Phylum Arthropoda

1. Phylum Arthropoda

2. Phylum Arthropoda Facts • Arthropods inhabit virtually every environment on earth • Includes: • Crayfish • Lobsters • Spiders • Scorpions • Insects • Considered to be the most successful animal group • More than 1 million known species (6-9 million est.)

3. Phylum Arthropoda Characteristics • Microscopic to 12 ft length (King Crab) • Jointed appendages- Structures extending from body wall • Bilaterally symmetrical • Evolutionary links to annelids • Many are toxic • Many vector (transmit) pathogens • Many beneficial

4. Phylum Arthropoda • Rigid exoskeleton for support and protection • Molting occurs during growth • Paired, jointed appendages • Ventral nervous system (ventral nerve cord) • Reduced coelom • Open circulatory system • Complete digestive tract • Malpighian tubules- Excretory units • Respiration through tracheae (network of fine tubes) and spiracles (structures where air enters) • Metamorphosis often occurs during development

5. Arthropod Metamorphosis • Metamorphosis = radical change in body form • Complete Metamorphosis- Includes pupa stage • Incomplete metamorphosis- No pupa stage • Results in reduced competition between immature forms and adults • Eat different food • Occupy different habitats • Example = caterpillar vs. butterfly

6. Metamorphosis

7. Arthropod Exoskeleton • Secreted by the epidermis • Functions: • Support http://www.youtube.com/watch?v=zXhdr0TpOwYBack to results • Protection • Prevent water loss • Muscle attachment/movement • Two layers • Epicuticle (outside) = waxy, impermeable to water • Procuticle = chitin • Must be shed to allow growth (molt)

8. Subphylum Trilobitomorpha • Trilobites inhabited Earth’s oceans from • 600 mya – 345 mya – are now extinct • Body oval & flattened _ divided into three segments (longitudinal) • Rolled into a ball for protection

9. Phylum Arthropoda- Living Subphyla: • Hexapoda: • Class Insecta • Myriapoda: • Class Diploda • Class Chilopoda • Crustacea: • Class Remipedia • Class Cephalocarida • Class Branchiopoda • Class Malacostraca (Orders Decapoda and Isopoda) • Class Maxillopoda • Chelicerata: • Class Arachnida (Orders Scorpions, Acari, and Araneae) • Class Merostomata • Class Pycnogonida

10. Phylum Arthropoda • 2 minor classes: • Class Merostomata- Horseshoe crabs • Class Pycnogonida- Sea spiders • 5 major classes: • Chilopoda – centipedes • Diplopoda – millipedes • Malacotsraca – crabs, lobster, crayfish,shrimp • Insecta – insects • Arachnida – spiders, scorpions, mites, chiggers

11. Classification of Arthropods • Centipedes – 1 pr legs/segment • Millipedes – 2 prs legs/segment • Insects – 3 pairs of legs • Arachnids – 4 pairs of legs • Crustaceans – 5 pairs of legs

12. Subphylum Myriapoda- Class Chilopoda • Centipedes • 100 leggers • Flattened worm like w/1 pr legs/seg • Carnivores • Possess a pair of poison claws or legs just behind the head which are used to paralyze their prey • Feed on insects or small animals • Most centipedes are beneficial • Large species found in the tropics (length of up to 18 inches) • Can inflict painful bites

13. Subphylum Myriapoda- Class Chilopoda

14. Subphylum Myriapoda- Class Diplopoda • 1000 leggers • Cylindrical worm like with 2/prs legs/seg • Decomposers or herbivores • >1000 species in US • Short antenna • Non-toxic

15. Subphylum Myriapoda- Class Diplopoda

16. Subphylum Myriapoda- Millipedes and Centipedes • Life Cycle • Millipede eggs are deposited in masses in the soil. • Young millipedes have fewer segments than the adult, but they add segments at each molt of the outer shell, or exoskeleton. • Molting occurs 7-10 times before maturity. • Young millipedes mature the second year after hatching. • Some species may live for several years. • Similarly, centipedes molt several times, adding legs and body segments with each molt

17. Subphylum Crustacea • Body segmented with hardened Limbs • Limbs generally with two branches • Two pairs of antennae • Two compound eyes (eyes with many lenses) • Body with 7 or more pairs of sometimes very different appendages for feeding, locomotion and sex • Respiration by gills • Nauplius- Distinctive larval stage with three pairs of branched appendages • Although originally aquatic, many crustaceans are adapted to life on land

