1. (insects, crustaceans, spiders, mites)
Diversity of Life
-Arthropoda -
(insects, crustaceans, spiders, mites)

2. Arthropoda - insects, crustaceans, spiders, mites,

3. Arthropoda - abundance

4. Arthropoda – Where did they come from?
Peripatus

5. What about the Onychophora (“velvet worms” )?
Annelid Arthropod
Characteristics Characteristics
-worm-like body -segmented legs
(during embryogenesis)
Peripatus
-paired nephridia -open circulatory system
- hemocoel
- trachea
- oral appendages

6. Arthropoda - What makes them all arthropods?
Arthropods are
• segmented coelomates
• exoskeleton
• jointed appendages

7. Arthropoda - two significant improvements in body architecture
EXOSKELETON
JOINTED APPENDAGES

8. Arthropoda - Exoskeleton
heart
digestive cavity
ventral nerve cord

9. Arthropoda - Exoskeleton
The arthropod exoskeleton is made of chitin (also found in the cell walls of fungi)
Chains of sugars - cross-linked with benzene
N-acetyl - glucosamine
Benzene rings

10. Arthropoda - Exoskeleton=
Laid down in overlapping layers
(like plywood)

11. Arthropoda - Exoskeleton
Advantages:
Protection from drying - allowed invasion of land
Protection from predators -

12. Arthropoda - Exoskeleton
Advantages:
Protection from drying - allowed invasion of land
Protection from predators -
Disadvantages:
Doesn’t permit growth - have to moult
Doesn’t bend - need to insert breaks (joints) in it to permit movement

13. Arthropoda - Body Sections
Thorax - locomotory
Abdomen - digestion and reproduction
Head - sensory and feeding

14. Arthropoda - Classification
THE MAIN GROUPS OF ARTHROPODS
CHELICERIFORMES - spiders, mites, ticks, scorpions
MYRIAPODA - centipedes and millipeds
UNIRAMIA - insects
CRUSTACEA - crabs, lobsters, shrimp

15. Arthropoda - Cheliceriformes
Horseshoe crab
Spider
Scorpion

16. Arthropoda - Cheliceriformes
Characteristics
1. Chelicerae - feeding appendages
2. Head and thorax are fused - cephalothorax
3. Eight legs

17. Arthropoda - Myriapoda
- millipedes and centipedes
Characteristic
- several pairs of legs

18. Arthropoda - Uniramia - the insects
Most common kind of animal - greatest number of species

19. Arthropoda - Uniramia - the insects
Most common kind of animal - greatest number of species

20. Arthropoda - Uniramia - the insects
Most common kind of animal - greatest number of species
Characteristics -
Six legs
2. Distinct head, thorax and abdomen

21. Arthropoda - Uniramia - the insects
Characteristics
3. Wings
Insects are the only invertebrates to have mastered flight

22. Arthropoda - Uniramia - the insects
Characteristics -
3. Two kinds of life cycles
Complete (or holometabolous)
Egg larva pupa adult
Incomplete (or hemimetabolous)
Egg larva adult

23. Arthropoda - Crustacea - lobsters, crabs, barnacles

24. Arthropoda - Crustacea - lobsters, crabs, barnacles
Characteristics -
1. Head and thorax are fused - cephalothorax

25. Arthropoda - Crustacea - lobsters, crabs, barnacles
Characteristics -
2. 10 primary locomotory appendages

26. Arthropoda - Summary of characteristics
Group
Cheliceriformes
Uniramia
Myriapoda
Crustacea
Cephalothorax
Yes No
Number of legs 8 6
20+ 10
Flight
Jointed
appendages