Arthropoda

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• Arthropoda
• Crustacea
• Decapoda (order)
• Crabs, true shrimp, lobsters
• Most species in Crustacea (10,000)
• Scavengers/Predators/Both
• Five pairs of walking legs
• First pair usually modified as claws for
  feeding/defense
• Well-developed carapace cephalothorax
• Rest of body abdomen
• Lobsters, shrimp Usually laterally compressed
• Tail/Abdomen behind thorax
• Crabs Usually dorsoventrally compressed
• Tail/Abdomen curled underneath thorax
• Largest crustaceans
• Lobster gt 42 lbs
• Crab gt 13 feet tall

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Hermit crab
Decorator crab
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• Arthropoda
• Crustacea
• Decapoda (order)
• Crabs, true shrimp, lobsters
• Most species in Crustacea (10,000)
• Scavengers/Predators/Both
• Five pairs of walking legs
• First pair usually modified as claws for
  feeding/defense
• Well-developed carapace cephalothorax
• Rest of body abdomen
• Lobsters, shrimp Usually laterally compressed
• Tail/Abdomen behind thorax
• Crabs Usually dorsoventrally compressed
• Tail/Abdomen curled underneath thorax
• Largest crustaceans
• Lobster gt 42 lbs
• Crab gt 13 feet tall

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Fig. 9-35
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• Arthropoda
• Crustacea
• Decapoda (order)
• Diverse nutritional modes predators (Ex
  lobsters), deposit feeders (Ex fiddler crabs),
  suspension feeders (Ex mole crabs)
• Dioecious
• May exhibit courtship behavior, territoriality
• Males often transfer spermatophores to female
  with modified copulatory pleopods
• Fertilization usually internal
• Eggs usually brooded
• Larvae pelagic
• Nauplius shrimp, other crustaceans
• Zoea crabs

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Nauplius
Zoea Fig. 9-36
Megalopa
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• Arthropoda
• Crustacea
• Copepoda
• Extremely abundant and important plankton
• Among most abundant animals on earth
• Benthic forms also important
• Important primary consumers of phytoplankton
• Many exhibit DVM
• Some parasitic forms

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Harpacticoid copepods
Parasitic copepods
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Herbivorous vs. Predatory Copepod
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• Arthropoda
• Crustacea
• Euphausiacea (krill)
• Laterally compressed
• Up to 10 cm long (usually smaller)
• Head and anterior segments fused to form distinct
  carapace
• Widespread distribution
• Important primary consumers and predators
• Important prey for larger consumers
• Keystone species in some ecosystems (Southern
  Ocean)
• Aggregate in schools
• May be immense (450 sq km x 200 m _at_ gt1000 m-3)
• May molt rapidly predator avoidance?

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• Arthropoda
• Crustacea
• Amphipoda
• Laterally compressed
• Generally small (lt 2 cm), but larger in deep
  ocean
• Widespread distribution
• Generally free living
• Important scavengers
• Often highly mobile
• Some sedentary forms
• Diverse lifestyles
• Brood young

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• Arthropoda
• Crustacea
• Isopoda
• Dorsoventrally compressed
• Generally small (lt 2 cm), but larger in deep
  ocean
• Related to terrestrial pill bugs
• Widespread distribution
• Generally free living
• Important scavengers
• Often highly mobile
• Some parasitic forms
• Brood young

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• Arthropoda
• Crustacea
• Cirripedia (barnacles)
• Active suspension feeders (filter feeders)
• Use feathery cirripeds (modified swimming
  appendages)
• Sessile (attached to surfaces)
• Fouling organisms (boats, hard surfaces, whales)
• Resemble mollusks superficially
• Some parasitic forms
• Simultaneous hermaphrodites
• Internal fertilization (How??)

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Stalked
Sessile
Fig. 9-41
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• Arthropoda
• Crustacea
• Cirripedia (barnacles)
• Active suspension feeders (filter feeders)
• Use feathery cirripeds (modified swimming
  appendages)
• Sessile (attached to surfaces)
• Fouling organisms (boats, hard surfaces, whales)
• Resemble mollusks superficially
• Some parasitic forms
• Simultaneous hermaphrodites
• Internal fertilization (How??)

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• Arthropoda
• Crustacea
• Stomatopoda (mantis shrimp)
• Specialized predators
• Modified second pair of thoracic appendages
• Smashers (eat mollusks, crabs) Video Video
• Spearers (eat shrimp, fishes)
• Sophisticated eyes
• Three lobes (midband for color vision)
• Up to 16 photoreceptor types (humans have four)
• Can see ultraviolet polarized light
• Reproduction
• Female lays egg mass
• Zoea larvae in plankton up to three months