1. End Show Slide 1 of 42 Copyright Pearson Prentice Hall Biology

2. End Show Slide 2 of 42 Copyright Pearson Prentice Hall 28–2 Groups of Arthropods

3. End Show 28–2 Groups of Arthropods Slide 3 of 42 Copyright Pearson Prentice Hall 28–2 Groups of Arthropods Arthropods are classified based on the number and structure of their body segments and appendages—particularly their mouthparts. The three major groups of arthropods are: crustaceans spiders and their relatives insects and their relatives

4. End Show 28–2 Groups of Arthropods Slide 4 of 42 Copyright Pearson Prentice Hall Crustaceans Crustaceans are primarily aquatic. This subphylum includes crabs, shrimps, lobsters, crayfishes, and barnacles.

5. End Show 28–2 Groups of Arthropods Slide 5 of 42 Copyright Pearson Prentice Hall Crustaceans Crustaceans typically have two pairs of antennae, two or three body sections, and chewing mouthparts called mandibles. Abdomen Mandible Second antenna First antenna Cephalothorax

6. End Show 28–2 Groups of Arthropods Slide 6 of 42 Copyright Pearson Prentice Hall Crustaceans In a crustacean, the first two pairs of appendages are antennae. First antenna Second antenna

7. End Show 28–2 Groups of Arthropods Slide 7 of 42 Copyright Pearson Prentice Hall Crustaceans The third pair of appendages are the mandibles. A mandible is a mouthpart adapted for biting and grinding food. Mandible

8. End Show 28–2 Groups of Arthropods Slide 8 of 42 Copyright Pearson Prentice Hall Crustaceans Decapods have five pairs of legs. In crayfishes, the first pair of legs, called chelipeds, have large claws that catch, pick up, crush, and cut food. Cheliped Walking legs

9. End Show 28–2 Groups of Arthropods Slide 9 of 42 Copyright Pearson Prentice Hall Crustaceans Along the abdomen are several pairs of swimmerets, which are flipperlike appendages used for swimming. Swimmerets

10. End Show 28–2 Groups of Arthropods Slide 10 of 42 Copyright Pearson Prentice Hall Crustaceans The final abdominal segment is fused with a pair of paddlelike appendages to form a large, flat tail. Tail

11. End Show 28–2 Groups of Arthropods Slide 11 of 42 Copyright Pearson Prentice Hall Spiders and Their Relatives Horseshoe crabs, spiders, ticks, and scorpions are chelicerates. Chelicerates lack antennae.

12. End Show 28–2 Groups of Arthropods Slide 12 of 42 Copyright Pearson Prentice Hall Spiders and Their Relatives Chelicerates have mouthparts called chelicerae and two body sections, and nearly all have four pairs of walking legs. Fanglike chelicera

13. End Show 28–2 Groups of Arthropods Slide 13 of 42 Copyright Pearson Prentice Hall Spiders and Their Relatives Chelicerae contain fangs and are used to stab and paralyze prey. Fanglike chelicera

14. End Show 28–2 Groups of Arthropods Slide 14 of 42 Copyright Pearson Prentice Hall Spiders and Their Relatives Pedipalps are longer than the chelicerae and are usually modified to grab prey. Pedipalp

15. End Show 28–2 Groups of Arthropods Slide 15 of 42 Copyright Pearson Prentice Hall Spiders and Their Relatives Chelicerates are divided into two main classes. Merostomata includes horseshoe crabs. Arachnida, or arachnids, includes spiders, mites, ticks, and scorpions.

16. End Show 28–2 Groups of Arthropods Slide 16 of 42 Copyright Pearson Prentice Hall Spiders and Their Relatives Horseshoe Crabs Horseshoe crabs first appeared more than 500 million years ago and have changed little since that time.

17. End Show 28–2 Groups of Arthropods Slide 17 of 42 Copyright Pearson Prentice Hall Spiders and Their Relatives Spiders Spiders capture and feed on animals ranging from other arthropods to small birds.

18. End Show 28–2 Groups of Arthropods Slide 18 of 42 Copyright Pearson Prentice Hall Spiders and Their Relatives All spiders produce silk. Spiders spin silk into webs, cocoons for eggs, and wrappings for prey. Silk Silk glands

19. End Show 28–2 Groups of Arthropods Slide 19 of 42 Copyright Pearson Prentice Hall Spiders and Their Relatives They do this by forcing liquid silk through spinnerets, which are organs that contain silk glands. Spinnerets

20. End Show 28–2 Groups of Arthropods Slide 20 of 42 Copyright Pearson Prentice Hall Spiders and Their Relatives Mites and Ticks Mites and ticks are small arachnids that are often parasitic. Their chelicerae and pedipalps are specialized for digging into a host’s tissues and sucking out blood or plant fluids.

21. End Show 28–2 Groups of Arthropods Slide 21 of 42 Copyright Pearson Prentice Hall Spiders and Their Relatives Scorpions Scorpions inhabit warm areas around the world. Scorpions have pedipalps that are enlarged into claws. Scorpions chew their prey.

22. End Show 28–2 Groups of Arthropods Slide 22 of 42 Copyright Pearson Prentice Hall Insects and Their Relatives Centipedes, millipedes, and insects are uniramians. Uniramians have jaws, one pair of antennae, and unbranched appendages.

23. End Show - or - Continue to: Click to Launch: Slide 23 of 42 Copyright Pearson Prentice Hall 28–2

24. End Show Slide 24 of 42 Copyright Pearson Prentice Hall 28–2 The two main groups of chelicerates are a.spiders and scorpions. b.horseshoe crabs and spiders. c.horseshoe crabs and arachnids. d.arachnids and insects.

25. End Show Slide 25 of 42 Copyright Pearson Prentice Hall 28–2 Insects are part of the group a.crustaceans. b.uniramians. c.chelicerates. d.diplopods.

26. End Show Slide 26 of 42 Copyright Pearson Prentice Hall 28–2 Most mites and ticks are a.parasites. b.predators. c.herbivores. d.detritovores.

27. End Show Slide 27 of 42 Copyright Pearson Prentice Hall 28–2 Which of the following is NOT a typical crustacean characteristic? a.either two or three body segments b.chewing mouthparts called mandibles c.chelicerae that paralyze prey d.two pairs of antennae

28. End Show Slide 28 of 42 Copyright Pearson Prentice Hall 28–2 Spiders differ from the other arachnids because they have a.two major body segments and six legs. b.three major body segments and eight legs. c.two major body segments and eight legs. d.three major body segments and six legs.

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