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ecdysozoa iI

ecdysozoa iI. BIOL240.002 Zoology 27 October 2014. Phylum Arthropoda “joint foot” —~1,000,000 (915,047) spp. arthropods. Metameres grouped into tagmata Head, thorax, abdomen Cephalothorax, abdomen Head, trunk Appendages specialized for various tasks

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ecdysozoa iI

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  1. ecdysozoaiI BIOL240.002 Zoology 27 October 2014

  2. Phylum Arthropoda“joint foot”—~1,000,000 (915,047) spp. arthropods • Metameres grouped into tagmata • Head, thorax, abdomen • Cephalothorax, abdomen • Head, trunk • Appendages specialized for various tasks • Hypodermis secretes cuticle of chitin • Thinner at joints • Almost all dioecious • Copulate or transfer spermatophores Fig. 13.2 p. 247 Fig. 13.3 p. 248

  3. Arthropod Internal Anatomy • Dorsal brain, ventral nerve cord with ganglia in each segment • Very reduced true coelom • Gills in aquatic spp. • Open circulatory system • Heart with pair of ostia per segment • Coxal glands and/or Malpighian tubules • Latter excrete uric acid in terrestrial spp. • Tracheal system and spiracles in terrestrial spp. • Or book lungs Fig. 13.7 p. 251 Fig. 13.22 p. 260 Fig. 13.39 p. 270

  4. Insect Tracheal System Fig. 13.45 p. 272

  5. The Compound Eye of Arthropods Fig. 13.23 p. 261

  6. Arthropod Diversity Fig. 13.34 p. 267

  7. Arthropod Systematics and Taxonomy 15,781 spp. 4 classes 23 orders 64,878 spp. 3 classes 19 orders 36,544 spp. 3 classes 48 orders 797,844 spp. 2 classes 33 orders Fig. 13.4 p. 249

  8. SubphylumMyriapoda Fig. 13.4 p. 249

  9. Class Chilopoda—centipedes“lip foot” • 3146 spp. in 5 orders • Simple eyes • Mandibles and 2 prs. of maxillae • First trunk segment bears venomous maxillipeds • 15-170 prs. of legs • Long, for speed • Active predators • Spermatophore transfer • Some spp. brood • Juveniles typically have reduced number of legs Fig. 13.15 p. 256

  10. Class Diplopoda—millipedes“double foot” • 12,144 spp. in 16 orders • Simple eyes • Mandibles and 1 pr. of maxillae • Up to 100 diplosegments have two prs. of legs, 2 prs. of heart ostia, 2 ventral nerve ganglia, 2 prs. of spiracles • Short legs • Herbivores and scavengers • Copulate and brood eggs • Juveniles hatch with three prs. of legs Fig. 13.16 p. 256

  11. Class Pauropoda—pauropods“small foot” • 416 spp. in 2 orders • Very small (<1.5 mm) • Most spp. have lost heart and tracheal system • Scavengers • Biramous antennae • Eyes lost • Mandibles and 1 pr. of maxillae • 9-11 prs. of legs on trunk double segments • Sister taxon: Diplopoda • Spermatophores • Juveniles hatch with 3 prs. of legs, adding legs with each molt

  12. Class Symphyla—symphylans or garden“together tribe” centipedes • 75 spp. (orders unsettled) • Pigmentless, eyeless herbivores and detritus feeders • Small (<8 mm) • Mandibles and 2 prs. of maxillae • Eyes lost • 10-12 prs. of legs on 15-24 trunk segments • Sister taxon: Chilopoda • Spiracles on sides of head only • Spermatophores deposited by ♂ picked up in mouth of ♀ and used to fertilize ova she plucks from her reproductive tract • Juveniles hatch with 6 prs. of legs, adding legs with each molt

  13. SubphylumChelicerata Fig. 13.4 p. 249

  14. Class Merostomata—horseshoe crabs“thigh mouth” • 4 marine spp. in 1 order • Chelate appendages: • Chelicerae flank mouth • Pedipalps • Four pairs of legs • Abdominal appendages modified as 1 pair of genital opercula and 5 pairs of book gills • Telson used in righting • Coxal glands (last pr. of legs) • Beach spawners with egg capsules Fig. 13.5 p. 250

