Download Ch. 28.1

Introduction to Arthropods
CH. 28.1
 Most successful animals of all time (based on
evolutionary success)
 ~75% of a million species are identified as
arthropods
What is an Arthropod?
 Segmented body
 Tough exoskeleton
 Jointed appendages
 EXOSKELETON: acts as protection and support
 Made of CHITIN protein and carbohydrate
 Exoskeletons have different sizes, shapes, and
toughness
 Some have adaptations to help stop water loss
 Jointed appendages: legs and antennae that extend
from the body wall.
Evolution of Arthropods
 Appeared more than 600 mya
 Live in aquatic, land, and air environments
 As time went on, the segments got smaller and more
specialized appendages appeared
Form and Function
 FEEDING: herbivores, carnivores, and omnivores
 Bloodsuckers, filter feeders, parasites, and detrivores
 Variety of mouthparts (fangs, pincers, etc.)
 RESPIRATION: most land dwelling arthropods have
TRACHAEL TUBES air enters and leaves through
small openings called SPIRACLES
 Some have BOOK LUNGS organs that have layers
of respiratory tissue
 Aquatic arthropods use gills
 CIRCULATION: open circulatory systems
 Well developed heart pumps blood through arteries
 EXCRETION: MALPIGHIAN TUBULES saclike
organs that extract wastes from blood and then add
to digestive wastes via the gut
 RESPONSE: well developed nervous system
 Brain and nerves (ventral nerve cord, ganglia, eyes,
and taste receptors)
 MOVEMENT: muscles actually contract and flex
 REPRODUCTION: terrestrial arthropods have
internal fertilization (egg and sperm)
 Aquatic arthropods may be internal or external
fertilization (females will release eggs and males will
shed sperm around the eggs)
 GROWTH AND DEVELOPMENT: Molting of
exoskeleton to fit growing body