Dissection of the Clam copyright cmassengale 1 Taxonomy

Taxonomy of Bivalve Mollusks Kingdom Phylum Class Genus Species • • • Animalia Mollusca

Bivalve Mollusks • Soft bodies invertebrates • Have a Hatched foot that can be

Bivalve Mollusks • No eyes or distinct head • Have siphons to circulate water

Bivalve Mollusks • Have a fully lined body or mantle cavity • Body organs

External Anatomy copyright cmassengale 6

Bivalve Shell • The hinge ligament holds the two halves of the shell together

Bivalve Shell • Umbo is the raised, oldest part of the shell and is

Bivalve Shell • Shell show regular spacing of external growth rings on shells and

Bivalve Shell • Bivalves have an incurrent and excurrent siphon to bring in water

Internal Anatomy copyright cmassengale 12

Scissor tips or a screwdriver & can be used to open the shell copyright

Adductor Muscles Strong adductor muscles help open & close the valves and must be

Inside Shell Lining • The inside of the shell is pearly and smooth to

Teeth located on the dorsal edge of the shell lock to keep shells from

The mantle makes a Ca. CO 3 (limestone) shell copyright cmassengale 18

Water Flow • Incurrent siphons aid in bringing in water with food and oxygen

Heart and pericardial cavity copyright cmassengale 24

Nervous System • Consists of 3 pairs of ganglia (brain) • Has 2 pairs

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Dissection of the Clam copyright cmassengale 1

Taxonomy of Bivalve Mollusks Kingdom Phylum Class Genus Species • • • Animalia Mollusca Bivalvia Venus mercenaria copyright cmassengale 2

Bivalve Mollusks • Soft bodies invertebrates • Have a Hatched foot that can be extended for movement • Two part, hinged shell • Complete, one-way digestive tract with a mouth & anus • Separate sexes copyright cmassengale 3

Bivalve Mollusks • No eyes or distinct head • Have siphons to circulate water through their bodies • Filter feed on plankton • Mussels are large and have a flat, more oblong shell shape, while freshwater clams are smaller (3/4 inch) and typically more round copyright cmassengale 4

Bivalve Mollusks • Have a fully lined body or mantle cavity • Body organs called visceral mass protected by mantle which secretes the shell • Open circulation • Most are sessile or sedentary • Includes clams, oysters, scallops, & mussels copyright cmassengale 5

External Anatomy copyright cmassengale 6

Bivalve Shell • The hinge ligament holds the two halves of the shell together copyright cmassengale 7

Bivalve Shell • Umbo is the raised, oldest part of the shell and is used to find surfaces Dorsal UMBO Posterior Anterior Ventral copyright cmassengale 8

Bivalve Shell • Shell show regular spacing of external growth rings on shells and their progressive crowding as the animals grow older Growth Rings copyright cmassengale 9

Bivalve Shell • Bivalves have an incurrent and excurrent siphon to bring in water containing food & O 2 and for excess water & wastes to leave Siphons copyright cmassengale 10

Internal Anatomy copyright cmassengale 12

Scissor tips or a screwdriver & can be used to open the shell copyright cmassengale 13

Adductor Muscles Strong adductor muscles help open & close the valves and must be cut to examine the interior of the clam copyright cmassengale 14

Inside Shell Lining • The inside of the shell is pearly and smooth to protect the body • Oysters coat irritants with a substance called “mother of pearl” copyright cmassengale 16

Teeth located on the dorsal edge of the shell lock to keep shells from sliding copyright cmassengale 17

The mantle makes a Ca. CO 3 (limestone) shell copyright cmassengale 18

Water Flow • Incurrent siphons aid in bringing in water with food and oxygen • Cilia direct water into the gills, while labial palps direct water into the mouth move food toward the mouth Cilia on the gills pulls in water copyright cmassengale 23

Heart and pericardial cavity copyright cmassengale 24

Nervous System • Consists of 3 pairs of ganglia (brain) • Has 2 pairs of nerve cords extending from this copyright cmassengale 26