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