1. Phylum Arthropoda General characteristicsGeneral characteristics –largest group by sheer numbers – total number exceeds that of all other kinds of animals combined –jointed appendages – extensions of the body including legs and antennae –the body is segmented – a pair of appendages is usually attached to each segment

2. body is usually divided into:body is usually divided into: –head –thorax – wings and walking legs attach here –abdomen – also divided into segments –some have the head and thorax fused to form a cephalothorax (spiders, crayfish)

4. Cephalothorax Head Thorax Abdomen Walking legs Mouthparts (feeding) Pincer (defense)

5. have an exoskeleton – hard external covering for protection and support – made mostly of chitinhave an exoskeleton – hard external covering for protection and support – made mostly of chitin –exoskeleton does not grow and body enlarges –exoskeleton must be shed periodically to allow growth – molting –new exoskeleton is soft – arthropod is vulnerable until it hardens –also susceptible to desiccation (drying out)

6. Cephalothorax Head Thorax Abdomen Walking legs Mouthparts (feeding) Pincer (defense)

7. open circulatory system – blood drains into sinusesopen circulatory system – blood drains into sinuses distinct head, often with compound eyes (eye has thousands of individual visual units each with its own lens and retina) – highly sensitive to light, good at detecting motion, can form only crude imagesdistinct head, often with compound eyes (eye has thousands of individual visual units each with its own lens and retina) – highly sensitive to light, good at detecting motion, can form only crude images

8. many have wingsmany have wings most respire through tracheae – network of fine tubes that carry air directly to the cells – air enters through pores called spiraclesmost respire through tracheae – network of fine tubes that carry air directly to the cells – air enters through pores called spiracles

9. Classification: Subphylum Trilobita – extinct organismsSubphylum Trilobita – extinct organisms Subphylum Crustacea – crayfish, lobster, pillbugs, copepodsSubphylum Crustacea – crayfish, lobster, pillbugs, copepods –exoskeleton contains calcium carbonate Subphylum Cheliceriformes – spiders, scorpions, ticks, mitesSubphylum Cheliceriformes – spiders, scorpions, ticks, mites Subphylum Myriapoda – centipedes and millipedesSubphylum Myriapoda – centipedes and millipedes Subphylum Hexapoda – the insectsSubphylum Hexapoda – the insects

10. Subphylum Trilobita

11. Subphylum Crustacea

12. Subphylum Cheliceriformes

13. Subphylum Myriapoda

14. Subphylum Hexapoda

15. Class Arachnida – spiders, scorpions, and mites cephalothorax and abdomen Intestine Heart Digestive gland Ovary Anus Spinnerets Silk gland Gonopore (exit for eggs) Sperm receptacle Book lung Chelicera Pedipalp Poison gland Eyes Brain Stomach

16. Class Arachnida respire through spiracles – air passes to the book lungs (sacs in the abdomen that look like pages in a book)respire through spiracles – air passes to the book lungs (sacs in the abdomen that look like pages in a book) Book lung

17. Class Arachnida Most have 8 simple eyes, some have 4 or 6Most have 8 simple eyes, some have 4 or 6

18. Class Arachnida have spinnerets – produces thread for webs, protecting eggs, catching preyhave spinnerets – produces thread for webs, protecting eggs, catching prey 4 pairs of walking legs4 pairs of walking legs no jaw – they suck food inno jaw – they suck food in Spinnerets

19. Class Insecta entomology – study of insectsentomology – study of insects head, thorax, and abdomenhead, thorax, and abdomen usually have 6 legsusually have 6 legs thorax may have a pair of wingsthorax may have a pair of wings

20. Class Insecta largest group of animals – very successful because:largest group of animals – very successful because: –small size –high rate of reproduction –capable of flight –can occupy almost all types of habitats –classified by number and type of wings

22. Metamorphosis metamorphosis – change from juvenile form to adult formmetamorphosis – change from juvenile form to adult form –incomplete metamorphosis – nymph hatches from egg almost a miniature version of adult (without wings)

23. complete metamorphosis – four stagescomplete metamorphosis – four stages –egg –larva (worm-like) –pupa (cocoon) –adult

24. (a) Larva (caterpillar) (b) Pupa (c) Later-stage pupa (d) Emerging adult (e) Adult