mollusca.pptx made by central university students

Geology

1. CENTRAL UNIVERSITY OF SOUTH BIHAR SUBMITTED BY AKANKSHYA PRUSTY CUSB2403512004

2. MOLLUSCA BIVALVE

3. * Found in marine and fresh water. * Shows bilateral symmetry and laterally compressed Mollusca characterized by two hinge calcareous plate (valve)enclosing the soft body. * Free swimmers like scallops ( eg . pecten) are also inequivalve.

4. Modern valves can be grouped into several morphological categories. 1.Infaunal shallow burrowing 2.Infaunal deep burrowing 3.epifaunal,attached by byssus threads to the substratum 4.Epifaunal , cemented to rock 5.Free lying 6.Swimming 7.Boring and cavity dwelling

5. The most famous swimming bivalves are the scallops, which have evolved to use jet propulsion , similar to their very distantly related cephalopod relatives .But unlike the cephalopod ,scallops evolved to use hinged shells to aid this process. 5 How does a scallop swim

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9. 10 The plane between two valve is the plane of symmetry which separates the left from right valve. In some form cardinal area is divisible into two portions. 1.Lunule-small heart shape depressed portion of cardinal area anterior to beak 2.Escuycheon-Elongated , depressed portion of cardinal area posterior to beak. Between hinge line and beak of each valve a plane or concave smooth area called hinge area or cardinal area .

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11. 12 Bivalve Shell Bivalve have an incurrent and excurrent siphon to bring in water containing food and oxygen and for excess water and waste to leave .

12. 13 Adductor muscle Monomyariana : If one adductor muscle present Dysomyarian :If there are two adductor muscle presents. Isomyarian :Both the muscle equal and identical Heteromyarian : One large and one small Depending upon position of ligament Prosodetic :Ligament present at anterior side to beak Opisthodetic :Ligament present posterior to beak.

13. 14 Dentition System

14. 15 Habitat: Benthic -Most sessile, few motile - Ifaunal -most burrow down -Epifaunal-some live on sea floor *Mussels attach with byssal threads *Scallops swim by clapping shells together .

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18. 19 Bivalve Reproduction -Separate sexes -External fertilization and development

19. 20 REFERENCES 1.Palaentology by P C Jain 2.An Introduction to Palentology by Amal Dasgupta 3.Palentology Journals 4.Internet

20. Thank you