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

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

3. Phylum Nemertea & Chaetognatha
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. 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

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

9. 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

10. 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

11. Phylum Nemertea & Chaetognatha
Reproduction
Phylum Nemertea & Chaetognatha