CLAM DISSECTION CLAMS ARE Invertebrates no backbone Protostomesblastopore

CLAM DISSECTION

CLAMS ARE: Invertebrates- no backbone Protostomesblastopore becomes mouth

CLAM DISSECTION KINGDOM ANIMALIA ______ MOLLUSCA “Soft” PHYLUM ______ BIVALVIA “ 2 shells” CLASS _______ (Pelecypoda)

UMBO tells direction Anterior Posterior Dorsal Ventral

NO CEPHALIZATION (No head) Shell = valve (Bivalves = 2 shells) Growth rings Adults = sessile (stay in one place)

ADDUCTOR MUSCLES Turn POSTERIOR END toward door Cut your adductor muscles to open shell

Mantle cavity (NOT COELOM) NO cephalization Gills hang outside body in mantle cavity

Hinge Teeth on dorsal edge lock to keep shells from sliding

Smooth lining Irritants are coated by mantle to protect soft body “Pearls”

Mantle produces shell (calcium carbonate makes it hard)

INCURRENT & EXCURRENT SIPHONS move food up toward mouth CILIA on gills pull in water

SEXUAL REPRODUCTION SEPARATE SEXES Male & female clams Marine (salt water) clamsexternal fertilization Freshwater clamsinternal fertilization (sperm enters through siphon)

Other mollusks GASTROPODS- internal fertilization Land snails = hermaphrodites Aquatic snails = 2 separate sexes CEPHALOPODS- internal fertilization Separate sexes –

Indirect development TROCHOPHORE LARVA Ciliated- can swim ADULTSSessile = stay in one place Can put out foot and crawl

Trap food GILLS (PALPS move it forward) Ridges for more surface area (like typholosole) Gas exchange Diffusion moves oxygen & carbon dioxide across membrane

GAS EXCHANGE IN GILLS

ANTERIOR & POSTERIOR ADDUCTORS

FOOT – points toward anterior end

VISCERAL MASS Contains heart, digestive, excretory, reproductive

OPEN CIRCULATION • Blood flows loose inside coelom and tissue spaces • Reduced Coelom = pericardial cavity (space around heart)

PROBLEMS with OPEN CIRCULATION Less efficient way of moving oxygen & nutrients to muscles (and removing Nitrogen wastes). High oxygen and low oxygen fluids mix so muscles can’t function as efficiently

HEART & PERICARDIAL CAVITY

DIGESTIVE • Food pulled in through incurrent siphon by cilia on gills • Food trapped in mucous on gills • Palps move food up and into mouth Digestive gland esophagus stomach Intestine anus

ALL Released into Mantle cavity/ exit via excurrent siphon • Nitrogen waste from kidney • Digestive waste from anus • Sperm or egg (if external fertilization) • Larva (if internal fertilization)

NERVOUS SYSTEM http: //www. student. loretto. org/zoology/Graphic%20 webs/Clam-%20 nervous%20 system. htm 3 pairs of ganglia 2 pairs of nerve cords