Phylum Arthropoda Trilobites, Chelicerates, & Myriapods Donald Winslow 7 March 2008 Hickman et al. 2008 Ch. 19 pp 402-417 Crustaceans: Ch. 20 pp 421-429, 431-437 Insects: Ch. 21 pp 441-464

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

Arthropod respiration Body surface Gills Lungs Tracheae

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

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

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

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

Horseshoe crabs Carapace Abdomen Telson Eyes 10 legs Book gills

Sea spiders Males carry egg masses w/ ovigers Class Pycnogonida

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

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

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

Scorpions Cephalothorax Preabdomen Postabdomen with stinger

Order Opiliones Harvestmen or Daddy Long-legs Scavengers

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

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