Phylum Arthropoda

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Phylum Arthropoda

• insects, spiders, scorpions, ticks, mites,
  centipedes, millipedes, and crustaceans
• largest phylum in the animal kingdom one million
  species recorded est. gt 30,000,000
• mostly small active (complex behaviors)
• ecologically diverse economically important

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Positive Impacts

• food for humans
• pollinators
• decomposers
• silk, wax, honey
• predators prey- integral part of the food web
• bioindicators
• biological control

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Negative Impacts

• competitors
• pests
• disease vectors
• parasites
• venomous

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General Features

• eucoelomate, protostomes
• exoskeleton - support protective
• water loss, mechanical injury, chemical injury,
  UV barrier
• made of chitin- polysaccharide similar to
  cellulose strong indigestible
• protein, lipid, CaCO3 water and gas
  impermeable
• ecdysis - molting/shedding

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Exoskeleton

• epicuticle
• procuticle
• sclerotization
• resilin

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Metamerism

• conspicuous segmentation
• repetition of tissues organs

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Tagmatization

• segments fuse together into body parts
• head
• cephalothorax
• thorax
• abdomen

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Arthropod Features (cont.)

• jointed appendages (specialization)
• locomotion, sensation, feeding
• generally one pair/segment
• complex muscular system
• complete complex digestive system

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Circulation Respiration

• open circulatory system
• dorsal contractile heart
• vessels
• hemocoel
• respiration
• body surface diffusion
• trachae- respiratory exchange tubes spiricles-
  external openings
• gills book lungs- folded epithelium covered by
  chitin

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Nervous System

• nervous system annelid-like
• sensory system well developed
• compound eyes ocelli
• tympanum
• tactile chemo- receptors
• statocysts

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Excretory Reproductive Systems

• Excretion
• coxal glands- merostomata, arachnids
• antennal glands-crustacea
• maxillary glands-crustacea
• reproduction
• dioecious
• internal fertilization
• oviparous, oviviparous viviparous
• direct indirect development
• parthenogenesis

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Sub-Phylum Trilobitamorpha Class Trilobita

• extinct Paleozoic
• benthic scavengers
• segmented
• compound eyes
• biramous appendages

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Trilobites
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Trilobite Diversity
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Biramous Appendages
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Sub-phylum Chelicerata

• eurypterids, horseshoe crabs, spiders, and ticks,
  and mites
• no antennae or mandibles
• chelicerae - tear food, venom injection,
  secrete enzymes
• (6) pair of appendages pedipalps
• predators/carnivores

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Class Merostomata Horseshoe Crabs
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Class Arachnida

• first terrestrial metazoans
• spiders, scorpions, ticks, and mites

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Order Aranae (spiders)

• 35,000 species
• cephalothorax no external segmentation
• pedipalps- appendages used to hold food mating
• silk (prey capture, egg case, ballooning)
• book lungs, trachae or both

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Spider Anatomy
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Internal Structure
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Venomous Species in North America
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Day 3
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Day 6
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Day 9
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Day 10
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Order Scorpionida

• secretive nocturnal
• mostly harmless
• stinger on the telson
• pectines
• chelicera
• chilipeds

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Order Pseudoscorpiones
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Order Acari (Acarina)

• mites ticks
• reduced segmentation
• parasites
• important disease vectors
• Lyme Disease
• Rocky Mtn. Spotted Fever
• Ixodidae- hard ticks

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Tick Hypostome
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Parasitic Mites
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Scabies