Understanding Insect External Morphology: An Overview

1. External Morphology(after R. Zack, Washington State University) Insects and People External Morphology

2. The body of an arthropod is composed of repeating segments Insects and People External Morphology

3. Tagmosis = the grouping of body segments into functional unitsTagma(ta) = the grouped segments of a functional unite.g., head, thorax, abdomen Insects and People External Morphology

4. The insect body is composed of three distinct tagmata • Head • Thorax • Abdomen Insects and People External Morphology

5. The insect body covering is referred to as an Exoskeleton in both adults and immatures Insects and People External Morphology

6. Protective armor - prevents wear and tear Protection from invasion by pathogens and harmful agents Impermeable to water Base for muscle attachment Does not expand - must be shed in order to grow - molting Advantages and disadvantages of an exoskeleton Insects and People External Morphology

7. The exoskeleton (cuticle) of an insect consists of a number of layers • Epicuticle - non-living • Exocuticle - non-living • Endocuticle - non-living • Epidermis - living Insects and People External Morphology

8. Exoskeleton (cuticle) of an arthropod Insects and People External Morphology

9. Epicuticle - outer-most layer is itself multilayered • Cement • Wax • Outer epicuticle • Inner epicuticle Insects and People External Morphology

10. Exocuticle and Endocuticle • Non-living • Non-cellular • Provide strength and rigidity (chitin) • Provide flexibility (resilin) Insects and People External Morphology

11. Epidermis • Living layer • At maximum depth during molting - secretes substances involved in molting Insects and People External Morphology

12. Rigidity and Flexibility in the Exoskeleton • Sclerite - a plate of the body wall surrounded by sutures or membrane. • Suture - the line of fusion of two plates • Membrane - thin and pliable cuticle Insects and People External Morphology

13. Cuticular Appendages - Seta(e) • Setae are hair-like projections of the cuticle which arise from a trichogen cell. Insects and People External Morphology

14. Cuticular Appendages - Scales • Scales are flattened setae that serve a “covering” purpose” • Wings of butterflies and moths • The bodies of silverfish and some beetles are covered with scales Insects and People External Morphology

15. Cuticular Appendages - Glandular Setae • Glandular setae produce secretions involved in protection or communication Insects and People External Morphology

16. Cuticular Appendages - Spines • Spines are simply outgrowths of the cuticle, not produced by a cell. • Spines may help in grasping, clinging to objects, or in protection Insects and People External Morphology

17. Examples of Spines Insects and People External Morphology

18. The Insect Head • Sensory • Eyes • Ocelli • Antennae • Feeding • Paired mouthparts Insects and People External Morphology

19. The Insect Head Insects and People External Morphology

20. Insect Compound Eyes Insects and People External Morphology

21. More Ommatidia - Better Vision Insects and People External Morphology

22. Insect Ocelli Insects and People External Morphology

23. Insect Antenna(e) Insects and People External Morphology

24. Antennae come in many shapes and sizes Insects and People External Morphology

25. Insect Mouthparts • Vary depending of food eaten and other functional needs • Chewing • Piercing and sucking • Sponging • Siphoning • Chewing and lapping Insects and People External Morphology

26. Chewing Mouthparts Insects and People External Morphology

27. Piercing and Sucking Mouthparts Insects and People External Morphology

28. Piercing and Sucking Mouthparts Mosquito Insects and People External Morphology

29. Sponging MouthpartsSome Flies Insects and People External Morphology

30. Sponging MouthpartsHousefly Insects and People External Morphology

31. Siphoning MouthpartsMoth and Butterfly Adults Insects and People External Morphology

32. Chewing and Lapping MouthpartsBees Insects and People External Morphology

33. The Insect Thorax Insects and People External Morphology

34. The Insect Leg Insects and People External Morphology

35. Leg Modifications Cursorial - Running Insects and People External Morphology

36. Leg Modifications Natatorial - Swimming Insects and People External Morphology

37. Leg Modifications Saltatorial - Jumping Insects and People External Morphology

38. Leg Modifications Raptorial - Grasping Insects and People External Morphology

39. Wings • Insects are among the few animals that can fly - an important development! • Not all insects have wings • Wing type varies - depends on need • Wings are outgrowths of the cuticle Insects and People External Morphology

40. Insects and People External Morphology

41. Membranous Wings Insects and People External Morphology

42. Membranous WingsFlies with haltere Insects and People External Morphology

43. Tegmina“leather-like” forewing Insects and People External Morphology

44. Hemelytron - “half-wing,” forewingTrue Bugs Insects and People External Morphology

45. Elytron(a) - hardened front wing Insects and People External Morphology

46. Scale covered wings Insects and People External Morphology

47. The Insect AbdomenNo walking appendages Insects and People External Morphology

48. OvipositorEgg-laying device Insects and People External Morphology

49. “Stinger”A modified ovipositor Insects and People External Morphology

50. CerciSensory structures Insects and People External Morphology