1. MOLLUSK NOTES
Chapter 10, section 1

3. A. Characteristics of Mollusks
1. Body Structure
a. Bilateral symmetry
b. Digestive system with 2 openings

4. 2. Circulatory System
a. most have an open circulatory system

5. 3. Obtaining Oxygen
a. most have gills

6. B. Classification of Mollusks

7. Classification of Mollusks continued
usually classified by their
physical appearance such as:
a. Presence of a shell
b. Type of shell
c. Type of foot
d. Presence of a nervous system

8. Three major groups of mollusks
a. gastropods
1.) Largest group of mollusks
2.) Have a single shell or no shell at all
3.) Include snails and slugs

9. Gastropods continued…
4.) Obtaining Food
a.) herbivores animals
that eat only plants
5.) Radula – organ that flexible ribbon of tiny teeth
used like sand paper to tear throuh plant tissue

10. Mantle
Part of the mollusk that makes a shell

11. Picture of a gastropod’s radula

12. Checkpoint Gastropods use their radula to…
a. obtain food.
b. move.
c. protect themselves.
d. clean their shell.

13. ANSWER….
Obtain Food

14. Gastropods continued 6.) Movement
a.) has a muscular foot – secrets slime
1.) This helps it glide across the surface it’s moving on

15. b. Bivalves
1.) these mollusks have 2 shells held together by strong muscles
2.) Obtaining Food
a. filter feeders - capture food as water flows over their gills - food particles stick to mucus that covers the gills

16. Bivalves continued… 3.) Movement – don’t move quickly
a.) young larvae can float or swim
b.) adults stay put or use their foot to move slowly

18. Mantle – just for review
Part of the mollusk that makes the shell
It’s the soft tissue of the mollusk
In a squid it’s the outside of the squid – the part you eat if you eat calamari.

19. Bivalves continued 4.) Protection
a.) Grains of sand can get in and irritate the mantle
b.) Mantle will produce a smooth, pearly coat over the sand and and this is what makes pearls

20. Cephalopods

21. Cephalopods

22. Squid

23. Nautilus – only cephalopod with a shell

24. C. Cephalopods
1.) ocean dwelling mollusk whose foot is adapted to form tentacles around its mouth
2.) most without shells
3.) only mollusks with a closed circulatory system

25. Cephalopods continued
4.) Obtaining Food
a.) carnivores – captures prey using tentacles
1.) tentacles have suckers sensitive to taste and touch

26. Cephalopods continued
5.) Nervous System
a.) most complex nervous system of any invertebrate
b.) large eyes, good vision, large brains

27. An octopus is pretty darn smart
estimated to have 300,000,000 neurons.
An octopus has a "good" memory and can also learn.

28. Their eyes are similar to ours too…
It has a cornea, lens, iris and retina. It can also focus and form images.
It’s different from vertebrates in that it focuses light by moving the lens closer and further away from the retina. The vertebrate eye focuses by changing the shape of the lens.
Another difference is that the eye of the octopus has NO blind spot since the nerve cells leave from the outside of the eyeball.

29. Cephalopods continued
6.) Movement
a.) swim by jet propulsion
1.)) squeeze a current of water out of the mantle cavity and through a tube called a siphon

32. They are also very agile and can fit through spaces 1/10 the size of their bodies

33. Type of mollusk
How they obtain food
How they move
Gastropod:
Snails and slugs
Use radula – tongue like organ to scrape and tear plant or animal tissue
Creep along on a muscular foot leaving a slime trail

34. Clams, oysters, scallops
Type of mollusk
How they obtain food
How they move
Bivalve:
Clams, oysters, scallops
Filter Feeders
float or swim – some clap shells together to swim; muscular foot to bury themselves

35. Type of mollusk How they obtain food How they move Cephalopod: Octopus
Squid
Nautilis
Cuttlefish
Use tentacles to capture prey, crush prey in beaks, use radula to scrape and cut flesh
Swim using jet propulsion (water squirts out siphon) to propel backwards

36. The foot of a cephalopod looks like a
a. head.
b. mouth.
c. shovel.
d. tentacle.

37. Answer…
Tentacles

38. Which of the following is NOT true of ALL mollusks?
A. They have shells.
B. They have soft bodies.
C. They have a mantle.
D. They have a foot.

39. Answer
Not all mollusks have shells

40. Cephalopods move by … A. using jet propulsion.
B. moving their tentacles.
C. crawling along on a muscular foot.
D. gripping with their radula.

41. Answer
Using Jet Propulsion

42. Don’t be like this dumbo octopus

43. Use your…

44. Study for Wednesday’s quiz and don’t forget your notes!