1. MOLLUSKS AND SEGMENTED WORMS
CHAPTER 35
MOLLUSKS AND SEGMENTED WORMS

2. MOLLUSKS-SOFT BODIED Three distinct parts:
Visceral mass-houses the organs
Muscular foot aids movement and secretes mucus (that’s the trail of slime snails leave behind)
Mantle secretes the shell

3. DIGESTIVE SYSTEM REPRODUCTION NERVOUS SYSTEM
Radula-tongue-like organ with rows of teeth used to scrape or cut food
Bivalves are filter feeders. Gills used to filter food from water
REPRODUCTION
Most have separate sexes for external fertilization; land dwellers are hermaphrodites
NERVOUS SYSTEM
Brain and nerves that control movement and behavior
Some have simple eyes that detect light; others have compound eyes that function as well as those in humans.

4. CIRCULATORY SYSTEM RESPIRATORY SYSTEM EXCRETORY SYSTEM-
Three chambered heart
Most have an Open circulatory system; there are no blood vessels that transport blood back to the heart.
RESPIRATORY SYSTEM
Aquatic mollusks have gills for gas exchange
Land mollusks have lungs
EXCRETORY SYSTEM-
Wastes are removed from the body by nephridia

6. Classes of mollusks GASTROPODS-stomach-footed
one shelled -snails, conch, periwinkle
No shell-slugs; they are protected by mucus
May be herbivores, predators, or parasites

8. BIVALVES-two shelled mollusks
Clams, oysters, scallops
No distinct head or radula
Use muscular foot to burrow in sand
ligament-hinge-like structure that connects the shells
Filter feeders

9. CEPHALOPODS-head-footed
Octopus, squid, chambered nautilus
Foot has evolved into tentacles with suckers, hooks, and adhesive structures
Jet propulsion to move and escape predators

11. SEGMENTED WORMS-ANNELIDS (“Little Rings”)
Body plan resembles a tube within a tube.
inner tube forms the digestive tract
Bristles or setae on each segment which anchor worms into the soil
Ringed segments are separated; have separate muscles, separate functions,

12. Closed circulatory system
Simple nervous system
Brain in some species attached to ganglia in each segment by nerve cord
Closed circulatory system
Carry blood throughout the body in vessels
Can also breathe through their skin
Complete digestive tract-includes mouth, pharynx, esophagus, crop, gizzard, intestines, and anus
Reproductive system
Earthworms and leeches are hermaphrodites
Sperm is exchanged and fertilization takes place in a capsule which is shed and left behind in soil to hatch

14. CLASSES OF ANNELIDS OLIGOCHAETA POLYCHAETA HIRUNDINEA EARTHWORMS
100+ SEGMENTS
CALLED FARMER’S HELPER
CASTINGS (WORM POOP) ADDS NUTRIENTS TO THE SOIL
POLYCHAETA
BRISTLEWORMS, SANDWORMS
HIRUNDINEA
LEECHES
PARASITIC; HAVE SUCKERS ON EACH END WITH ALLOW THEM TO ATTACH TO A HOST FOR FEEDING
ONCE USED FOR MEDICINAL PURPOSES

15. EARTHWORM DISSECTION