Download Phylum Arthropoda (The Arthropods)

•By
far and away, the most
successful animal group
ever to live
•Consists of over 1 million
named species, 2 of every 3
animals are arthropods.
–Inhabit all ecosystems
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All have a hard exoskeleton
Composed of protein and chitin
 Allows for great variation in function biological "swiss army knives"
 Must molt as they grow
 Limits their size
Have well developed body segments and
appendages
Have well developed sensory organs
including true eyes and antennae
Have open circulatory systems & special gas
exchange organs
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Divided into 3 classes; Arachnida,
Merostomata & Pycnogonida
Body divided into 2 regions
 Abdomen
 Cephalothorax (fused head &
thorax)
Lack jaws
Have 6 appendages & no antennae
 First appendages form chilicerae
(frequently fangs)
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Very diverse class
Most species parasitic
or predatory
Many possess book
lungs for gas exchange
Spiders are able to
produce a strong
polymer - silk
Chilicera in form of
fangs
Tarantula
Black Widow
The brown recluse and its bite wounds
Dust Mite
Common Mite
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Ancient group of
species
Changed little over
350 million years
Aquatic, mostly
found on Atlantic &
gulf coasts of
United States
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Class Insecta (insects)
Class Chilopoda (Centipedes)
Class Diplopoda (Millipedes)
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Far & away the most diverse of animal groups
More types of insects alone than all other animal
groups combined
 Inhabit all terrestrial & freshwater ecosystems.
 Success largely attributed to coevolution with
flowering plants.
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Insects have 6 legs
3 body parts
 Head
 Thorax
 Abdomen
Most insects have wings, however in many species
these are vestigial
Have advanced excretory system composed of
malphygian tubules
Exchange gasses through a complex tracheal system
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Have complex compound eye which is usually
extremely sensitive to motion and allows 3600
vision
Most insects see well into the UV spectrum
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Insects usually have
specialized
jaws/mouthparts
suited to their
ecological niche
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Most insects undergo a process of metamorphosis - 2
types
Incomplete metamorphosis
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Larva similar to adult, with differing body proportions
Undergoes a series of molts resulting in adult phenotype
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Larva is very unlike adult phenotype
Envelopes self in a coccoon or chrysalis where
body breaks-down and reforms into adult form.
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Millipedes (diplopoda) are segmented worm-like animals
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Have 2 pairs of legs per segment
Primarily herbivores & decomposers
Centipedes (Chilopoda)
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Usually terrestrial carnivores
Have 1 pair of antennae
Are often poisonous, using modified front claws to immobilize prey
Centipede
Millipede
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Includes crabs,
lobsters,
crayfish, shrimp,
krill & barnacles
Over 40,000
species
Appendages are
often highly
specialized
Gas exchange is
usually through
gills
Many species
taste delicious in
butter
Crayfish
Marine Maine Lobster