Classes of Arthropods

Dichotomous Key

Anatomy

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OcelliCompoundEye

Cephalothorax

Abdomen

HeadThoraxAbdomen

Antennae

Arachnida

• Antennae absent

• Spiders, ticks, mites, scorpions, etc.

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Black Widow Spider

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Brown Recluse Spider

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Crustacea

• Two pair of antennae present

• Crawfish, crabs, sowbugs, etc.

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Insecta

• One pair of antennae

• Three pairs of legs

• Beetles, butterflies, bees, etc.

Chilopoda

• Many pairs of legs with one pair of legs per body segment

• Poisonous fangs at end of body

• Centipedes

Diplopoda

• Many pairs of legs with two pairs of legs per body segment

• Millipedes

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