  15. Class Pycnogonida—sea spiders“compact knee” • 1265 marine spp. (orders unsettled—so, 1?) • Elongate proboscis with mouth on end • Flanking chelicerae • Pedipalps • 8 legs • External fertilization • Males of some spp. carry eggs on ovigers • Protonymphon larval stage has 3 prs. of legs Fig. 13.6 p. 251

  16. Class Arachnida—arachnids“spider” • …but also scorpions, pseudoscorpions, daddy longlegs, ticks, mites, etc. • 63,609 spp. in 18 orders • Chelicerae: • Venomous fangs in spiders • Rarely fatal to humans • Pedipalps: • Used by male spiders for spermatophoretransfer • Pincers in scorpions and pseudoscorpions • Former have venomous stinger • 25 spp. can be deadly to humans • 8 legs • Pedicel: Cephalothorax/abdomen constriction in spiders • Absent in daddy longlegs • Capitulum: head projection with mouthparts of ticks and mites Fig. 13.8 p. 252 Fig. 13.7 p. 251 Fig. 13.13 p. 254 Fig. 13.14 p. 254

  17. Arachnid Silk • Spiders, mostly • Also pseudoscorpions, mites • (As well as certain insects and myriapods) • Abdominal glands that open via spinnerets • Elastic protein with high tensile strength • Webs • Prey wrapping • Draglines • Sperm webs for spermatophores on the pedipalps • Egg cases • Balloons for dispersal

  18. SubphylumCrustacea Fig. 13.4 p. 249

  19. Class Branchiopoda—fairy, brine, tadpole, and“gill foot” clam shrimp; water fleas • 1363 spp. in 3 orders • Legs double as respiratory surfaces • Often with a carapace covering the body • Water fleas are dominant zooplankton in freshwater habitats Fig. 13.25 p. 262

  20. Class Maxillopoda—ostracods, copepods, fish“jawbone foot” lice, tongue worms, and barnacles • 6970 spp. in 29 orders • Up to 5 cephalic, 6 thoracic, and 4 abdominal segments • Copepods and ostracodsare dominant zooplankton in freshwater habitats • Tongue worm lung parasites formerly a phylum (Pentastomida) • Barnacles: calcareous plates surround sessile adults • Antennae modified as cement glands • Curled thoracic cirripedia with setae capture food • Simultaneous hermaphrodites Fig. 13.25 p. 262 Fig. 13.26 p. 263 Fig. 13.27 p. 264

  21. Class Malacostraca—shrimp, crayfish, lobster, “soft shell”crabs, krill, scuds, pillbugs • 28,199 spp. in 15 orders • Marine, freshwater, and terrestrial • Cephalothorax and abdomen • Typically 8 thoracic segments, 6 abdominal segments • Chelae: thoracic pincers of crabs, crayfish, and lobsters • Crabs: abdomen reduced and folded under Fig. 13.32 p. 265 Fig. 13.31 p. 265 Fig. 13.28 p. 264 Fig. 13.30 p. 265

  22. SubphylumHexapoda Fig. 13.4 p. 249

  23. Hexapod Systematics and Taxonomy Fig. 13.33 p. 266

  24. Class Entognatha—entognaths“inside jaw” • 2841 spp. in 3 orders • Coneheads, springtails, and bristletails • Small size (<10 mm, most <5 mm) • Tips of mandibles and maxillae extend from gnathal pouch • Antennae have musculature in every segment • Wingless (not lost, though) • Many eyeless Fig. 13.33 p. 266

  25. Class Insecta—insects“cut into” • 795,003 spp. in 30 orders • Mostly terrestrial and aquatic, few marine • 2 prs. of ectognathous mouthparts • Mandibles • Maxillae • Single labrum above • Single labium below • Antennae have musculature in two basal segments only • Most have 2 prs. of wings • Meso- and metathoracic • Cuticular outgrowths Fig. 13.35 p. 267 Fig. 13.44 p. 272

  26. Insect Metamorphosis Fig. 13.60 p. 282 • Direct development in primitive wingless spp. (e.g., silverfish) • Winged insects have larvae with instars • Divided by molts • Hemimetabolousor incomplete metamorphosis • Nymph or naiad instars gradually develop wings • Holometabolousor complete metamorphosis • Larva  Pupa  Adult • Predominant pattern in class Fig. 13.48 p. 275 Fig. 13.47 p. 274

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