1. Mollusks Soft-bodied invertebrates that normally have shells.
Mollusks are classified according to their foot, whether or not they have a shell, and the type of shell they have.
Mollusks are useful as a food source (clams, oysters, scallops).
We also make jewelry (pearls) from mollusks.
Have a body cavity for organs

2. Gastropods Single-shell (some don’t have a shell)
Use a RADULA to eat with (tongue that works like a rough file).
Includes slugs and snails
This Photo by Unknown Author is licensed under CC BY-SA

3. Bivalves
Two part shell
Includes clams, scallops, and oysters.

4. Cephalopod No shell (usually). Includes squid, octopus, and nautilus
They have the most specialized members

5. Segmented Worms (annelids)
Use a GIZZARD to grind soil for food.
Store food temporarily in a CROP
Have a body cavity for organs.
Bilateral symmetry
Bristle-like setae help them move.
Closed circulatory system. (has blood in blood vessels, unlike an open circulatory system.
Larva look like spinning tops with cilia, much like mollusks, so they probably have a common ancestor

6. Arthropods Invertebrates with jointed appendages.
Exoskeleton (hard outer covering)
Exoskeleton gets outgrown so they shed it through molting.
Keeps body from drying out.
Usually lightweight.
Supports and protects the body.
Appendages: Antennae, legs, arms, claws, and pincers.
Body cavity, nervous system, mouth and anus.
Insects, arachnids, millipedes, centipedes, and crustaceans

7. Metamorphosis Change animals go through to become adults. Complete
egg, larva (grub, caterpillar, maggot, etc.), pupa, adult
Incomplete
Egg, nymph (mini-adult), adult

8. Insects Largest group of complex invertebrates.
Includes things like grasshoppers.

9. Spiders and ticks
8 legs
2 body segments
Arachnids

10. Echinoderms Spiny skinned invertebrates
Move with tube feet (like suction cups)
Radial symmetry
Internal skeleton
Water – vascular system
Opens shells with tube feet, inverts stomach onto the prey, enzymes dissolve the prey, sucks stomach and food back in.