CLAM DISSECTION http://www.jburroughs.org/science/resources/Clam/clam10.html

no bones around nerve cord CLAMS ARE: Invertebrates- no bones around nerve cord Protostomes- blastopore becomes mouth determinate spiral cleavage http://www.zo.utexas.edu/faculty/sjasper/images/so28_04.gif

Clam & octopus from: http://www. geocities

CLAM DISSECTION KINGDOM ___________ PHYLUM ____________ “Soft” CLASS ______________ “2 shells” ANIMALIA MOLLUSCA BIVALVIA (Pelecypoda)

UMBO tells direction Anterior Posterior Dorsal Ventral Image by Riedell/Vanderwal © 2005

Clams are SESSILE as ADULTS Don’t move much Stay in one place LARVA swim with CILIA http://seagrant.gso.uri.edu/factsheets/fsquahog.html http://www.okc.cc.ok.us/biologylabs/Images/Evolimages/trochophore.JPG

NO CEPHALIZATION (No head) Shell = valve (Bivalvia = 2 shells) Growth rings - increase with age http://wwwbio200.nsm.buffalo.edu/labs/tutor/Clam/

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

ANTERIOR & POSTERIOR ADDUCTORS

FOOT – points toward anterior end

VISCERAL MASS Contains heart, digestive, excretory, reproductive

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

Image modified from: http://www. lander

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

http://js082.k12.sd.us/My_Classes/Advanced_Biology/Ch_25/Clam%20Dissection/Clam_Dissection.htm

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 General term for reproductive organs = GONADS

SEXUAL REPRODUCTION Marine (salt water) clams- external fertilization (sperm or eggs exit through siphon) Freshwater clams- internal fertilization (sperm enters through siphon; fertilized eggs/larva exit )

Other mollusks GASTROPODS- internal fertilization Land snails = hermaphrodites Aquatic snails = 2 separate sexes CEPHALOPODS- internal fertilization Separate sexes – http://www.geocities.com/TheTropics/2428/directory.html

Indirect development ADULTS- http://www.okc.cc.ok.us/biologylabs/Images/Evolimages/trochophore.JPG 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 typhlosole) Gas exchange Diffusion moves oxygen & CO2 across membrane

GAS EXCHANGE IN GILLS Image by Riedell Diffusion moves from HIGH → LOW

OPEN CIRCULATION Blood flows loose inside coelom and tissue spaces Heart pumps blood (HEMOLYMPH) COELOM = SMALLER mainly around heart = pericardial cavity

OPEN CIRCULATION is less efficient way of moving oxygen, nutrients, and nitrogen waste Doesn’t go directly to parts  2. High oxygen and low oxygen blood can mix so it gets diluted

HEART & PERICARDIAL CAVITY

DIGESTIVE FILTER FEEDERS (strain food from water) Food pulled in through incurrent siphon by cilia moving on gills Food trapped in mucous on gills Palps move food up and into mouth esophagus  stomach Digestive gland   Intestine  anus

Makes BILE to break down fat Finishes digestion http://wwwbio200.nsm.buffalo.edu/labs/tutor/Clam/ DIGESTIVE GLAND Makes BILE to break down fat Finishes digestion

carries digestive waste to anus http://www.jburroughs.org/science/resources/Clam/clam10.html INTESTINE carries digestive waste to anus

3 Body systems use mantle cavity EXCRETORY - Nitrogen waste from kidney DIGESTIVE – feces released from anus REPRODUCTIVE- Sperm or egg (if external fertilization) Larva (if internal fertilization) Image from: http://sps.k12.ar.us/massengale/mollusk_notes_b1.htm

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