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Phylum Nemertea & Phylum Chaetognatha

Phylum Nemertea & Phylum Chaetognatha. Ribbon Worms Arrow Worms. Phylum Nemertea. Long, slender, soft unsegmented worms with an eversible proboscis. The Proboscis. Digestion and Circulatory Systems. Lacks an exoskeleton; skin is densely ciliated which circulates water for gas exchange

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Phylum Nemertea & Phylum Chaetognatha

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  1. Phylum Nemertea & Phylum Chaetognatha Ribbon Worms Arrow Worms Phylum Nemertea & Chaetognatha

  2. Phylum Nemertea • Long, slender, soft unsegmented worms with an eversible proboscis Phylum Nemertea & Chaetognatha

  3. The Proboscis Phylum Nemertea & Chaetognatha

  4. Digestion and Circulatory Systems • Lacks an exoskeleton; skin is densely ciliated which circulates water for gas exchange • Eyespots are located on the head near the brain • Food is digested rapidly and processed in a linear digestive tract Phylum Nemertea & Chaetognatha

  5. Reproduction • Sexes are separate with fertilization occurring in the water column • Usually solitary animals that aggregate at spawning • Long lived free-swimming larvae pilidium • Great powers of regeneration Phylum Nemertea & Chaetognatha

  6. Local Representatives • Milky ribbon worm (Cerebratulus lacteus) Phylum Nemertea & Chaetognatha

  7. Phylum Chaetognatha (Arrow Worms) • Defining Characteristics • A series of curved chitinous grasping spines on both sides of the head, for seizing prey • Lateral stabilizing fins Phylum Nemertea & Chaetognatha

  8. Chaetognaths Habits • Living Chaetognaths are almost invisible in the water • Possess two eyes that are useful for sensing motion and light intensity Phylum Nemertea & Chaetognatha

  9. Chaetognatha Feeding • A prey item is sensed by cilia along the body • Feed on copepods, larval crustaceans, young fish and each other • Can occur in very high concentrations several hundred per cubic meter • Can have substantial effects on eggs and larvae some of which are commercially important Phylum Nemertea & Chaetognatha

  10. Reproduction Phylum Nemertea & Chaetognatha

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