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http://i.livescience.com/images/080125-horseshoe-crab-02.jpg. Phylum Arthropoda. http://www.andrill.org/iceberg/blogs/julian/images/pc030012sea-spider.jpg. http://thedailydish.files.wordpress.com/2009/02/lobster.jpg.
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http://i.livescience.com/images/080125-horseshoe-crab-02.jpg Phylum Arthropoda http://www.andrill.org/iceberg/blogs/julian/images/pc030012sea-spider.jpg http://thedailydish.files.wordpress.com/2009/02/lobster.jpg
Known for metamerism (body divided into segments)- each body region = tagmata • External jointed skeleton (exoskeleton) with 2 layers: • Epicuticle= Outermost waxy layer • Procuticle= Inner layer made of chitin which partially hardens • Exoskeleton molts (endysis) periodically so that arthropod can grow. • Internal cavity (hemocoel) with open circulatory system and internal organs • Metamorphosis (change in body form/physiology) often present; this reduces competition between larva and adult stages
Subphylum Chelicerata • Known for 2 tagmata: • Prosoma/cephalothorax = 1st body region which is a sensory, feeding, and locomotortagmata. ***This region also includes legs (appendages). 1st pair of appendages are called chelicerae (used for feeding); 2nd pair are called pedipalps (used for used in feeding, locomotion, or reproduction) • Opisthosoma = 2nd body region which contains digestive, reproductive, excretory, and respiratory organs • Mostly carnivores • No antennae
Class Merostomata • Horseshoe crabs (only 4 species living) • Mostly in Atlantic Ocean and Gulf of Mexico • Scavenge for annelids, molluscs, and other invertebrates • Last pair of appendages have leaflike plates for locomotion and digging • Opisthosoma contains book gills (gases exchange between blood and water) • Dioecious (female lays eggs which are fertilized by male)
Class Arachnida • Malpighian tubules for excreting waste • Book lungs (similar to book gills) • Open circulatory system • Many sensory structures (sensilla) on body • Dioecious (often by spermatophore) • Most are oviparous (female lays eggs that develop outside body) • Others may be ovoviviparous (development internal with a yolky egg for nourishment) or viviparous (eggs that are nourished directly by female mother, live young are born) • Many care/tend to eggs and young • Digestion may be partially external as well as internal
Class Arachnida(cont.) • Order Scorpionida • Scorpions • Dancing-like courtship that is followed by ovoviparous or viviparous fetilization (young stay with mother on her back until 1st molt) • Order Araneae • Largest order: Spiders • Prosoma with poison glands and fangs • Pedipalps modified for sperm transfer • 6-8 eyes (some species have well developed eyes for catching prey)
World’s Most Venomous Scorpions… *In general, scorpions with slim and narrow pincers are equipped with more toxic venom. Powerful venom compensates for the scorpion’s weaker pincers and lack of brawny strength. DEATH STALKER SCORPION http://1.bp.blogspot.com/_6EdUefA9bik/RsDNm0QzzfI/AAAAAAAAA7o/O2b4TnAa9ZE/s400/death-stalker-scorpion.jpg http://www.orovalleyhomes4sale.com/images/ScorpionsInDark.jpg Scorpions glow under UV light (black light) http://www.dkimages.com/discover/previews/797/931243.JPG
Opisthosoma has spinnerets associated with silk glands (there are several types of silk produced) • Silk may also be used by young spiders for dispersal (called ballooning) • Female may attract male with pheromones or male may attract female by plucking on her web • Sperm given to female with pedipalps, female lays up to 3,000 eggs in silk case • Order Opiliones • Harvestmen or daddy longlegs • Prosoma and opisthosoma are joined (making body look oval/ovoid) • Many are omnivores (feed on plants and animals) • Sperm transfer is direct by penis like structure
