This document classifies arthropods into three subphyla: Trilobitomorpha, Chelicerata, and Mandibulata. Trilobites were diverse marine invertebrates that lived 500-250 million years ago. Chelicerates include spiders, scorpions, ticks, and sea spiders and have two body segments, pedipalps for holding prey, and book lungs. Mandibulatans include insects, centipedes, millipedes, and crustaceans and have mandibles for chewing and three body segments in insects.

1. ARTHROPOD CLASSIFICATION

2. SUBPHYLUM TRILOBITOMORPHA
• Trilobites
• Diverse group of marine invertebrates who lived during the 500 -250
million years ago.
• Well preserved fossil record. (Why?)
• Ancestor to modern arthropods

3. SUBPHYLUM CHELICERATA
• Class Merostomata – Horseshoe Crabs
• Class Arachnida – Spiders, Scorpions, Ticks
• Class Pycnogonida – Sea Spiders

4. SUBPHYLUM CHELICERATA
• No antenna
• Two body segments (cephalothorax, abdomen)
• First pair of appendages (chelicera) adapted for feeding
• Second pair of appendages (pedipalps) to hold prey
• Book lungs/book gills for respiration
• Four pairs of walking legs

5. SUBPHYLUM MANDIBULATA
• Class Myriapoda
• Order Chilopoda (Centipedes)
• Order Diplopoda (Millipedes)
• Class Insecta
• Subclass Apterygota (Wingless Insects)
• Subclass Pterygota (Winged Insects)
• Class Crustacea
• Subclass Malacostraca (Crabs, Lobsters, Shrimp, Woodbugs)
• Subclass Cirripedia (Barnacles)
• Subclasses Ostracoda, Copepod (Planktonic Crustaceans)

6. SUBPHYLUM MANDIBULATA
• Head appendages are modified as mandibles for chewing or grinding.
• Class Myriapoda
• Order Chilopoda (Centipedes)
• One pair of walking legs per segment
• Flat body, fast moving
• Some poisonous
• Carnivores
• Order Diplopoda (Millipedes)
• Two pairs of walking legs per segment
• Round body, slow movers
• Herbivores

7. SUBPHYLUM MANDIBULATA
• Class Insecta
• Three pairs of walking legs (uniramous)on thorax
• One pair or antenna
• Three body segments
• May have wings (only flying invertebrates)

11. MOSQUITO

18. SUBPHYLUM MANDIBULATA
• Class Myriapoda
• Order Chilopoda (Centipedes)
• Order Diplopoda (Millipedes)
• Class Insecta
• Subclass Apterygota (Wingless Insects)
• Subclass Pterygota (Winged Insects)
• Class Crustacea
• Subclass Malacostraca (Crabs, Lobsters, Shrimp, Woodbugs)
• Subclass Cirripedia (Barnacles)
• Subclasses Ostracoda, Copepod (Planktonic Crustaceans)

19. SUBPHYLUM MANDIBULATA
• Class Crustacea
• Two or three body segments
• 4-5 pairs of walking legs
• 2 pairs of antenna

20. BARNACLES