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arthropods

09 June 2011. Arthropoda.ppt. 2. Phylum Arthropoda. Phylum Arthropoda Greek: arthro = jointed, pod = foot Huge group, > 1,000,000 species.estimate: 1,000,000 spp. arthropods 1,190,000 spp. animals ~ 84% of all animal species are arthropods!! . 09 June 2011. Arthropoda.ppt. 3. Phylum Arthropoda .

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arthropods

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    1. 09 June 2011 Arthropoda.ppt 1 ARTHROPODS Phylum Arthropoda

    2. 09 June 2011 Arthropoda.ppt 2

    3. 09 June 2011 Arthropoda.ppt 3 Phylum Arthropoda Body pla n Tube-in-tube, bilateral symmetry, protostomous, split coelom Marine, aquatic, terrestrial even Antarctica ! Cell and tissue organization Triploblastic, complex organs ~ 30,000 genes in genome, (same as for mammals)

    4. 09 June 2011 Arthropoda.ppt 4 Phylum Arthropoda Unique, distinguishing characters Huge group, > 1,000,000 species. How can we explain the success of the arthropods? Exoskeleton!

    5. 09 June 2011 Arthropoda.ppt 5 Phylum Arthropoda Exoskeleton of chitin and protein (= cuticle) structure: epicuticle (oily, waxy) exocuticle (chitin & protein) endocuticle (chitin only) epidermis secretes cuticle

    6. 09 June 2011 Arthropoda.ppt 6 Problems associated with exoskeleton. Problem 1. MOVEMENT Solution: Joints in exoskeleton. arthro-, = joint -pod, = leg, foot Exocuticle absent from joints; may form hinges. Endocuticle alone allows flexibility.

    7. 09 June 2011 Arthropoda.ppt 7 Problems associated with exoskeleton. Problem 2. GROWTH Solution: Molting

    8. 09 June 2011 Arthropoda.ppt 8 Molting (1) Secretion of "molting fluid" to dissolve old endocuticle.

    9. 09 June 2011 Arthropoda.ppt 9 Molting (2) New cuticle formed under old exocuticle. Break out of old cuticle Old cuticle breaks at line of weakness

    10. 09 June 2011 Arthropoda.ppt 10 Molting (3) Inflate with water/air to increase size while skeleton soft, but soft skeleton & gravity limit size; arthropods are mostly small. Hardening of new exocuticle.

    11. 09 June 2011 Arthropoda.ppt 11 Growth stages Arthropod passes thru 3-20+ growth stages in life cycle. Some stop molting as adults (insects, most spiders) Some continue to molt (crayfish, tarantulas)

    12. 09 June 2011 Arthropoda.ppt 12 Problems associated with exoskeleton. Problem 3. SENSORY INPUT touch sensory setae connected to neurons smell & taste hollow sensory setae w/ chemosensitive nerve endings

    13. 09 June 2011 Arthropoda.ppt 13 Problems associated with exoskeleton. Problem 3. SENSORY INPUT vision clear cuticle over compound or simple eyes

    14. 09 June 2011 Arthropoda.ppt 14 Problems associated with exoskeleton. Problem 3. SENSORY INPUT hearing tympanum = endocuticle, vibrates like eardrum trichobothria (right ?)

    15. 09 June 2011 Arthropoda.ppt 15 Benefits of Exoskeleton: to individuals: Support Locomotion lever system walk, swim, fly Mechanical protection (armor) Retards evaporation (in air) and/or osmosis (in water) water balance.

    16. 09 June 2011 Arthropoda.ppt 16 Benefits of Exoskeleton: to the phylum: Reduction of coelom & segmentation Abandoned hydrostatic system of annelid-like ancestor) Coelom reduced to pericardial cavity Segments fused = tagma, tagmata Tagmosis Specialization of body regions (= tagmata) Specialization of appendages

    17. 09 June 2011 Arthropoda.ppt 17 Tagmosis Head (~ 4-6 segments) feeding, sensation Head appendages mandibles, maxillae, maxillipeds, chelicerae antennae

    18. 09 June 2011 Arthropoda.ppt 18 Tagmosis Thorax (~ 3-6 segments) locomotion, grasping. Thoracic appendages walking legs, wings chelipeds

    19. 09 June 2011 Arthropoda.ppt 19 Tagmosis Abdomen (~8- 30+ segments) respiration, reproduction, etc. Abdominal appendages abdominal gills (aquatic insect larvae) swimmerets (crayfish) filtering legs (barnacles) gonopods (crayfish, etc.) spinnerets (spiders)

    20. 09 June 2011 Arthropoda.ppt 20 Tagmosis Number of segments/legs in each tagma varies by subphylum, class. Cephalothorax of 6 segments in Chelicerata 1 pr. chelicerae 1 pr. pedipalps 4 pr. walking legs Cephalothorax of 13 segments in Crustacea (shrimps) 2 pr. antennae 1 pr. mandibles 2 pr. maxillae 3 pr. maxillipeds 5 pr. walking legs (1st pair modified as chelipeds)

    21. 09 June 2011 Arthropoda.ppt 21 Phylum Arthropoda Ways the needs of cells are met 1. Food Herbivores, predators, detritivores, parasites, filter feeders, . . . 2. O2 and CO2 exchange Gillsusu. modified legs, Book lungs, Tracheal systems 3. Waste removal Diffusion from gills, Malphigian tubules

    22. 09 June 2011 Arthropoda.ppt 22 Other arthropod characters Open circulatory system Dorsal heart pumps hemolymph over brain Hemolymph moves through hemocoel back toward heart Ostia (holes) in sides of heart let hemolymph in to go around again.

