Download Phylum Arthropoda

Coelomate Animals
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Have a true coelom, not a pseudocoelom
True coelom is a hollowed out space inside the
mesoderm, not a space between tissue layers
Coelom provides space for organs to develop
2 Groups of Animals have Coeloms
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Protostomes
mouth forms first
Phylum Mollusca
Phylum Annelida
Phylum Arthropoda
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Deuterostomes
anus forms first
Phylum Echinodermata
Phylum Chordata
New Traits of All Coelomates
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Circulatory systems that pump blood
Excretory systems = kidney
Respiratory structures present in most species
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Gills in: - some Mollusks
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Lungs in: - some Mollusks
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Some Arthropods (Crustaceans)
Some Chordates (lamprey, Fish, larval Amphibians)
Lung fish
Some Chordates (adult Amphibians, Reptiles, Birds, Mammals)
Trachea in: Insects
Book lungs in: Arachnids
Phylum Molluska
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Shell excreted by mantle
Muscular foot
Gills or lung (snails)
Class Bivalvia
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Name means 2 shells
Most are filter feeders
Clams, oysters, mussels,
scalops
Class Gastropoda
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Name means Stomach-Foot
snails, slugs & nudibranchs (sea slugs)
some have lungs
Class Cephalopoda
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Name means head-foot
Squids, octopuses, nautiluses, cuttlefish
Highly developed brain, human like eye (c. evol)
Largest inverts : huge nerve axon = low resistance
Cephalopod Derived Traits :
Adaptations of a Predator
Shell filled with chambers of air for buoyancy
 Shells lost or small & internal = less weight
 Closed circulatory system = faster circulation
for better delivery of oxygen to muscles
 Well developed eyes and brain = must be
smarter than the food
 Foot converted to tentacles
and siphon (jet propulsion)
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Phylum Annelida:Segmented worms
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Earth worms
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Marine Worms
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Leeches
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Freshwater
worms
Annelid traits
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Body divided into segments
Advantages of segmentation…
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Repeating body parts allows evolution of one
segment while another segment maintains
original function
Phylum Arthropoda
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Subphylum Crustacea
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Class Arachnida
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Class Insecta
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Classes
Diplopoda/chilopoda
Arthropod Traits
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Name means jointed-foot
Also have jointed legs
Segmented bodies
Exoskeleton (chiton)
Open circulatory system
Insect Innovations
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Respiration using tracheae –tubes that branch
throughout the body
Compound eye
Wings
Complex life cycle
Arachnids
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Respiration by book lungs
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spiders
ticks
mites
Scorpions
harvestmen
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May have silk glands to make web
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Crustacea
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Nearly all aquatic
Respiration by gills
Important part of zooplankton