Class Arachnida Spiders, scorpions, mites, and ticks

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Class ArachnidaSpiders, scorpions, mites,
and ticks

• 30,000 species of spiders - 12 poisonous to
  humans
• 2 body regions - cephalothorax and abdomen
• 2-6 silk glands in the abdomen-pass liquid silk
  to spinnerets which spin it into thread.
• No antennae, Simple Eyes -usually 8
• Ticks mites-1 body part (All fused)
• Use book lungs for gas exchange

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Class ArachnidaSpiders, scorpions,
mites, and ticks

• 6 pairs of appendages-
  
• 2 Chelicera-fangs (hold food inject poison)
  
• 2 Pedipalps for handling food, sensing, and
  reproduction (carry sperm)
• 8 legs

Chelicera Pedipalps
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Class Crustacea Crayfish, shrimp, lobsters,
barnacles, crabs

• Gills for breathing- found underneath
  cephalothorax.
• Large mandibles for crushing food- jaws open side
  to side not up and down
• 2-pairs of antennae for sensing.
• 2 stalked compound eyes for tracking predators.
• 5 pairs of appendages for walking, sensing prey,
  and cleaning other appendages.
• Pill bugs - Most common terrestrial crustacean-
  found in damp soils.

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Crustacean Example - Crayfish
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Centipedes and Millipedes

• Class Chilopoda- Centipedes with 1 pair of legs
  per segment (15 - 181 segments)
• Carnivorous- Snails, slugs and worms.and bite
  humans.
• Class Diplopoda - Millipedes with 2 pairs of legs
  per body segment (more than 100 segments)
• Herbivorous - Roots and leaves
• Dont bite but spray a smelly-fluid from stink
  glands
• Both use book lungs for gas exchange.

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Class Insecta

• Largest class of arthropods.
• Only invertebrates that fly.
• 3 body parts- head-thorax-abdomen
• Spiracles - tracheal tubes for breathing
• Open circulatory system
• 3-pairs of legs, antennae, and both simple and
  compound eyes
• Tympanum in abdomen for hearing
• Some with wings - one or two pair
• Malpighian tubules to excrete dry wastes
  (conserve water)

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Metamorphosis

• Series of changes in body structures controlled
  by chemicals.
• Complete Metamorphosis- (butterflies-moths)
• Egg--gtlarva--gtpupa--gtadult
• Larva - Free living worm-like stage
• Pupa - Period of reorganization where larval
  parts are replaced by adult parts.

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Metamorphosis

• Incomplete Metamorphosis
• ( crickets, grasshoppers)
• Egg gt nymph gt molt gt nymph gt molt gt nymph gt molt
  gtadult
• Nymph - Small adult form that lacks appendages
  and cannot reproduce
• With each
• molt it becomes
• more adult-like