1. Phylum Arthropoda Trilobites, Chelicerates, & Myriapods
Donald Winslow
7 March 2008
Hickman et al. 2008
Ch. 19 pp
Crustaceans: Ch. 20 pp ,
Insects: Ch. 21 pp

2. Phylum Arthropoda Diversity & abundance
Exoskeleton & chitin, ecdysis (molting)
Somites, tagmata, jointed appendages
Complex muscular system, no cilia
Open circulatory system & hemocoel
Mouthparts, complete digestive tract
Excretory glands & Malpighian tubules

3. Arthropod respiration
Body surface
Gills
Lungs
Tracheae

4. Arthropod nervous system
Cerebral ring
Two ventral nerve chains
Complex sensory organs
Ocelli & compound eyes
Complex behavior

5. Arthropod reproduction
Usually dioecious w/ internal fertilization
Oviparous or ovoviviparous or viviparous
Sometimes parthenogenesis
Development often by metamorphosis

6. Phylum Arthropoda Subphylum Trilobita Subphylum Myriapoda
extinct marine animals
Subphylum Myriapoda
Centipedes & millipedes
Subphylum Chelicerata
Horseshoe crabs, spiders, scorpions, etc.
Subphylum Crustacea—crustaceans
Subphylum Hexapoda—insects

7. Subphylum Chelicerata
2 chelicerae, 2 pedipalps
8-10 legs
No mandibles or antennae
Class Merostomata
Subclass Xiphosurida (horseshoe crabs)
Class Pycnogonida (sea spiders)
Class Arachnida
Spiders, scorpions, harvestmen, ticks & mites

8. Horseshoe crabs
Carapace
Abdomen
Telson
Eyes
10 legs
Book gills

9. Sea spiders
Males carry egg masses w/ ovigers
Class Pycnogonida

10. Class Arachnida Order Araneae Order Scorpiones Order Opiliones
spiders
Order Scorpiones
scorpions
Order Opiliones
Harvestmen (Daddy long-legs)
Order Acari
Ticks & mites

11. Spiders Pedicel joins cephalothorax & abdomen
Book lungs and/or tracheae & spiracles
Malphigian tubules & excretory glands
8 ocelli, sensory setae, poison, webs
Brain, suboesophageal ganglion
Sinuses
Sperm from M pedipalps to F receptacle

12. Spider feeding & defense
Insect predation
Dangerous spiders
Black widow
Brown recluse (fiddleback)

13. Scorpions
Cephalothorax
Preabdomen
Postabdomen with stinger

14. Order Opiliones
Harvestmen or Daddy Long-legs
Scavengers

15. Ticks & mites Terrestrial or aquatic, sometimes parasitic
Mouthparts on capitulum
Cephalothorax & abdomen fused
Chiggers, scabies, Lyme disease
Rocky Mountain Spotted Fever
Dust mites, follicle mites

16. Myriapods Head & trunk, many somites Class Chilopoda (centipedes)
Predators, poison fangs, 2 legs per segment
Class Diplopoda (millipedes)
4 legs per abdominal segment