1. Arthropods
Blue print for Success

2. Arthropod Characteristics
Includes crayfish, lobsters, spiders, mites, scorpions, and insects
Metamerism modified by the specialization of body regions for specific functions (tagmatization)
Chitinous exoskeleton, support and protection
Paired jointed appendages, ventral nervous system
Growth accompanied by molting, metamorphosis
open circulatory system, complete digestive tract

3. Exoskeleton Major reason for Arthropod success
Provides structural support, protection, impermeable surfaces to prevent water loss, and a system of levers for attachment of muscles and movement
Exoskeleton made of two layers
-outer of waxy lipoprotein, prevents dehydration and impermeable to microorganisms
-Inner of chitin, tough polysaccharide and protein
Hardens by deposition of calcium carbonate
Joints had to be incorporated with flexible membrane

4. Exoskeleton

5. Exoskeleton

6. Exoskeleton

7. Exoskeleton Molting is necessary to permit growth, 4 steps
-Enzymes secreted to separate exoskeleton from procuticle
-New procuticle is secreted
-Animal swells by air or water intake, old exoskeleton is split along ecdysal lines
New exoskeleton hardens by addition on calcium carbonate, takes few hours to days and animal is vulnerable, remains hidden

8. Molting

10. molting

11. Exoskeleton

12. Arthropod Anatomy
Hemocoel serves as a cavity for the open circulatory system, the rigid exoskeleton means the coelom is no longer a hydrostatic skeleton
Internal organs are bathed in body fluids to exchange nutrients, wastes and sometimes gases
Metamorphosis- radical change in body form from larva to adult, eliminates competition between larval and adult stages for food

13. Subphylum Trilobitomorpha
Trilobite body has three longitudinal sections thus the name
Dominant life form in the cambrian period 600 million years ago to 345 million years ago
Body was oval, flattened and could roll into a ball for protection
Appendages had two lobes Biramous, inner for walking and outer had spikes for digging

14. Trilobite

15. Trilobite

16. Trilobites

17. Subphylum Chelicerata
Spiders, mites, ticks, horseshoe crabs and sea spiders
Two Tagmata: cephalothorax- contains sensory, feeding and locomotion structures Opisthosoma- contains digestive, reproductive, excretory and respiratory organs
First pair of appendages are pincerlike or chelate (claws) or specialized hollow fangs
Pedipalps- second pair appendages, sensory or feeding, locomotion
Third pair appendages walking legs

18. Class Arachnida
Majority of spiders mites ticks and scorpions are harmless or beneficial to humans
Sea scorpions dated to 425 million years ago and other arachnids date to 345 million years ago
Most are carnivores, either pour or inject enzymes over prey and digested tissue is eaten or sucked in
The front portion of the gut is modified into a pumping stomach, mid gut and hind gut complete digestion

19. Arachnid Anatomy
Nitrogenous wastes are collected with coxal glands or malpighian tubules, both collect nitrogenous wastes from blood
Coxal exit at bottom of posterior appendages
Malpighian tubles deposit excretory wastes into gut tract and exit with digestive wastes
Book lungs exchange gases thru lamella that air passes thru from ventral slit on abdomen
Trachea are tubules which deliver air directly to body tissues exit thru side of abdomen

20. Order Araneae Spiders- largest order of Arachnids
Chelicerae with poison glands and fangs
Six to eight eyes
Spinnerets- conical projections associated with silk glands
Silk is a protein, different types produced for different sections of web
Stronger than Kevlar (steel) Elastic
Safety Line, Ballooning, wrap eggs

21. Spider Multiple Eyes, Setae

22. Spider

23. Order Acarina
Mites and Ticks, many are ectoparasites, some free living terrestrial and aquatic
Chelicerae and pedipalps are modified for piercing, biting, anchoring and sucking
4 pairs of walking legs (adults)
Chiggers larva break down and suck host skin
Dust mites (allergen), scabies tunnel under human skin
Ticks transmit rocky mount. Spotted fever, lyme disease

24. Mite

25. Mite Infestations

26. Tick

27. Removing a tick

28. Ticks on wild Rabbit

29. Horseshoe Crab

30. Sea Spiders

31. Sea Spider

32. Sea Spiders

33. Order Scorpionida Range tropical to warm temperate areas
Nocturnal and secretive Hide under logs, stones during day
Chelicera- Jaws
Chelate pedipalps- Claws
Stinger at base of postabdomen (tail)
Only a few toxic to humans in north Africa Mexico and southwest U.S., most sting like a wasp

34. Scorpion

35. Scorpion with Babies

36. Subphylum Crustacea
Crayfish, shrimp, Lobster, crabs, copepods, cladocerans, fairy shrimp, isopods, amphipods and barnacles
Two pairs of antennae and Biramous appendages
Basal segment- endopodite medial ramus exopodite lateral ramus

37. Class Malacostraca
Crabs, Lobster, Crayfish, shrimp, mysids, Krill, isopods and amphipods
Class Decapoda crab, lobster shrimp
Shrimp muscular abdomen for swimming
Lobster, Crabs crawl on bottom
Abdomen of crabs greatly reduced
Cephalothorax- fusion of head and thorax, shield like Carapace

38. Maine Lobster

39. Florida Lobster

40. Ghost Crabs

42. King Crab

43. Crab Larva Zoea

44. Crayfish Anatomy

45. Crayfish Anatomy
Appendages – 1 first Antennae, shorter second antennae, longer
Appendages 3 mandibles for chewing maxillae food handling maxillae food handling, small gill, blade called gill bailer for circulating water over gills
Appendages 6-8 Maxillipeds sensory and food handling
Appendages 9-13 peropods walking legs
Telson- tail section modified into flipper

46. Crayfish Anatomy
Gills contained in a brachial chamber attached at bottom
Blood through open system into sinuses and then thru gills before returning to heart
Nervous system is ventral and ladder like, giant nerves control tail muscles for escape
Statocyst at base of first antennae, contains cemented sand grains
Compound eyes mounted on movable eye stalks, lens has 14,000 receptors

47. More Malacostraca
Krill (Euphausiacea)- make up a large portion of food chain in ocean, huge population collapse 1990’s, now regulated
Isopoda (pill bugs)- live under rocks, roll up in ball when disturbed, some deepwater species grow quite large
Amphipoda (beach Hopper)- live in seaweed at high tide line beach.

48. Krill (Euphausiacea)

49. Isopods

50. Amphipoda (beach Hopper)

51. Brachiopoda and Maxillopoda
Brachiopoda- fairy shrimp, Brine shrimp- marine and short lived, eggs can withstand drying and hatch when wet again Water fleas (Daphnia)- fresh water ponds, swim with antennae
Maxillopoda –Copepods, mostly planktonic filter feeders, basis of many food webs Barnacles- sessile, attach themselves to substrate, rocks, ships, whales, docks

52. Brine Shrimp