general characters classification

1. Phylum- PORIFERA
Bollapalli Ashok Kumar
M.Sc. ,B.Ed., M.A(Lit)., CSIR-NET., (Ph.D)
LECTURER IN ZOOLOGY
KRK Govt Degree & PG College
ADDANKI-523201
Phone:9652929696,9441635264
Email: ashokkumarzoology@gmail.com

2. Porifera - Introduction
• Oldest animals which are not recognised ass
animals till 18th century
• Ellis (1765) identified the contractions of
osculum and entry of water into these animals
• Linnaeus, Lamark, Cuvier included these into
Zoophyta
• Grant(1836) gave recognition as Porifera.

3. Phylum - Porifera
• Basically marine, some fresh watered
• Biggest sponge – Spheciospongia vesparium-
3.5 yards length
• Very small sponge- Leucosolenia blanca – 0.11
inch length
• Poterion patere grows 4 yards height
• Sponges can live at 18500 yards depth
• Parazoology – study of sponges.

4. Porifera - General characters
• Multicellular
• Solitary / colonial , sedentary
• Vase like , cylindrical , tubular, cushion shaped
• Radially symmetrical except few asymmetric
• Different coloured- grey, light brown, bright
yellow, red , orange, pink/violet , black/white
• Diploblastic –Pinacoderm & Choanoderm
• Inbetween , a gelatinous non cellular mesoderm
with skeletal structures with free amoeboid cells

5. Porifera - General characters
• Canal system – ostia, spongeocoel, osculum
• Round flagellated collar cells/ choanocytes lines
radial chambers and involved in collection of
food, oxygen and water
• Skeleton is made of calcariuos or cilicious
spicules or spongin fibres or both which are
secreted by amoeboid cells
• Holozoic intracellular digestion
• Respiratory, excretory, locomotory appendages
are absent. Respiration by simple diffusion

6. Porifera - General characters
• Primitive type of nervous system- bipoolar or
multi polar cells formed into a network is
found in some sponges
• Hermophradites but cross fertilisation
• Asexual reproduction by budding or
gemmules
• Sexual reproduction by gametes formed from
amoebocytes

7. Porifera - General characters
• Holoblastic cleavage
• Development is indirect with Amphiblastula or
Parenchymula, a ciliated larva
• Primary germ layers of ectoderm and
endoderm which are not distinguishable
• Regeneration is too high
• Sponges are seen from arctic to temperate
regions

8. Porifera – Classification
• Classified on the basis of skeleton into three
classes. They are
1. Calcarea
2. Hexactinellida and
3. Demospongia

9. Class - Calcarea
• Small sized calcareous marine sponges
• Colonial or solitary. Body never exceeds 10cms
height
• Cylindrical or vase like
• Skeleton- calcareous spicules; Monaxon or
triaxon or tetraxon spicules
• No colour
• Canal system- ascanoid/syconoid/leuconoid type
• Posterior part has base andd anterior end has
osculum

10. Class- Calcarea
• Orders :
1. Hemocoela
2. Heterocoela
Examples : Leucosolenia, Clathrina ,Schypha ,
Grrantia , Leucila

11. Class- HEXACTINELLIDA
• Cylindrical body with radial symmetry
• Posterior end has base, in some sponges base is
provided with long spicules which are rooted
into soil and thus the animal is erect
• Skeleton is of triaxon, six rayed , siliceous spicules
• Skeleton is a trabicular net. The spaces in net are
lodged with syncytium.
• Carencyte, thesocyte, archeocyte and other
amoebocyte groups form syncytium
• The spaces are lodged with flagellated chambers

12. Class- HEXACTINELLIDA
• Exopinacoderm is not clear
• Asexual reproduction is by budding
• Development is indirect with sterioblastula
• Benthic marine forms
• Orders – hexasterophora , amphidiscophora
• Examples- Euplectella, Hyalonema,
Pheronema.

13. Class -DEMOSPONGIA
• Small to large sized, solitary or colonial forms
• Skeleton is absent or silicious spicules or spongin
fibres or both
• Silicious spicules monaxon or six rayed.
• Body shape is vase like, cup like or cushion like
• Leuconoid canal system assumed to be formed
from ragon type instead of asconoid type
• Choanocytes restricted to small round chambers
• Mostly marine few fresh watered

14. Class- DEMOSPONGIA
• Subclasses – tetractinellida, monaxonida, keratosa
• Examples – Spongilla, Chalina, Chondrilla,
Euspongia, Hippospongia, Cladoriza Cliona,
Oscarella, Halichondria, Philospongia etc.,