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PHYLUM: ARTHROPODA
• arthro – Greek for JOINTED
• poda – Greek for FOOT
• JOINTED FEET!!!
THE KEY FEATURE OF ARTHROPODS
• An exoskeleton
EXOSKELETON
• Does not grow so the arthropods must molt• http://www.youtube.com/watch?v=n6iQ96emYE0• http://www.youtube.com/watch?
v=ngebZ6n1vVY
MOLTING
NOTICE THE HOLE?
OTHER FEATURES:
• Malpighian tubules – excretion• Many have complex nervous systems• Better eyes• Sensory abilities• Social abilities• Antennae
• Open circulatory system• Hemocoel is the major body cavity
MORE FEATURES
• Tracheal system – respiratory system connected to the atmosphere• Fertilization is mostly internal• Some eggs hatch into adult looking form• Some have a larval stage which doesn’t resemble
the adult • Metamorphosis!!
FOUR SUBPHYLA
• Trilobitmorpha• Trilobites
• Chelicerata• Arachnida (spiders, scorpions, ticks, mites)
• Crustacea• Lobsters, crabs, and crayfish
• Uniramia• Myriapods and insects
TRILOBITES ARE EXTINCT
CHELICERATES HAVE NO ANTENNAE
CHELICERATES HAVE NO ANTENNAE
CHELICERATES HAVE NO ANTENNAE
CRUSTACEA
• 2 pairs of antennae3 pairs of appendages around the mouth
• Modified body appendages for walking and swimming
• Branched appendage
CRUSTACEA
CRUSTACEA
UNIRAMIA
• Uniramous• Jointed but UNBRANCHED appendages
UNIRAMIA - MYRIAPODS
• Millipedes and centipedes
UNIRAMIA: INSECTS!!!!
• All have 3 pairs of legs (6 feet) on the thorax• All have a single pair of antennae• All have a pair of compound eyes
ECOLOGICAL ROLES
+ pollinate many of the world’s plants (integral part of agriculture)“If the bee disappeared off the surface of the globe
man would only survive for four years” –Albert Einstein
+ arthropod predators kill pest organisms by the millions
+ direct/indirect food source for countless organisms
+ lobsters, crab, crayfish and shrimp are an important food source for humans