Distinguishing characteristics of phylum Annelida

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• Distinguishing characteristics of phylum Annelida
• Segmented worms
• Setae
• Large compartmentalized coelom hydrostatic
  skeleton

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Annelids

• Closed circulatory system
• Dorsal vessel carries blood away from heart
• Ventral vessel back to heart
• Blood pigments
• many have hemoglobin
• Some Polychaetes have Chlorocruorin (Fe)
• And Hemerythrin (Fe)

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• Phylum Annelida
• Class Polychaeta marine sand worms
• Class Clitellata
• Oligochaeta earthworms
• Hirudinea leeches

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Figure 13_01
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Figure 13_02
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• Polychaeta
• Marine worms with
• Parapodia for locomotion and gas exchange
• Setae on parapodia
• Separate sexes mostly, external fertilization
  mostly
• Trochophore larva
• Develops by growing new segments

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Figure 13_07
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Figure 13_11
Polychaete trochophore
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• Oligochaeta
• Earthworms 3500 species
• A few short setae per segment
• Body divided into more than 100 segments
  separated internally by septa

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Figure 13_27
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Figure 13_36
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Oligochaete reproduction

• Hermaphroditic
• Individuals exchange sperm
• Eggs fertilized later in clitellum cocoon
• No larval stage

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Figure 13_35
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• Hirudinea
• Leeches 500 species
• Mostly freshwater
• No head appendages (prostomium)
• Most do not have setae
• Suckers for locomotion and holding onto host

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Hirudinea

• Many are ectoparasites medical use
• Hirudin anticoagulant
• 25 not parasites
• carnivores, detritivores

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Hirudinea reproduction

• Simultaneous hermaphrodites
• Clitellum functions as cocoon
• No larval form