1. Arthropods Characteristics

2. Arthropods-Insects Makes up ¾’s of all animals species
Includes insects, spiders, scorpions, millipedes, centipedes, crabs, lobsters & crayfish
Anthropod means “jointed foot/leg”
Jointed appendages (legs, antenna, mouth parts)
Segmented body with paired appendages on each segment

3. Arthropods
Millipedes & Centipedes

5. Arthropods-Spiders
6. External exoskeleton made of chitin (carbohydrate) & protein for protection & support
7. Exoskeleton has 3 layers- outer waxy layer repels water, middle layer has calcium for extra strength & inner layer has flexible joints for movement
8. Deuterostomes
9. Coelomate
10. Ventral nervous system

6. Arthropods-Crabs & Barnacles

7. Arthropods-Scorpions
11. Open circulatory system
12. Specialized sensory receptors & high degree of cephalization
13. Have simple or compound eyes & segmented antenna

8. Arthropods-Lobsters & Crayfish

9. Arthropods Movement & growth

10. Arthropods-Horseshoe crabs
1. Muscles occur in bundles & are attached to inside of exoskeleton on each side of joints

11. Arthropod-Growth
2. Exoskeleton must be periodically molted (shed) for organism to grow
3. Molting called ecdysis
4. Molting hormone released & causes epidermal cells to secrete enzymes that digest & loosen inner exoskeleton
5. New exoskeleton secreted by epidermal cells flexible at first & must harden so arthropod not vulnerable to predators so often stay in hiding after molting
6. Arthropods go through numerous molts

12. Arthropods Evolution & Taxonomy

13. Arthropods Four subphyla Trilobita- extinct trilobites
Crustacea- shrimps, lobsters, crayfish & barnacles
Chelicerata- spiders, scorpions & ticks
Uniramia- centipedes, millipedes & insects

14. Arthropods Subphyla trilobita Includes extinct trilobite Marine
Have a head & segmented trunk with one pair of legs one each segment
Breathe through gills
Single pair of antenna

15. Subphylum Chelicerata
 Characteristics
1.Includes 2 classes- Xiphosura (horseshoe crab) and Arachnida (spiders, ticks, scorpions & mites)
2. Have a cephalothorax (fused head & thorax) and abdomen

16. Subphylum Chelicerata
 Characteristics
8. Ticks & Mites
a. Parasitic arachnid
b. Need blood meal to molt
c. Ticks carry Lyme disease & Rocky Mountain Spotted Fever
9. Scorpions
a. Prefer dry regions
b. Breath through book lungs
c. Nocturnal predators

17. Subphylum Crustacea Characteristics
1.Marine members include shrimp, lobster, copepods,
barnacles & crabs
2. Terrestrial crustaceans called isopods includes
pillbugs & sowbugs
3. Freshwater members include crayfish &
Daphnia (water fleas)
4. All have jaws or mandibles for chewing or tearing
5. have 10 pairs of jointed appendages
6. Breathe through gills
7. Barnacles
a. Marine
b. Sessile crustaceans that live in limestone case
c. Filter plankton with 12 appendages called cirri
8. Isopods (pillbugs & sowbugs)
a. Some live on land in dark places

18. Subphylum Crustacea
9. Crayfish
a. Antennules located on head help balance, touch & taste
b. Statocysts- balancing organs at the base of antennules
c. Maxille- paired mouthparts that move side to side to tear food
d. Maxillipeds- help hold food
e. Swimmerets- under abdomen to swim, gas exchange, & protect eggs/ young
f. Abdomen ends in flat segment called telson with flat uropods on each side
g. Chitinous teeth in stomach grind food
h. Open circulatory system with heart to pump blood to gills & body cells
i. Gills attached to walking legs

19. Subphylum Crustacea Copepods a. Largest group of crustaceans
b. Make up most of the marine plankton
c. Serve as food for many marine
animals
d. Found in freshwater, marine & moist
terrestrial environments

20. Subphylum Uniramia Characterists Class Chilopoda Class Diplopoda
1.Includes 3 classes- Chilopoda (centipedes), Diplopoda (millipedes) & Insecta
2. Most are terrestrial
3. Exoskeleton prevents desiccation (water loss)
Class Chilopoda
1.Terrestrail centipedes – VS (not)
2. Have 1 pair of legs per body segment
Class Diplopoda
1.Terrestrial millipedes
2. Roll into balls when threatened & spray noxious chemical containing cyanide

21. Stop!

22. The head and thorax are covered by a common “shell,” or covering termed the “carapace.”
The front end of the carapace has “the rostrum,” a spike-like projection from the front end.
The eyes are on stalks and there are two sets of sensory appendages termed antennae.
Each of the first pair of antennae has two branches.
Each of the second pair of antennae has one long branch and a smaller scale-like branch at the base.
The primitive forms have eight thoracic segments.

24. Each thoracic segment bears an appendage that may be used for walking.
Each thoracic appendage may bear a gill found up under and protected by the carapace.
The abdomen projects beyond the carapace and has six segments.
The first five abdominal segments have flap-like swimming appendages found underneath it.
The last abdominal segment bears a pair of lateral flaps and is typically flattened.  Together with the lateral flaps, it is often called the tail fan.

25. True Crabs Crabs are flattened from top to bottom.
The first pair of remaining thoracic appendages ends in large pinching claws.
The last four pairs of thoracic appendages are walking legs.
The first abdominal segment is small.
The abdominal appendages are small and modified, and not used for swimming.
The abdomen is curved under the thorax where it fits in a groove on the animal's underside.
True Crabs

26. Arthropods of the PNW

27. Barnacles

28. Barnacles
Acorn barnacle
White acorn barnacle
Leaf barnacle

29. True Crabs
Dungeness crab
(Shield-backed) Kelp crab
Purple shore crab

30. True Crabs
Red crab
Oregon cancer crab

31. Other “Crabs”
Hairy hermit crab
Pacific mole crab

32. Shrimp
Broken (Stiletto)back shrimp

33. Isopods & Amphipods
Vosnesensky’s isopod
Sand flea

34. Sea Spiders
Stearns’ sea spider

35. Sea Spiders

36. Sea Spiders

37. Sea Spiders

38. Phylum Arthropoda Class: Merostomata--horeshoe crabs
Class: Pycnogonida--sea spiders
Class Crustacea:
Subclass: Branchiopoda--fairy shrimp, brine shrimp
(2) Subclass: Copepoda—copepods
(3) Subclass: Cirripedia—barnacles
(4) Subclass: Malacostaca:
Order: Stomatopoda--mantis shrimp
Order: Euphausiacea—krill
Order: Decapoda--shrimps, lobsters, crabs

39. Stop