World’s Most Venomous Spiders… http://farm3.static.flickr.com/2173/2158857410_d57efe2160.jpg http://www.spiderzrule.com/spider307/PICT0645.JPG The Brazilian Wandering Spider (Guinness World Records 2007) http://www.spiderzrule.com/spiders063/Picture%20029.jpg
Australian Funnel-web Spider http://mentalfloss.cachefly.net/wp-content/uploads/2008/11/440atraxspider.jpg http://abcnews.go.com/images/GMA/nm_SydneyFunnelWebSpider_090608_mn.jpg http://australianmuseum.net.au/Uploads/Images/9618/dang_29_big.jpg
Order Acarina • Mites and Ticks (mostly “ectoparasites”) • Prosoma and opisthisoma are fused • Capitulum projects from anterior carrying mouthparts • Chelicerae and pedipalps modified for piercing, biting, anchoring, and sucking. • Do not permanently attach to host (parasite???) • Some carry diseases (Lyme Disease; Rocky Mountian Spotted Fever) • Class Pycnogonida • Sea spiders (marine, located on ocean floor)
Mites vs. Ticks http://axiom.anu.edu.au/~luke/images/mites/dust_mites_pin.jpg http://academics.hamilton.edu/biology/kbart/image/Wood%20Tick.jpg Mite Tick
http://www.lymediseaseaction.org.uk/images/i03/rostrum.jpg http://www.regionalpestmanagement.com/images/tickmaster.jpg
Subphylum Crustacea • Almost all aquatic • 2 pairs of antennae • Biramous appendages (appendages separate into 2 parts at distal end- making “Y” shape) • 5 classes (3 common)
Class Malacostrata • Largest class of crustaceans • Includes shrimp, crabs, lobster, crayfish, mysids, krill, isopods, and amphipods • Feed on other invertebrates, plant matter, and dead/decaying animals • Sensory structures = Compound eyes, simple eyes, statocysts, chemoreceptors, proprioceptors, and tactile setae. • Excretory organs (green glands) are at bases of second antennae • Dioecious (most young hatch as mini adults) • Most larvae planktonic (with a single median photoreceptor)
Appendages (of most crustaceans): • Pairs 1-2 = Antennae • Pairs 3-5 = Associated with mouth • 3 = Mandibles (chewing/grinding) • 4-5 = Maxillae (food handling; #4 has a gill) • Pairs 6-8 = Maxillipeds (sensory and food handling) • #7-8 have gills • Pairs 9-13 = Pereopods (mainly for walking; contains gonads) • 9 = cheliped (pincher to capture food) • All but last pair after perepods = Pleopods(swimmerets) • Last segment (flipper)= Telson(anus) which has appendages called uropods
Class Branchiopoda • Fairy shrimp, brine shrimp, water fleas • resistant embryos are found in this group because they usually live in temporary ponds, salty environment, or need to survive over winter • Class Maxillopoda • 2 common groups: copepods and barnacles • Most copepods planktonic with median ocellus and very important to marine food webs • Most barnacles are monoecious • Barnacles attach to a variety of substrates (sometimes by a stalk) and some are modified parasites
Subphylum Myriapoda • “Myriad” = ten thousand • 2 tagmata (head and trunk) • 4 classes (2 common) • Class Diplopoda= millipedes • 11-100 trunk segments • Round in cross section • Food = decaying plant matter • Roll into a ball or release hydrogen cyanide when threatened • 2 pairs of legs per segment
Class Chilopoda = centipedes • Nocturnal • Flat in cross section • Carnivores (arthropodss, worms, snails, frogs) • Poison claws to kill/immobilize prey • One pair of legs/segment http://shimmyshewobble.com/wp-content/uploads/2009/05/giant_centipede.jpg http://www.life.illinois.edu/ib/109/Insect%20rearing/photos/millipede.jpg
Subphylum Hexapoda • “Hexa” = six (3 pairs of legs?) • Mouthparts project from head • Most have wings capable of flight • Most have 1 pair of antennae • 3 tagmata: head, thorax, and abdomen • Brain = ganglion (some capable of learning/memory) • Compound eyes (as well as other sensory structures) • Molting with metamorphosis • Tracheal system for gas exchange • Blood is not used for gas transport! • Complex mating behaviors= high reproductive potential • Some insects are social