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CLAM DISSECTION CLAMS ARE: Invertebrates- no backbone Protostomesblastopore becomes mouth determinate spiral cleavage CLAM DISSECTION KINGDOM ANIMALIA ___________ MOLLUSCA “Soft” PHYLUM ____________ BIVALVIA CLASS ______________ “2 shells” (Pelecypoda) UMBO tells direction Anterior Posterior Dorsal Ventral http://biog-101-104.bio.cornell.edu/BioG101_104/tutorials/animals/clam.html 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 Image from: http://sps.k12.ar.us/massengale/mollusk_notes_b1.htm Mantle cavity (NOT COELOM) Image from: http://sps.k12.ar.us/massengale/mollusk_notes_b1.htm 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” Animation from: http://vilenski.org/science/notebook/unit5/invertebrate/menu.html Mantle produces shell (calcium carbonate makes it hard) INCURRENT & EXCURRENT SIPHONS move food up toward mouth CILIA on gills pull in water Image by: Riedell/VanderWal 2005 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 ADULTS- Sessile = stay in one place Can put out foot and crawl GILLS Trap food (PALPS move it forward) Ridges for more surface area (like typholosole) Gas exchange Diffusion moves oxygen & CO across membrane GAS EXCHANGE IN GILLS H i 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 • SMALLER Coelom = pericardial cavity (space around heart) OPEN CIRCULATION is less efficient way of moving oxygen, nutrients, and nitrogen waste 1. Doesn’t go directly there 2. High oxygen and low oxygen blood can mix so it gets diluted 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 3 pairs of ganglia 2 pairs of nerve cords http://www.student.loretto.org/zoology/Graphic%20webs/Clam-%20nervous%20system.htm