CHAPTER 10
SECTION 2
Arthropods
Characteristics of Arthropods
• Four major groups
• Crustaceans
• Arachnids
• Centipedes and Millipedes
• Insects
• Shared characteristics
• Invertebrates
• External skeleton
• Segmented body
• Jointed attachments called appendages (wings,
mouthparts, legs)
Outer Skeleton
• Exoskeleton
• Waxy covering, or outer skeleton
• Protects and helps prevent evaporation of water
(adaptation)
• When an arthropod grows…
• Molting occurs
• Molting: process of shedding an outgrown
exoskeleton
• New exoskeleton is soft for a little while, less
protection
Segmented Body
• Bodies made up of many identical-looking
segments
• Easily seen on millipedes and centipedes
• Normally three sections
• Head, midsection, and a hind section
Jointed Appendages
• Your fingers!
• Give the animal flexibility and enable it to
move
• Use legs to move, catch prey, defending against
predators
• Use antenna, has sense organs for smelling,
tasting, and touching
Crustaceans
• Shrimp, crabs, crayfish, lobsters
• Thrive in freshwater lakes and rivers
• Two or three body sections
• Five or more pairs of legs
• Two pairs of antennae
• Get oxygen from gills
• Life Cycle
• Crustaceans begin their lives as microscopic,
swimming larva and develop into adults by
metamorphosis (a process by which an animal’s body
undergoes dramatic changes in form during life cycle)
Arachnids
• Spiders, Mites, Scorpions, Ticks
• Two body sections (first body
section=head and midsection, hind
section=abdomen)
• Four pairs of legs
• No antennae
Arachnids
SPIDERS
MITES
• All spiders • Another
are
name is a
predators,
chigger
eat insects • Parasites
• Hollow
fangs,
inject
venom into
prey
• Rarely bite
people
SCORPIONS
• Live in hot
climates
• Active at
night
• Stinger at
end of
abdomen
TICKS
• Parasites
• Live on the
outside of a
hosts body
Centipedes and Millipedes
• Have two body sections and many pairs of legs
• Centipedes
• One pairs of legs attached to each segment
• Sometimes more than 100 segments
• Predators that inject venom into prey
• Millipede
• Two pairs of legs attached to each segment
• Sometimes more than 80 segments
• Scavengers