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Explore the fascinating world of Phylum Nemertea & Phylum Chaetognatha. Discover their unique characteristics, habitats, feeding habits, and reproductive strategies. From delicate ribbon worms to swift arrow worms, delve into the mysteries of these marine creatures.
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Phylum Nemertea & Phylum Chaetognatha Ribbon Worms Arrow Worms Phylum Nemertea & Chaetognatha
Phylum Nemertea • Long, slender, soft unsegmented worms with an eversible proboscis Phylum Nemertea & Chaetognatha
The Proboscis Phylum Nemertea & Chaetognatha
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
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
Local Representatives • Milky ribbon worm (Cerebratulus lacteus) Phylum Nemertea & Chaetognatha
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
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
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
Reproduction Phylum Nemertea & Chaetognatha