Phylum Arthropoda

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Phylum Arthropoda

• Major arthropod features
• Body segementation/specialization of regions
• Paired, jointed appendages
• Exoskeleton

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Steps of molting

• Cuticle separates from epidermal layer
• Space fills with molting fluid
• New exoskeleton
• Enzymes digest most of old procuticle
• Old cuticle splits, animal crawls out
• Gut fills with water, stretching new exoskeleton

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Phylum ArthropodaSubphylum Crustacea features

• Two pair of antennae, followed by three pairs of
  mouthparts
• Compound eyes, sometimes on stalks
• Head and thorax combined into a cephalothorax
• Biramous (double-branched) appendages
• Often with calcium carbonate cuticle
• Many have gills

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Order Amphipoda(Beach hopper)
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Order Isopoda
Idotea sp.
Ligia pallasii
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Order Decapoda

• Carapace completely covers head and thorax
• Eight pairs of thoracic appendages
• 3 as modified mouthparts (maxillopeds)
• 5 pairs as walking legs

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Order Decapoda
Petrolisthes cinctipes
Pagurus sp.
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Shore crabs
Hemigrapsus nudus
Pachygrapsus crassipes
Hemigrapsus oregonensis
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Cancer sp. crabs
C. antennarius
C. productus
Not shown C. oregonensis
C. magister
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Pugettia producta kelp crab
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Order Cirripedia the barnacles
Balanus sp.
Pollicipes polymerus
Chthamalus sp.