Phylum Arthropoda
Arthropoda Overview
Subphylum Chelicerata
Class Merostomata
Class Pycnogonida
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Phylum Arthropoda
Phylum Arthropoda
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Defining Characteristics
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Epidermis produces a segmented, jointed and
hardened chitinous exoskeleton with musculature
between individual joints of appendages
Complete loss of motile cilia in adult larval stages
Phylum Arthropoda
Phylum Arthropoda
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Phylum includes crustaceans, insects, and
chelicerates
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Chelicerates
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Crustaceans
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Primarily terrestrial
Also horseshoe crabs and sea spiders
Marine and freshwater, absent from land
Phylum Arthropoda
Arthropod Characters
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Arthropods have segmented
bodies with some or all of the
segments bearing jointed
appendages
Appendages are specialized
for:
Phylum Arthropoda
The Wonders of Chitin
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All arthropods have a
chitinous jointed
exoskeleton
How is this detrimental
and beneficial?
Phylum Arthropoda
Molting (Ecdysis)
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Phylum Arthropoda
Arthropod Segments
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Arthropod segments are grouped into body
regions
Some have two regions
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Some have three regions
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Head, thorax, abdomen
Many regions have multiple appendages
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Cephalothorax, and abdomen
Appendages are modified for a particular function
Phylum Arthropoda
Arthropod Appendages
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The head usually contains pairs of joint
appendages, which are sensory and used in
feeding
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Antenna’s or feelers are first
Followed by the jaws and mandibles which are
used for biting and chewing
 Mandible
and accessory mouth parts aid in
handling the food and moving it towards the
mouth
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Phylum Arthropoda
Arthropod Appendages
Arthropod Vision
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Simple eyes
– Light sensitive cells
share a common lens
Compound eyes
– Thousand of closely
packed units called
ommatidia
Phylum Arthropoda
Compound & Simple Eyes
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Phylum Arthropoda
Digestive system
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Most arthropods have three main regions:
foregut, midgut and hindgut
Phylum Arthropoda
Respiration and Circulatory System
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Extensive surface areas are needed to supply the
large oxygen demands of most arthropods
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Circulatory System
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Gills can occur both inside and outside of the of the
carapace
Open circulatory system as in molluscs, hearts vary in
structure but do exist
Blood is pumped into empty spaces bathing the tissues
in blood
Phylum Arthropoda
Nervous System and Reproduction
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Phylum Arthropoda