Arthropods

By Devin Holmes

Arachnida

SPIDERS• 2 body regions• 6 pairs of jointed appendages• First 2 pairs used for feeding• Other appendages are modified as legs for

locomotion• Have no antennae• All spin silk; all do not make webs

Arachnida

TICKS• One body section• Feed on blood• Can expand to 1cm• Can carry disease

ArachnidaMITES• One body section• Usually no visible to the naked

SCOPIONS• Enlarged pinchers, tail with venomous stinger• Live in warm, dry climate• Eats insects and spiders• Paralyze large prey with poison

Crustacea

• Most are aquatic and have feathery gills• Only arthropods that have two pairs of

appendages• Have mandibles for crushing food• Two compound eyes• Many have five pairs of walking legs• Have two or three body parts• Examples: crabs, lobster, water fleas, shrimp,

crayfish, barnacles

Chilopda

Centipedes• Carnivorous-eat soil arthropods, snails,

slugs, and worms• Bite is harmful to humans• Have tracheal tubes for gas exchange• 15 to 181 body parts (always an odd

number)

Diplopoda

Millipedes• Eats mostly plants and dead material• Do not bite• Can spray obnoxious-smelling fluid• 100 segments-each with 2 spiracles and 2

pairs of legs

Merostomata

Horseshoe crabs• Considered living fossils• Unchanged from over 500 million years

ago• Protected by exoskeleton• Migrate to shallow water during mating

season• Female lays eggs on land

Insecta

Insects• Most successful arthropods• Largest group• More species of insects than all other of classes

of animals combined• Mate once or just a few times• Internal fertilization• examples: flies, grasshoppers, butterflies, bees,

and beetles