1. Phylum Arthropoda (The Arthropods)
By far and away, the most successful animal group ever to live
Consists of over 1 million named species, 2 of every 3 animals are arthropods.
Inhabit all ecosystems

2. General characteristics
All have a hard exoskeleton
Composed of protein and chitin
Allows for great variation in function - biological "swiss army knives"
Must molt as they grow
Limits their size
Have well developed body segments and appendages
Have well developed sensory organs including true eyes and antennae
Have open circulatory systems & special gas exchange organs

3. Subphylum Chilicerata (arachnids, horseshoe crabs & sea spiders)
Divided into 3 classes; Arachnida, Merostomata & Pycnogonida
Body divided into 2 regions
Abdomen
Cephalothorax (fused head & thorax)
Lack jaws
Have 6 appendages & no antennae
First appendages form chilicerae (frequently fangs)

4. Class Arachnida (Spiders, Scorpions, Ticks & Mites)
Very diverse class
Most species parasitic or predatory
Many possess book lungs for gas exchange
Spiders are able to produce a strong polymer - silk
Chilicera in form of fangs

5. Spiders

6. More Spiders…
Tarantula
Black Widow

7. For the true arachnophobe…
The brown recluse and its bite wounds

8. The Camel Spider

9. Ticks & Mites

10. Ticks & Lyme Disease…

11. Common Mites
Dust Mite
Common Mite

12. Scorpions

13. Class Picogonida (Sea Spiders)

14. Class Merostomata Ancient group of species
Changed little over 350 million years
Aquatic, mostly found on Atlantic & gulf coasts of United States

15. Subphylum Uniramai (3 Classes)
Class Insecta (insects)
Class Chilopoda (Centipedes)
Class Diplopoda (Millipedes)

16. Class Insecta (the insects)
Far & away the most diverse of animal groups
More types of insects alone than all other animal groups combined
Inhabit all terrestrial & freshwater ecosystems.
Success largely attributed to coevolution with flowering plants.

17. Insect Body Plan Insects have 6 legs 3 body parts Head Thorax Abdomen
Most insects have wings, however in many species these are vestigial
Have advanced excretory system composed of malphygian tubules
Exchange gasses through a complex tracheal system

18. Vision
Have complex compound eye which is usually extremely sensitive to motion and allows 3600 vision
Most insects see well into the UV spectrum

19. Feeding / Mouthparts
Insects usually have specialized jaws/mouthparts suited to their ecological niche

20. Metamorphosis
Most insects undergo a process of metamorphosis - 2 types
Incomplete metamorphosis
Larva similar to adult, with differing body proportions
Undergoes a series of molts resulting in adult phenotype

21. Complete Metamorphosis
Larva is very unlike adult phenotype
Envelopes self in a coccoon or chrysalis where body breaks-down and reforms into adult form.

22. Classes Chiopoda & Diplopoda
Millipedes (diplopoda) are segmented worm-like animals
Have 2 pairs of legs per segment
Primarily herbivores & decomposers
Centipedes (Chilopoda)
Usually terrestrial carnivores
Have 1 pair of antennae
Are often poisonous, using modified front claws to immobilize prey

23. Centipedes vs. Millipedes

24. Subphylum Crustacea
Includes crabs, lobsters, crayfish, shrimp, krill & barnacles
Over 40,000 species
Appendages are often highly specialized
Gas exchange is usually through gills
Many species taste delicious in butter

25. Some Crustaceans
Crayfish
Marine Maine Lobster

26. Crabs

27. Barnacles