Arthropods Tang Hiu Man(22) 6S Arthropods Tang Hiu Man (22) 6S

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<ul><li><p>Arthropods</p><p>Tang Hiu Man(22) 6SArthropodsTang Hiu Man (22) 6S</p></li><li><p>IntroductionAnarthropodis aninvertebrateanimalhaving anexoskeleton(externalskeleton), a segmented body, and jointedappendages Largest group of invertebrate(1 million species)Occupy 80% of all the animal speciesLargest number of speciesHas individuals occupying the greatest variety of habitatsconsists of repeatedsegments, each with a pair ofappendages</p></li><li><p>FeaturesAll consists of chitinous() exoskeleton (cuticle) and jointed legs, some may have wings (eg. Butterflies, dragonflies)Consists of repeated segments, each with a pair of appendagesInternal organs are also built of repeated segmentsHighly versatile (enabled them to become the most species-rich animals in most environment )vision relies on various combinations ofcompound eyes</p></li><li><p>1.Crustaceans()Have biramous()appendages </p><p> Shrimp crabBarnacle water flea </p></li><li><p>2.Myriapods()have many body segments, each bearing one or two pairs of legs. </p><p> centipede millipede</p></li><li><p>3.Arachnids()presence ofchelicerae(), appendages just above / in front of the mouth. spider mite scorpion</p></li><li><p>4.Insectswith six thoracic legs </p><p>Butterfly bee beetledragonfly</p></li><li><p>Cuticle (chitinous exoskeleton)Reduce water lost by evaporationAct as a protective layer against bacterial invasion &amp; mechanical injuryProvide a rigid framework to support the body on landThe presence of joints between segments of legs allow rapid locomotion to take placeProvide large surface area for muscle attachment that produces force for locomotionThe thoracic() cuticle with wings to make flight possibleWith colour for camouflage()</p></li><li><p>WingsThey enable insects to fly so that:</p><p>Insects can get their food &amp; escape from their enemies quickly, thus flight facilitates survival.Insects can disperse themselves &amp; thus reduce the problem of overcrowding. </p></li><li><p>Jointed LegsAllow walkingA pair of strong &amp; muscular hind legs() allow rapid hopping() for long distance during escaping from enemies or catching preys</p></li><li><p>Small sizeReduce the competition for food &amp; spaceReduce body weight to facilitate flightInsects can easily hide themselves in crevices()</p></li><li><p>Recent News </p><p>http://www.babynet.com.hk/content/%E5%90%83%E8%9F%B2%E6%95%91%E5%9C%B0%E7%90%83-%E5%A4%A7%E5%AE%B6%E9%83%BD%E4%BE%86%E5%90%83%E8%9F%B2%E6%95%91%E5%9C%B0%E7%90%83%E5%9C%96%E7%89%87 </p></li><li><p>Modification of Jointed AppendagesJointed appendages can be modified Can become many different structures for different functionseg. appendages on head antennae(), palps() for sensory functionsAppendages on thorax &amp; abdomen() walking, swimming, transferring sperms</p></li><li><p>Gill</p><p>Book lungTracheal system</p></li><li><p>Reproductionterrestrial: internal fertilizationAquatic : external fertilization except scorpion (lay eggs)</p><p>A few:have organs of both sexes (eg. barnacles)Parthenogenesis()(reversible)</p></li><li><p>Referencehttp://en.wikipedia.org/wiki/Arthropod#Reproduction_and_development http://www.google.com.hk/images Advanced-level Biology for Hong KongAL Biology Book 3 Ecology </p></li><li><p>~The End~</p></li></ul>