Phylum Arthropoda

1. Phylum Arthropoda

2. General Characteristics • Arthropod = jointed feet • Largest group of animals • 80% of described species • 30-50 million species • Most varied

3. General Characteristics Con’t • Metamerism (body divided into segments) • Head, abdomen, thorax • Paired, jointed appendages • Ecdysis-molting (growth) • Open Circulatory System (means no vessels) • Complete digestion tract

4. Metamerism (Body Segments) 2 Segments 3 Segments

5. General Characteristics Con’t • Ventral Nervous System • True exoskeleton • Metamorphosis • 5 Subphylum • Trilobitomorpha, Myriapoda, Chelicerata, Crustacea, Hexapoda

7. Exoskeleton • Functions of exoskeleton • protection • Gas exchange • Minimize H2O loss • Muscle attachment

8. Exoskeleton Structure • Composed of chitin – a carbohydrate • Epicuticle: outer layer • Water proof • Procuticle: inner layer • Made of chitin

9. Ecdysis (molting) • 3 step process • 1. Enzymes digest old exoskeleton • 2. New exoskeleton secreted • New exoskeleton is soft • 3. Scleratization (hardening)

10. Ecdysis (molting) • Molting is important for arthropod growth • Can’t grow in a suit of armor • Is also a dangerous time for arthropods • Typically animals about to molt, will go into hiding just before the process begins

11. Metamorphosis • Changes in body form from larval to adult • Ex. Butterfly, Dragonfly • Reduces competition for food and living space (*)

13. Subphylum Trilobitomorpha • MOST PRIMITIVE! • All extinct and marine • Body with 3 sections

14. Subphylum Myriapoda • Myriapoda- “many legs” • Millipedes, centipedes • Paired legs • Terrestrial

15. Millipedes vs. Centipedes • Millipedes: • Herbivorous • Appear to have 2 legs per segment • Slow • Non-venomous

16. Centipedes • Carnivorous • Have only 1 pair of legs per segment • Faster • Venomous

17. Subphylum Chelicerata • Spiders, mites, ticks, scorpions, horseshoe crabs, • Have chelicera- fangs • 2 Segments • Cephalothorax (head-chest) • Abdomen

18. Feeding • Appendages: • 1st pair- chelicera: feeding (often fang-like) • 2nd pair- Pedipalps: feeding, locomotion, reproduction

19. Subphylum Hexapoda INSECTS

20. General Characteristics • Hexapoda = “six legs” • Includes the class Insecta • 30 million species • 27 Major orders • We will only learn 8

21. General Characteristics Con’t • 3 pairs of legs • 6 total • 1 pair of antennae • Most have 2 pairs of wings • Compound eyes (2) and Oscelli (3 in middle) • 3 part body plan • Head, Thorax, Abdomen

22. Insect Flight • Is a unique trait to the insects • Different insects have wing modifications for specific functions

23. Economic Importance • Parasites • Ticks, fleas • Are considered agricultural pests. • 1949-European corn borer caused $349 million in damage to the US corn crop

24. Economic Importance Con’t • Provide goods • Honey • Beeswax • Yummy (to certain cultures) • Silk • Dyes

26. Economic Importance Con’t • Also are vectors for many diseases • Bubonic plague (flea) • Malaria (mosquito) • West Nile Virus(mosquito) • African Sleeping Sickness (Tsetse fly)

27. Subphylum Crustacea

28. General Characteristics • Includes crabs, lobsters, crayfish, shrimp, and barnacles • Carapace – “shell” that protects organs (like a turtle) • Biramous Appendage: branched Y-shaped appendages

31. General Characteristics Con’t • Habitat • Marine and Freshwater • 2 or 3 body segments • Head, Thorax, and Abdomen • OR • Cephalothorax and Abdomen

32. Reproduction • Sexual reproduction (most external, some internal) • Few monoecious (hermaphroditic)

33. Females retain eggs until hatching

34. Economic Importance • Tasty—people like to consume them

35. Ecological Importance • Scavengers-eat dead material • Basis of food chain(shrimps, barnacles) • Keystone species