1. Phylum: Mollusca (continued)
Gastropods:
Meaning “stomach-footed” - a head with a flattened foot
May or may not have a shell

2. I. Shelled Gastropods (Snails)
A. Digestion: One way digestive tract (in the mouth, out the anus)
B. Circulation: Have a 1 chambered heart
C. Breathing: Breathes by taking water into its siphon tube, which brings it to internal gills

3. D. Movement in snails:
Moves along surfaces by a muscular foot
Have 2 sets of tentacles: Anterior (front) and Posterior (back):
Front pair are used for a sense of touch
Back pair are used for seeing

4. Types of Snails 1. Mud Snails:
Are scavengers – eat dead or dying organisms
Use a Radula to tear and shred dead matter

5. Mud snails on a dime

6. 2. Moon Snails Feed on live clams
Secrete a chemical out of the foot to soften the shell
Uses a radula to drill a hole in the shell
The snail inserts its mouth and eats the clam

9. 3. Cone Snails Are predatory snails
Have toxins which are used to kill prey
These toxins are of great interest to scientists and are being studied for their benefits to humans

10. Anatomy of a cone snail

12. Cone snail’s harpoon-like radula
Used to spear small fish
Then delivers poison to its prey

13. II. Shell-less Gastropods
1.The Sea Hare
A. Appearance: Have no shells or the shell is very small
B. Diet: Graze on algae
C. Protection: Some release dark ink for protection
D. Life cycle: (beginning to end) is about 1 year

14. E. Reproduction: Are Hermaphrodites – Male at the front end and female at the back end

15. Sea Hare reproduction Are Hermaphrodites
Are Male at the front end and female at the back end
They can be seen mating in large chains
They lay up to 80 million eggs in a group, and resemble spaghetti

18. California Brown Sea Hare
The largest gastropod in
the ocean
Can grow up
to 2½ feet long

19. 2. Nudibranchs or Sea Slugs
Name means “Naked Gills” (gills are easily seen on its back)
Are more than 3,000 species worldwide
Have Rhinophores (-tentacles on top of the head used for finding food and a mate)

20. Rhinphores of a nudibranch:

21. Nudibranchs (continued)
Many have finger-like structures on their back called cerata
Many are brightly colored, but a few have subtle colors for camaflouge

22. Cerata of a Komodo Dragon nudibranch:

24. Dorid Nudibranch

25. Dorid Nudibranch

26. Glossodoris Atromarginata

27. Blue Nudibranch