    23. 09 June 2011 Arthropoda.ppt 23 Other arthropod characters Respiratory systems Gills in aquatic/marine arthropods Tracheal systems in most terrestrial arthropods Book lungs (modified gills) in spiders & scorpions

    24. 09 June 2011 Arthropoda.ppt 24 Phylum Arthropoda Special concerns of a multicellular animal Circulation: Open circulatory system, Coordination, Structural support, Movement, Maintenance of homeostasiswater balance.

    25. Phylum Arthropoda Special concerns of a multicellular animal Circulation: Open circulatory system, (analogous to that in Mollusca) Dorsal aorta Hemocoel Pores (ostia) valved Text fig. 42.3 09 June 2011 Arthropoda.ppt 25

    26. 09 June 2011 Arthropoda.ppt 26 Other arthropod characters Nervous system resembles that of annelid Dorsal brain with nerves around esophagus Paired ventral nerve cords Segmental ganglia Often fused into 1-2 ganglia in each tagma

    27. 09 June 2011 Arthropoda.ppt 27 Phylum Arthropoda Special concerns of a multicellular animal Exoskeleton for Structural support, Movement, Maintenance of homeostasiswater balance Malphigian tubules, etc. Reproduction Usually sexual, some parthenogenic

    28. 09 June 2011 Arthropoda.ppt 28 Distinguishing Characters of Arthropoda Jointed exoskeleton Tagmosis Compound eyes

    29. 09 June 2011 Arthropoda.ppt 29 Classification of Arthropoda Subphylum Trilobita Subphylum Crustacea Subphylum Cheliceriformes Subphylum Myriopoda Subphylum Hexapoda

    30. 09 June 2011 Arthropoda.ppt 30 Classification of Arthropoda Subphylum Trilobita Class Trilobita Three-lobed head & body (left, middle, right) Diverse in Paleozoic ~540-240 MYA Extinct

    31. 09 June 2011 Arthropoda.ppt 31 Classification of Arthropoda Subphylum Crustacea 2 pr. Antennae (antennules, antennae) Cephalothorax 13 segments & appendage pairs Abdomen variable among Classes

    32. 09 June 2011 Arthropoda.ppt 32 Classification of Arthropoda Subphylum Crustacea Class crabs Class barnacles

    33. 09 June 2011 Arthropoda.ppt 33 Classification of Arthropoda Subphylum Chelicerata Cephalothorax Jaws are chelicerae Pedipalps 4 pr. Walking legs Abdomen

    34. 09 June 2011 Arthropoda.ppt 34 Classification of Arthropoda Subphylum Chelicerata Class Horseshoe crabs Horseshoe crabs Scorpions ??

    35. 09 June 2011 Arthropoda.ppt 35 Classification of Arthropoda Subphylum Chelicerata Class Arachnids Lost compound eyes Spiders Daddy-long-legs vinegaroons mites & ticks more Scorpions ??

    36. 09 June 2011 Arthropoda.ppt 36 Classification of Arthropoda Subphylum Myriapoda Legs unbranched Head & body Class Centipedes 1st legs are fangs

    37. 09 June 2011 Arthropoda.ppt 37 Classification of Arthropoda Subphylum Myriapoda Class Millipedes Double segments (2 pr. legs per segment)

    38. 09 June 2011 Arthropoda.ppt 38 Classification of Arthropoda Subphylum Hexapoda Class Insects Head, thorax, abdomen 2 pr. Wings ~800,000 species, majority of all arthropods

    39. 09 June 2011 Arthropoda.ppt 39 Classification of Arthropoda Subphylum Hexapoda Class Insects Incomplete metamorphosis Dragonflies Orthoptera Hemiptera, Homoptera Complete metamorphosis Coleoptera (beetles) Hymenoptera (wasps, ants, bees) Diptera (flies)

    40. 09 June 2011 Arthropoda.ppt 40 Why are Arthropods so successful? Exoskeleton ? tagmosis ? evolution of flight ? speciation ? 106 species of insects.

    41. 09 June 2011 Arthropoda.ppt 41 Why are Arthropods so successful? Exoskeleton ? protection from water loss ? early colonization of land ? head start. Arthropods were diverse and widespread on land before vertebrates!

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