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ARTHROPODS

ARTHROPODS. Arthropods. (“jointed foot”) ¾ of all animals on planet Earth! 750,000+ species….why so numerous and successful?. 1: Reproduce fast & in large numbers. opportunity for variation is therefore great

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ARTHROPODS

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  1. ARTHROPODS

  2. Arthropods • (“jointed foot”) • ¾ of all animals on planet Earth! 750,000+ species….why so numerous and successful?

  3. 1: Reproduce fast & in large numbers • opportunity for variation is therefore great • take advantage of different food sources…pass through developmental stages such as ‘larva’ and ‘adult’ in metamorphosis

  4. #2: Exoskeleton (outside) Changed the single fortress (shell) to a flexible suit of armor • Protection; barrier against loss of body fluids; must be recycled and shed (molted!) to make room for growth

  5. #3: Segmentation • More flexible movement • Creates lots of interior ridges for muscle attachments, going in different directions

  6. #4: Striated Muscles • voluntary and quick contracting (but, they get tired quickly….need lots of oxygen to burn food for quick energy!

  7. #5: Efficient air moving systems • Gills in water; book lungs for spiders; tracheae (pipes) for insects

  8. #6: jointed appendages • modified for locomotion (legs, wings), eating (claws, mouthparts), sensing (antennae)

  9. #7: Sense Organs • eyes (simple or compound); hair on legs, body, antennae; chemical senses

  10. Arthropod Groups (taxa) The arthropods are divided into two large groups that exist today: Chelicerates and Mandibulates

  11. Chelicerate Arthropod Characters: • Pincher-like mouthparts - chelicerae - and pedipalps • NO antennae • Two body regions, usually - cephalothorax & abdomen • Four pairs of legs • Horseshoe crabs and arachnids are only living groups

  12. Orders of Arachnids • Scorpions • Pseudoscorpions • Daddy Long-Legs • Mites & Ticks • Spiders

  13. Pseudoscorpion Tick (a mite) Scorpion Wolf Spider Daddy-long-legs

  14. Scorpion Anatomy

  15. chelicerae eyes pedipalp

  16. Pseudoscorpion

  17. Mite and Tick Body Regions pedipalps & chelicerae cephalothorax abdomen

  18. American dog tick male Blacklegged (deer) tick female

  19. American dog tick female laying egg mass (1000-2000 eggs!).

  20. Clover mites Twospotted spider mites Predatory mite

  21. daddy long-legs cephalothorax abdomen

  22. Spider Anatomy pedipalp chelicera (fang) cephalothorax narrow waist abdomen

  23. Abdomen Cephalothorax Chelicera (fang) Pedipalp Jumping Spider

  24. Wolf spider with egg case Spitting spider Orb-weaving spider Tarantula

  25. Black widow with egg case Brown recluse

  26. Mandibulate Arthropod Characters: • Mouthparts are mandibles - normally chewing sideways • One or two pairs of antennae • Various body region arrangements - cephalothorax & abdomen / head & trunk / head, thorax & abdomen • Variable leg numbers • Insects, crustaceans & myriapods

  27. Classes of Myriapods (many legged arthropods) (all have one pair of antennae, a head region, and trunk with many pairs of legs, use trachea) • Diplopoda - millipedes • Chilopoda - centipedes

  28. Myriapods [one pair of antennae, head & trunk regions, trunk with many pairs of legs] Millipede (Diplopoda) Two pair of legs per visible segment, attached under body. Centipede (Chilopoda) Pair of fangs under head, one pair legs per visible segment - attached to side of body. No fangs, no eyes, legs attached to side of body.

  29. Millipede (Diplopoda) Centipede (Chilopoda) Garden centipede

  30. Insecta Class • 3 segments  head, thorax, abdomen • 1 pair of antennae • Special characteristics: • Wings • Pheromones • Metamorphosis

  31. Phereomones • Chemical signals • Used for • Marking trails • Identification of organisms • Signaling trouble • Signaling sexual readiness

  32. Metamorphosis • Incomplete • Born as a smaller version of the adult • 3 stages • Egg  nymph  adult • Nymph molts many times into different “stage” of nymph

  33. Metamorphosis • Complete • Born as a complete different version than adult • 88% of metamorphosis • 4 stages • Egg  larva  pupa  adult

  34. Classes of Crustacea • mostly marine, fresh water, a few terrestrial • all have two pair of antennae • five or more pairs of legs • segmented abdominal appendages • head & trunk or cephalothorax & abdomen body arrangement • have gills • Sowbugs or pillbugs • Sand fleas • Barnacles • Crabs, lobster, shrimp

  35. Crayfish cephalothorax (Decapoda) Sowbug (Isopoda), a terrestrial crustacean

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