Arachnids

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Arachnids

• Section 30.2

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Features of Arachnids

• Spiders, scorpions, ticks, mites, daddy longlegs
• Cephalothorax and abdomen
• No antennae
• 1st pair of appendages are chelicerae modified
  into pincers or fangs
• 2nd pair of appendages are pedipalps modified
  to catch and handle prey
• No jaws ? inject prey with poison to liquefy it

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Spider fangs
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Some arachnids have pincers
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Spiders

• Chelicerae modified into fangs
• Poison glands secret toxin through the fangs that
  paralyzes or kills the prey
• Only two U.S. spiders are dangerous black widow
  and brown recluse
• Strands of silk are produced in the spinnerets in
  the abdomen

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Black Widow spider
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Brown Recluse Spider
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Brown Recluse Spider bite
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Webs are made from silk produced in spinnerets
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Computer enhanced photo of spider spinnerets
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Scorpions and Mites

• Scorpions stinger on the end of the abdomen
• Pedipalps are pincers
• Mites largest group of arachnids
• Head, thorax and abdomen are fused into
  unsegmented body
• Some are plant or animal parasites (ticks)

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Scorpion
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House dust mite
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Deer ticks can carry Lyme disease