2. The Arthropods Chapter 33

3. General statistics u Most numerous and successful phyla u 400,000 known plant species u 250,000 known non-arthropod animals u Over 1,000,000 species of arthropods.

4. 5 classes of arthropods

5. General characteristics u Arthropoda: u From the Greek word arthron meaning “joint” and poda meaning “foot” u 1) Jointed appendages used for crawling, swimming, flying, etc.

6. More characteristics 2. Possess an exoskeleton Made up of protein and chitin Helps to waterproof and prevent water loss Main disadvantage: exoskeleton does not “grow” with the organism. Must be shed. molting

7. u 3. Segmented body u 4. Well developed nervous systems u 5. Open circulatory system

8. Class Crustacea uLuLobsters, crayfish, crabs, shrimp. uMuMostly marine, some fresh water. uAuAll have 2 pairs of antennae on the head and 2 body regions.

9. The crayfish u Cephalothorax: fusion of the head and thorax u Antennules: first pair of appendages attached to the head. Shorter of the two pairs of antennae l Used for touch, taste, and balance

10. More appendages u 2 nd pair : antennae (long) used for touch and tasting u Mandibles (jaws) 1 pair. Used for crushing food u Maxillae: 2 pairs. Used to handle food u Maxillipeds: 3 pairs. Touch, taste, handling of food

11. Chelipeds u Large first legs where claws are found. u Used for defense and grasping prey.

12. and more appendages u Walking legs (4 pairs) u Swimmerets : appendages found on the underside of the abdomen. u Used for swimming and carrying eggs and young.

13. Internal Structure  NUTRITION u Food is caught with the chelipeds, crushed by the mandibles and passed into esophagus. u Food then digested and wastes passed out the anus.

14. Excretion u Wastes from the blood are removed by the green glands in the head.

15. Circulation and respiration u Possess a dorsal heart. u Open circulatory system (no capillaries nor veins) u Arteries dump blood into open spaces, sternal sinus collects old blood and channels it to gills to pick up oxygen.

16. u Hemocyanin = copper containing pigment in the blood that aids in transport of oxygen. u Gasses are exchanged at gills:

17. Nervous system u Well developed sensory organs u Compound eyes, many sensory hairs u Statocysts: sacs at the base of the antennules that aids in balance.

18. Reproduction u Separate sexes. Can determine sex by looking at first pair of swimmerets. u Male will have enlarged first pair of swimmerets to transfer sperm to seminal receptacle of female during the fall. u Eggs attach to swimmerets and hatch in the spring. u Young stay attached until self sufficient.

19. Baby crayfish:

20. Class Chilopoda (centipedes) u “centipede” literally means 100 feet u Usually 30 to 60 legs, can be as many as 350 legs u A distinct 6 segmented head u Worm-like body with similar segments.

21. More centipede facts u All body segments have one pair of legs except the one behind the head and the last two. Fairly fast crawlers u Feed on insects using poison claws. u Usually found in dark damp places l Under logs and rocks, in basements

22. Class diplopoda (millipedes) u Literally 1000 legs although no species has this many legs. World record is 750 legs. u Usually anywhere from 100 to 300 legs. u Two pairs of legs per body segment except for the last two segments. Slow moving u No poison claws; feed on decaying plant material.

23. Class arachnida u Spiders, scorpions, ticks, and mites u Mostly free-living. A few parasitic u Some are harmful to humans (poisonous cause disease) u Mostly helpful l Get rid of pests like mosquitos

24. Ticks u Can cause disease ex. u Spotted Rocky Mt. Fever u Lyme Disease

25. Lyme Disease u Carried by deer ticks. Caused by a bacterium. u Usually in wooded areas of Mid-Atlantic states and New England.

26. spiders u 2 body segments 1) Cephalothorax (6 pairs of appendages) 2) Adbdomen u No antennae or Chewing jaws

27. chelicerae u First pair of appendages u Also known as the “fangs” of a spider u Will inject a poison into its prey.

28. pedipalps u Found between the first pair of legs and the chelicerae. u Used for sensing chemicals and touch u Used to manipulate food.

29. Abdomen appendages: u 4 pairs of walking legs u Book lungs = respiratory organs on underside of abdomen u Spinnerets: posterior end of abdomen, used to make silk for webs and raising and lowering themselves.

30. Class insecta Most successful class of arthropods: 30 orders Live in all habitats High reproductive rates (all reproduce sexually) Small in size Only invertebrates capable of flight

31. Why is flight such an advantage?  Escape form enemies  Search for food  Allow insects to inhabit environments not inhabited by other organisms.  Less competition for natural resources.

32. 3 body regions: 1. Head (mouthparts, antennae, eyes) 2. Thorax (3 pairs of legs, wings) 3. Abdomen (respiratory structures)

33. Specialized structures: uMuMouthparts 2 main types:

34. legs u Used for swimming, collecting pollen. Defense, grasping prey, jumping

35. Incomplete metamorphosis u Series of changes where an insect grows from eggs to a nymph to an adult u Nymph = immature form that closely resembles the adult form except for certain features. u Examples: grasshoppers, crickets

36. Complete metamorphosis u 4 stages: u Eggs, larva, pupa, adult u Larval stage examples: caterpillars, maggots u Pupa: cocoon u Changes are controlled by hormones. u ex.

37. Grasshopper (order Orthroptera) uHuHead u2u2 large compound eyes u3u3 simple eyes u1u1 pair of antennae uMuMouthparts located outside the mouth(mandible, maxilla, special tongue- like organ)

38. Thorax u 3 separate segments to the thorax with each possessing a pair of legs u Each leg has five segments ending in a clawed tarsus or foot u 1 st and 2 nd pairs of legs are for crawling. u Last pair used for jumping u 2 pairs of wings

39. Abdomen uMuMade up of 10 segments uEuEach segment has one pair of spiracles (openings into air tubes) u1u1 pair of tympanum (hearing organs) urureproductive organs

40. Female abdomen u Ovipositor = hard four pointed organ at the base of the abdomen used to dig holes for burying eggs.

41. Harmful effects of insects: uCuCause millions of dollars in crop damage. ueuexamples: uCuCorn smut, rootworm, locusts, tent caterpillars

42. Images:

43. Transmit diseases u Malaria = transmitted by mosquitoes u West Nile virus = also mosquitoes u West West Nile link

44. Destroy property u Cockroaches termites moths

45. Economic value of insects: u Help pollinate fruit trees u Produce honey u Kill other harmful insects u Eat dead plant and animal material

46. Ways to kill insects: u Most common: insecticides u Trap and sterilize males u Genetic engineering l Bt corn

47. Phylum Echinodermata u Literally means “spiny-skinned” u All marine u Examples:

48. characteristics u Well developed coelom u Endoskeleton u Simplest organism showing embryological formation of the anus before formation of the mouth. u Radial symmetry

49. starfish uUuUsually five arms but can possess up to 20 arms uEuExtensive water-vascular system uWuWater will enter through the sieve plate and pass through a series of canals into each arm.

50. Tube feet u Small water filled tubes or projections on the ventral surface used for locomotion, respiration, grabbing prey, and digestion.

51. More starfish facts u Feed on clams and oysters u Skin gills = small finger-like appendages on the surface of starfish that is a site for respiration u Separate sexes  Can regenerate lost arms. An entire new starfish can grow as long as part of the central disk is present.

52. Assignment: u Page 730 u 1-17,20,21,22,25,26,27,30,32