18. Subphylum Crustacea • Shrimp • Lobster • Krill • Pill bug • Crabs • Crayfish • Barnacles (sessile)

19. Subphylum Crustacea- Class Remipedia • Cave-dwelling • 30 segments with uniform, biramous appendages • Carribean, Indian Ocean, Canary Islands, Australia

20. Subphylum Crustacea http://www.youtube.com/watch?v=eKPrGxB1Kzc

21. Subphylum Crustacea- Class Branchiopoda • Freshwater mostly • Leaflike appendages for respiration, filter feeding and locomotion • Fairy, brine and clam shrimp and water fleas

22. Subphylum Crustacea- Class Maxillopoda • Five head, six thoracic, and four abdominal somites with a telson • Variously fused segments • No appendages on reduced abdomen • Barnacles and copepods

23. Subphylum Crustacea- Class Malacostraca • Modified appendages for crawling, feeding or swimming • Lobsters, crayfish, crabs, shrimp, and isopods

24. Subphylum Hexapoda- Class Insecta • >750,000 species • Upwards of 3 million species • Outnumber all other plant and animal groups • Found in all environments • 10,000 ft. high • Some fly 100s of KM per week

25. Subphylum Hexapoda- Class Insecta • Three body divisions • Head • Thorax • Abdomen • Exoskeleton • 12 Inches—Largest • 1MM-Smallest • Rapid growth rate • Exponential • Most mature < 1 year • Display almost every color

26. Subphylum Hexapoda- Class Insecta • Open circulatory system • Spiracles along abdomen used for breathing • Highly modified mouth parts (mandibles) • Some beetles can chew through lead or zinc • Well developed tube within a tube digestive system • Well developed nervous system • Sight- two types of eyes • Smell/taste-Use of antennae and feet • Hearing- tympanum (eardrum)

27. Subphylum Hexapoda- Class Insecta • Pheromones- External hormones used for communication (especially in finding mates)

28. Subphylum Hexapoda- Class Insecta • >390 million years old • Coevolved with plants (Especially flowering plants) • 1st insects were flightless

29. Subphylum Hexapoda- Class Insecta • Entomology- Study of insects and other arthropods • Helpful or harmful • Helpful insects: • Pollinators • Research and discovery- fruit fly for genetic research • Food producers- honey • Textiles- Silk & beeswax • Biological control agents

30. Subphylum Hexapoda- Class Insecta • Harmful insects: • Disease vectors • Crop/food destruction • Textile destruction

31. Subphylum Hexapoda- Class Insecta Morphology • Mimicry- Resemble something you are not in order to survive • Protective resemblance

32. Subphylum Hexapoda- Class Insecta Hierarchy • Ants, termites, hornets, wasps, and some bees • Social hierarchy • Caste system • King and queen • Large number of individuals function as one unit • Division of labor • Physical appearance of individuals depends on their caste placement

33. Subphylum Hexapoda- Class Insecta Hierarchy

34. Subphylum Chelicerata- Class Arachnida • Spiders • Mites/ticks • Scorpions

35. Most familiar spiders Cephalothorax (head fused to thorax)and abdomen All toxic No antennae Use pedipalps ( 2nd pair of appendages modified to catch and handle prey) and walking legs as sensory organs >30,000 Species/3,000 in U.S. Tarantulas largest Body 2.5 in, legs 9-10 in. Many, but not all spiders web builders Spinneretes- Appendages that secrete silk) Liquid feeders Inject digestive enzymes into prey and drink juices Use powerful jaws to crush exoskeleton- then digest and eat Subphylum Chelicerata- Order Araneae

36. Subphylum Chelicerata- Class ArachnidaOrder - Araneae http://www.asterpix.com/console/?avi=10313601

37. Subphylum Chelicerata- Class Arachnida • Order Scorpions • Tropical and subtropical • 0.5 to 8 IN. • Stinger on end of tail • Pedipalps are pinchers • Nocturnal • Can be deadly but many aren’t • One of the oldest forms of life on Earth

38. Other Arachnids • Order Acari • Ticks, mites, and chiggers • Found everywhere • Omnivorous/scavengers/parasites • Many blood feeders • Disease vectors • Rocky Mountain Spotted Fever • Lyme Disease

39. Other Chelicerates • Class Merostomata- • Subclass Xiphosura- Horseshoe crabs (Limulus) • Marine with book gills • Not actually crabs • Shallow water on Atlantic coast • Feed on worms, bivalves, and small animals • Subclass Eurypterida- Extinct giant water scorpions • Class Pycnogonida- Sea spiders • Reduced abdomen • No special respiratory/excretory organs • Four to six pairs of legs

40. Class Merostomata

41. Class Pycnogonida