Osculum
i.
Ostia act as mouth of Sponge.
Osculum acts as Anus of Sponge.
ii.
Ostia are many in number.
Osculum is single in number.
iii.
Ostia are without oscular fringes.
Osculum is provided with Oscular fringes/ Valvular fringe.
iv.
Ostia is Non-valvular.
Osculum is Valvular.
v.
Ostia is also called Incurrent pore.
Osculum is also called Excurrent pore.
vi.
Opening and Closing controlled by Myocytes.
Osculum opening is mainly controlled by Myocytes.
1.
▢ Body Walls and Cells:
Image 1
Fig. Sponge Body wall and Cells
❖ Diploblastic Animals:
◉ Outer layer/ Pinacoderm/ Dermal epithelium:
  1. Pinacocyte: Binucleated/ Coenocytic/ Multinucleated
  2. Porocyte
◉ Mesenchyme or Mesohyl:
  1. Jelly-like substance found between the two layers called Mesenchyme or Mesohyl.
  2. Consists of Skeletal elements (Spicules), Collagen fibres, and Free Amoebocytes/ Wandering cells.
◉ Amoebocyte Cells:
S.N.
Amoebocyte cells
Features
1)
Archaeocytes
  1. Largest amoebocytes
  2. Can be converted into any other types of amoebocyte (totipotent cell)
  3. Helps in regeneration called morphallaxis
  4. Reproductive cells are also produced from archaeocytes
  5. Helps in formation of internal bud called gemmule for asexual reproduction
2)
Thesocytes
Stores food in the form of Glycogen granules.
3)
Trophocytes
Provide food to developing cells (Nurse cells or Nutritive cells).
4)
Scleroblast
  1. Multinucleated
  2. Calcoblast = CaCO₃ (secretes the spicules)
  3. Silicoblast = Silica
  4. Spongioblasts = Spongin fibres
5)
Collencyte/ Connecting cells
Secretes Collagen fibres.
6)
Myocytes/ Contractile cells
  1. Present at ostia and osculum (but mainly at osculum).
  2. Helps in closing and opening of Osculum.
7)
Chromocytes/ Pigment cells
Gives color as well as excretory in nature.
8)
Phagocytes
Phagocytic in nature (engulf foreign particles).
9)
Germ cells
Reproduction.
10)
Gland cells
Serve for attachment by secreting slimy substance (mucus).
❖ Inner layer/ Choanoderm/ Gastral epithelium:
  1. Choanocyte/ Collar cells/ Flagellated cells
  2. Choanocytes or Collar cells are only present in Sponges.
  3. Water current through the body of sponge is maintained by Choanocytes.
  4. Choanocytes help in Nutrition by ingesting food through the incoming water (holozoically).
  5. The cavity common to all sponges is Spongocoel or Paragastric cavity lined with flagellated choanocytes.
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8.
▢ Water Canal System/ Aquiferous System:
❖ Description:
  1. Sponges have a canal system also known as Water Canal System or Aquiferous system.
  2. Canal system is a characteristic feature of Sponges.
  3. Sponges need a continuous current of water flowing through their bodies for Nutrition, Respiration, Excretion, and Reproduction.
❖ Types:
1. Ascon type
2. Sycon type
3. Leucon type
4. Rhagon type
Image 1
Image 1
Image 1
Flow of Water
graph TD 1["Water"] 2["Ostia"] 3["Spongiocoel"] 4["Osculum"] 5["Out"] 1 --> 2 2 --> 3 3 --> 4 4 --> 5
graph TD 1["Water"] 2["Ostia"] 3["Incurrent carnal"] 4["Prosopyle"] 5["Radial canal"] 6["Apopyle"] 7["Osculum"] 8["Out"] 1 --> 2 2 --> 3 3 --> 4 4 --> 5 5 --> 6 6 --> 7 7 --> 8
graph TD 1["Water"] 2["Ostia"] 3["Incurrent carnal"] 4["Prosopyle"] 5["Radial canal"] 6["Apopyle"] 7["Excurrent canal"] 8["Osculum"] 9["Out"] 1 --> 2 2 --> 3 3 --> 4 4 --> 5 5 --> 6 6 --> 7 7 --> 8 8 --> 9

Transformed to Leucon type during adulthood.

Notes
1. Incurrent canal is lined by Pinacocytes. 2. Prosopyle is lined by Porocyte. 3. Radial canals are lined by Choanocytes.
Examples
Leucosolenia
Sycon
Spongilla
Some
larval
stages
1.
2.
3.
4.
▢ Regeneration Capacity:
❖ Types:
Epimorphosis
Morpholaxis
Character
Regeneration of lost part.
Each cut piece grows into a new organism.
Examples
  1. Sponges
  2. Starfish
  1. Porifera
  2. Coelenterata
❖ General: All Porifera without exception show high power of Regeneration.
❖ Reasons: Due to archaeocytes which are highly totipotent cells.
1.
▢ Metabolism:
❖ Digestion:
◉ Nutrition:
◈ General: All sponges are filter feeders.
◈ Other filter feeders:
  1. Ciliates
  2. Sponges
  3. Mollusca ⟶ Bivalvia e.g., Unio
  4. Hemichordata
  5. Protochordata
◉ Intracellular and holozoic. Takes place partially in choanocytes and partially in wandering amoebocytes. Digestion of food takes place in Food vacuoles.
❖ Respiration: Performed by both Choanoderm and Body surface, but mainly by Choanoderm.
❖ Circulation: Takes place by Wandering of Amoebocyte cells.
❖ Excretion and Gas Exchange: Primarily Ammonia; Simple diffusion occurs across the Choanoderm.
▢ Reproduction:
❖ General: Porifera reproduces by both Asexual and Sexual methods.
❖ Asexual Reproduction:
Internal Bud (Gemmule)
External Bud
Characters
  1. Formed by the aggregation of Archaeocytes.
  2. Gemmulation is the process of forming internal bud.
  3. Formed during unfavorable conditions.
Formed during favorable conditions.
Examples
Spongilla
  1. Sycon
  2. Leucosolenia
❖ Sexual Reproduction:
graph TD 1["Sperm"] 2["Ova"] 3["Zygote"] 4["Larva (Motile)"] 5["Adult (Sessile)"] 1 --> 3 2 --> 3 3 --> 4 4 --> 5
◉
  1. Porifera are Bisexual/Monoecious (⚤) and Protogynous (Female gametes mature first).
  2. Cross-fertilization is the rule.
  3. Cleavage of zygote is Holoblastic (Complete division) and Equal.
  4. Larva is active and floating but adult is sedentary and sessile.
◉ Larval Stages:
Larva
Description
Comparable To
Amphiblastula
Larva of Sycon
N/A
Parenchymula
Larva of Leucosolenia
Planula of Obelia (Motile)
Stero-gastrula
Larva of Euplectela
N/A
1.
2.
◉ Olynthus:
  1. Short-lived stages formed when the colony becomes attached to a Substrate.
  2. Hypothetical ancestral stage of Sponge.
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Multiple Choice Questions

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[MOE 2063]

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[MOE 2062]

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[MOE 2052]

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[IOM 2007]

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[IOM 2006]

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[IOM 2002]

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[BPKIHS 2006]

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[BPKIHS 2007]

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[IE 2003]

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[IOM-2015]

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[MOE 2012]

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[KU 2012]

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