ARTHROPODA
Gk. “arthros”– joint + “podos”– foot
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What Is Different about Each of These Animals?
Size
Shape
Color
Method of Movement
What Do These Animals Have In Common?
Jointed Legs
Segmented Body
Exoskeleton
Distinct Head
Compound Eyes
(most cases)
GENERAL CHARACTERISTICS
• Common throughout marine, freshwater,
terrestrial, and even aerial environments
Characteristics of Arthropods
Segmented
Jointed appendages
Hard external skeleton
3 parts-head, thorax, abdomen (arachnids
exception)
 Exoskeleton-hard, external skeleton made
of chitin
 Molting- shed old exoskeleton and secrete
a larger one, very vulnerable after molting
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• Complete digestive tract (mandible-chewing
or proboscis- sucking) with a dorsal heart and
a ventral nervous system
• Respiration through gills, trachea, book
lungs or body surface
• Sensory organs include antennae and hairs,
simple and compound eye
• Reproduces (mostly sexually), one to several
larval stage
• The muscle system is more or less assisted by
hydraulics originated from the blood pressure
created by the heart
• Respiration through gills, trachea, book
lungs or body surface
• With open circulatory system. Haemolymph
that contains haemocyanin, a copper-based
oxygen-carrying protein
Body parts
 Ganglia-clusters of nerve cells along a
nerve cord
 Compound eyes-may facets each with
their own lenses, some have single lenses
and some have both
 Spiracles-holes in the exoskeleton that
allow gas exchange (book lungs in
arachnids)
 Trachea-chitin lined tubes in spiracles
Four SUBPHYLA of Arthropods
 Trilobita – thought to be the oldest
arthropods
 Chelicerata – two part body and
mouthparts called chelicerae
 Crustacea – hard exoskeleton, two pairs
of antennae, mouthparts called
mandibles
 Uniramia – contains more species than
all other groups of animals alive today
REPRESENTATIVE ORGANISMS:
SUBPHYLUM - Trilobites
• CLASS TRILOBITA – Trilobites
SUBPHYLUM CHELICERATA
• CLASS ARACHNIDA – Spiders, Scorpions, Ticks
• CLASS MEROSTOMATA – Horseshoe crabs
• CLASS PYCNOGONIDA – Sea spiders
SUBPHYLUM UNIRAMIA
• CLASS CHILOPODA – Centipedes
• CLASS DIPLOPODA - Millipedes
• CLASS INSECTA – Insects
• Class Branchiopoda – Brine shrimp
• CLASS CEPHALOCARIDA – Horseshoe shrimp
• CLASS MAXILLOPODA – Barnacles, and
Fish lice
• CLASS MALACOSTRATA – Lobsters, Crabs,
and Shrimps
Blue crab
Callinectes
sapidus
American
lobster
Homanus
americanus
CLASS CRUSTACEA
Lobsters, Crabs and Shrimps
ORDER COLEOPTERA
Weevil
ORDER
HYMENOPTERA
Fire ant
Solenopsis
invicta
ORDER
ORTHOPTERA
Migrating locust
Locusta migratoria
Beetle
CLASS INSECTA
Ants, Beetles and Bugs
MAJOR PARTS OF AN INSECT
Insects that have piercing and sucking
mouthparts are called BUGS while BEETLES
are insects distinguished as those having
forewings modified into hard wing cases that
cover and protect the hind wings and
abdomen!
Wolf spider
Lycosa tarentula
CLASS ARACHNIDA
Spiders, Ticks and Scorpions
The Goliath
Bird-eating tarantula (Theraphosa
blondi) But can grow as much as 1 ft
in diameter!
CLASS MEROSTOMATA
Horseshoe crabs
Peruvian Giant
CLASS CHILOPODA
Centipedes
Harpaphe haydeniana
CLASS DIPLOPODA
Millipedes
CLASS TRILOBITA
Trilobites
LIFE CYCLES OF
SOME INSECTS
LIFE CYCLE OF A DRAGONFLY
(CLASS INSECTA ORDER ODONATA)
LIFE CYCLE OF A FRUIT FLY
(CLASS INSECTA ORDER DIPTERA)
(Larva)
Caterpillar
(Pupa)
Chrysalis
LIFE CYCLE OF A BUTTERFLY
(CLASS INSECTA ORDER LEPIDOPTERA)
LIFE CYCLE OF A GRASSHOPPER
(CLASS INSECTA ORDER ORTHOPTERA)
MIMICRY AND CAMOUFLAGE
Mimicry - take on the appearance of (another animal or
plant) in order to deter predators
Camouflage - the natural coloring or form of an animal
which enables it to blend in with its surroundings
ECOLOGICAL IMPORTANCE
• Serve as food source for both animals and
humans
• Aid in the propagation of plant species by
means of cross-pollination
• Control the population of some harmful
organisms
• Some act as scavengers or saprotrophs