Jan 25 - Biol 119

Jan 25 - Biol 119 - 1/26/2012 Announcements Quiz will open...

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1/26/2012 1 Invertebrates & Chordates Announcements Quiz will open online Thursday @1pm, close Friday @ 12noon PRS “problems” Phylum Arthropoda the real rulers of the earth Diversity of arthropods is unmatched by any other group (make up 95% of known animal sp.) Evolution of Segmented Body Plan Early arthropods (eg. trilobites) showed little variation from segment to segment As arthropods evolved, segments fused, & appendages became more specialized Appendages of some living arthropods are modified for many different functions Key Innovations of Arthropod Body Plan Exoskeleton Jointed limbs Segmented body Head (strong cephalization) Thorax ( jointed limbs & wings attachments) Abdomen Exoskeleton advantages & challenges ADVANTAGES: a protective feature important for attachment of muscles rapid movement and precise control over their movement CHALLENGES: Growth = molting Loss of protection Energetically costly
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1/26/2012 2 How did an exoskeleton help in the move to a terrestrial environment (over evolutionary time)? in the sea, for protection & anchorage for muscles on land also for protecting against dessication also provides structural support for the body on land (buoyancy lost when they left the sea) Arthropod Characteristics
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This note was uploaded on 02/08/2012 for the course BIOL 119 taught by Professor Hannam during the Spring '11 term at SUNY Geneseo.

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Jan 25 - Biol 119 - 1/26/2012 Announcements Quiz will open...

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