1. CLAM DISSECTION

2. CLAMS ARE:
Invertebrates- no backbone
Protostomes blastopore becomes mouth determinate spiral cleavage

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

5. UMBO tells direction Anterior Posterior Dorsal Ventral

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

8. ADDUCTOR MUSCLES
Turn POSTERIOR END toward door Cut your adductor muscles to open shell
Image from:

10. Mantle cavity (NOT COELOM)
Image from:
NO cephalization Gills hang OUTSIDE body in mantle cavity

11. Hinge
Teeth on dorsal edge lock to keep shells from sliding

12. Smooth lining Irritants are coated by mantle to protect soft body
“Pearls”
Animation from:

14. Mantle produces shell (calcium carbonate makes it hard)

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

16. Image by: Riedell/VanderWal 2005

17. SEXUAL REPRODUCTION SEPARATE SEXES Male & female clams
Marine (salt water) clams-
external fertilization
Freshwater clams-
internal fertilization (sperm enters through siphon)

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

19. Indirect development ADULTS- Sessile = stay in one place
TROCHOPHORE LARVA
Ciliated- can swim
ADULTS-
Sessile = stay in one place
Can put out foot and crawl

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

22. GAS EXCHANGE IN GILLS
Higher

23. ANTERIOR & POSTERIOR ADDUCTORS

24. FOOT – points toward anterior end

25. VISCERAL MASS
Contains heart, digestive, excretory, reproductive

26. OPEN CIRCULATION Blood flows loose inside coelom and tissue spaces
SMALLER Coelom = pericardial cavity
(space around heart)

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

28. HEART & PERICARDIAL CAVITY

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

31. 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)

32. NERVOUS SYSTEM 2 pairs of nerve cords 3 pairs of ganglia