- Mollusca is the second largest phylum of animals, first proposed by John Ston, with over 50,000 living species that evolved 540 million years ago. They are found in both aquatic and terrestrial environments. - Molluscs have a soft unsegmented body that is usually encased in a hard calcium carbonate shell. They have a muscular foot, visceral mass containing organs, and mantle that secretes and maintains the shell. - They have well developed organ systems including a digestive system with a rasping tongue and teeth for grinding food, an excretory system with paired nephridia that collect and remove liquid wastes, and circulatory and nervous systems.

1. phylum molluca
submitted to
Maam NOOR FATIMA
submitted by
SHAHID IQBAL
Registration
2019-uam-1212
course
FRESH WATER INVERTEBRATE
MNS-UNIVERSITY OF AGRICULTURE MULTAN

2. PHYLUM MOLLUSCA
Introduction
• Mollusca
• latin words moallis means soft body
animal
• proposed by john ston
• second largest animal phylum
• Evolution of mollusca 540 years ago
• combrian period (siberia , china)
• living50,000species
• fossil species 35,000

3. Ecology of mollusca
Mollusca animal are free
living
some are sessile
Attached of surface
body(rock body)
Fresh water
Marine water
Terrestial
moist places (land snail)

4. Body characters
• shelled animal
• Body is hard, ridig(outer layer)
• shell is made of calcium carbonate
triploblastic (three layer endo ,ecto ,meso)
• coelomate cavity
• Bliteral symetery
• Unsegmented and soft body

5. Body part
• Head
• A ventral muscular foot
• Dorsal viseral mass
• Mantle present over the visral mass
• Mantle screte out shell
• Between shell and mantle contains gills

6. Digestive system
• Digrstive system consist of
gut
• two opening Mouth, Anus
• Rasping tongue like structure
• Rodula many horny teeth
• used for grinding food

7. Excretory system
• The excretory organ paired
Nephrida
• Mulluscs well developed
excretory system
• Tubular system
kidneys, that collect liquid
wastes from the coelom and
dump them in the mantle cavity,
where they are pumped out of
the shell.

8. circulatory system
• opening circulatory system
• Except (Cephalopoda) close circulatory
• coelom is divided into;
• Sinuses ,Blood space
• contain blue respiratory pigments
called Haemocynin

9. Respiratory system
• Exchange of gases into
gills
• Mantle cavity is covert into
lungs

10. Nervous system
• Nervous system consist of three pair
• interconnected ganglia
• Ganglia present in head ,foot and body regions

11. Reproductive system
• sexes separate
• protostomic characteres
• developed Trochophore larva
• spiral cleavage

12. locomotions
• organs of locomotion
muscular foot
• Movement is slow
• some are sessile

13. classification
• Mollusca six classes
 Monoplacophora
• Amphineura
• Gastropoda
• Scaphopoda
• Pelecypoda (Bivalvia)
• Cephalopoda

14. Class Gastropoda
• largest class of mullusca
• slags ,snial
• mostly marine some fresh
water,terrestial
• Asymmetrical
• prominent head and broad muscular
foot
• External shell may present or absent
• Helix asprsa ( Garden snail)
• Limax(slags)

15. class Bivalva (pepecypoda)
Bilaterally symmetrical
• Aquatic molluscs
• plate like gills
• Marine Mussel
• Oyster

16. Economic importance
• Mullusca use as man food
• button industry(mussel)
• making raods (oyster,tar)
• making Ornaments
• valuable pearls (oyster)

17. Harm full mulluscs
• mulluscs are indirectly
harmfull to man
• harmfull Mullusca
(Slags,shipworms)
• slags harmfull gardens
and other cultivations
• Teredo(shipworms)Demag

18. Refference
• Field Guide to Fresh
water invertebrate of North
America by James H.Thorp&D
• 1st year book Doctor
biology
• vedio lecture by Dr Hadi