Echiura By Freeda Battle BIO 235 May 12, 2003

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EchiuraBy Freeda BattleBIO 235May 12, 2003
http//www.ucmp.berkeley.edu/annelida/echiura.html
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Taxonomic Debate

• With Annelids
• Segmentation

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• Echiurans have segmentation during their larval
  stage

Shanks, Alan L. An Identification Guide to the
Larval Marine Invertebrates of the Northwest,
Oregon State University Press 2001 (p85)
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• Adult stage shows no segmentation

http//www.earthlife.net/inverts/images/others/ech
iura.jpg
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Size

• Varies from few millimeters to 50cm
• Proboscis can extend 25x length of trunk

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Anatomy
www.ldeo.columbia.edu.dees/ees/life/slides/phyla/e
chiura.html
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Habitat

• Under substrates
• Some at shores
• Some deep below ocean floor

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Diet

• Most are detritus feeders
• The innkeeper worm is a suspension feeder

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Detritus feedingEchiurus echiurus
Pechenik, Jan A Biology of the Invertebrates 4th
ed. Mcgraw Hill Co. 2000 (p300-304)
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Suspension FeedingUrechis caupo
Pechenik, Jan A Biology of the Invertebrates 4th
ed. Mcgraw Hill Co. 2000 (p300-304)
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Reproduciton

• All echiurans are dioecious
• Fertilization is external
• Lack distinct gonads
• Gametes are produced by peritoneal lining of the
  coelom and are released into the coelomic cavity
• Sexual dimorphism in Bonellia viridis

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Bonellia viridis
Pechenik, Jan A Biology of the Invertebrates 4th
ed. Mcgraw Hill Co. 2000 (p300-304)
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Pechenik, Jan A Biology of the Invertebrates 4th
ed. Mcgraw Hill Co. 2000 (p300-304)