1. Phylum Mollusca Means “soft”…refers to their bodies
Are coelemates…three body layers
with true body cavity
Two body parts:
Head-foot…travels on and has sensory organs
Visceral mass…organs
Body covered by mantle (and often a shell)
Bilateral symmetry

2. Phylum Mollusca Systems: Complete digestive system
Separate sexes, external fertilization (some hermaphrodites)
Breathe through gills
Open circulation (hemolymph)

3. Phylum Mollusca

4. Phylum Mollusca
Radula: “tongue” structure covered with “teeth” (made of chitin) scrape food.

5. Phylum Mollusca
3 Classes
Gastropoda
Bivalvia
Cephalopoda

6. Class Gastropoda “stomach-foot”… crawls on “stomach”
Snails, slugs, conch
Visceral mass turns 180o so organs exit out front (torsion)
All are motile

7. Class Gastropoda

14. Nudibrach

15. Class Bivalvia 2 halves (valves) to the shell
Clams, mussels, oysters, scallops
Most are sessile and filter feed
No head or brain, 3 pairs of ganglia
Separate sexes, external fertilization (most)

16. Class Bivalvia

25. Class Cephalopoda “head foot” travel around head first, tentacles
Octopi, squid, cuttlefish, nautilus
Most advanced nervous system of any mollusk…lobes, complex eyes
Closed circulatory system (more advanced…move faster)
Separate sexes, internal fertilization
Chromatophores (change color), ink

37. Phylum Echinodermata “spiny skin”
Sea stars, sand dollars, sea urchins, sea cucumbers
Radial symmetry (bilateral larva)
No cephalization
Ossicles (endoskelton)
Water-vascular system (not blood or hemolymph)
Tube feet (water filled … suction)

38. Tube feet

39. Class Crinoidea
e.g. crinoids, sea lillies, feather stars

42. Class Ophiuroidea
e.g. brittle stars and basket stars

45. Class Echinoidea
e.g. sea urchins, sand dollars

50. Class Holothuroidea
e.g. sea cucumber

53. Class Asteroidea “star like” Sea stars (star fish)
Oral/aboral side (mouth/not mouth)
Uses water in tubes through body for circulation (water-vascular system)
2 stomachs…one goes out of body
Nerve ring, radial nerve down each arm, eye spot (light)
Separate sexes, external fertilization

62. Phylum Arthropoda “jointed foot”
Segmented animals with appendages (“arms/legs”)
Exoskeleton for protection and support
Molt when they grow (shed exo.)
Highly cephalized…compound eye, antennae, brain
Open circulatory system (hemolymph)

63. Subphylum Crustacea
Very diverse … only 1 characteristic in common … 2 pairs of antennae
Most:
Mandible (jaws)
1 pair of appendages per segment
Segments fused together
Some breathe with gills, some through holes in exoskeleton
Indirect development (larval stage naupilus)

65. Crayfish Decapod … “10 feet” 2 body parts:
Cephalothorax (head, 5 segments, thorax)
Abdomen
Antennae (long … touch, taste)
Antennules (short … touch, taste, balance)

66. Crayfish Mandibles to chew Walking legs, pinchers, swimmerets
Maxillae and maxillipeds to manipulate food
Walking legs, pinchers, swimmerets
Complete digestive system
Gills (legs make currents)
Open circulatory system
Green gland for waste
Brain

67. Subphylum Crustacea

70. Subphylum Chelicerata and Myriapoda
Chelicerata includes spiders, scorpions, mites, horseshoe crabs, ticks
Have special mandibles called chelicera
Special lungs called book lungs
Myriapod (“many feet”)
Millipedes and centipedes

71. Subphylum Chelicerata

78. Subphylum Myriapoda

83. Class Insecta Insects…technically only 1 order (Hemiptera) are bugs
Segmented bodies (3 parts)
Head, thorax, abdomen
Exoskeleton (breathe through holes in exoskeleton)
Jointed legs (3 parts)

84. Order Hemiptera
Bugs
Damage crops, spread disease 

85. Order Hemoptera
Aphids, cicadas
Damage crops, young trees 

86. Order Isoptera Termites Damage wood in buildings 
Recycle wood in forests 

87. Order Odonata Dragonflies, damselflies Destroy harmful insects 
Nymphs are food 

89. Order Orthoptera Grasshoppers, crickets, preying mantis Damage crops 
Eats pests 

90. Order Coleoptera Weevils, beetles, ladybugs Damage crops, trees 
Eat other insects 

91. Order Diptera Mosquitoes, flies, gnats Carry disease, destroy crops 
Pollinate flowers, decompose 

93. Order Hymenoptera Bees, wasps, ants
Pollinate flowers, honey, destroy pests 
Sting 

94. Order Lepidoptera Butterflies, moths Pollinate flowers, make silk 
Larva damage crops 

97. Incomplete metamorphosis
Direct development
Young look like adult, except smaller and often without wings
Young are called nymphs.
Often several molts (shed exoskeleton) to become adult

98. Complete Metamorphosis
Indirect development
Young do not look like adult
Often involves a cocoon (chrysalis) and inside is a larva called a pupa.