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Eukrohnia hamata Heterokrohnia Sagitta elegans
Eukrohnia hamata Heterokrohnia Sagitta elegans
Sagitta maxima Heterokrohnia involucrum head  
Sagitta maxima Chaetognath head  

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Chaetognaths (arrow worms)

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Chaetognaths or arrow worms are lay-and-wait ambush predators on other zooplankton. When they feel their prey are close, they dart out grabbing then with strong hooks stored at the side of their head. Prey are then ratched whole down into the mouth with smaller teeth. We can see exactly what they have eaten through thier transparent bodies.

Gulf of Alaska chaetognaths can be as large as 6-8 cm. They can be found all the way from the surface to the bottom of the ocean, with some species specialized to live just above the seafloor. We know little for sure about how long most species live in the Gulf of Alaska, but it is likely 4-12 months. Some deepwater species carry their eggs in a marsupium until they hatch.

Page Author: Russ Hopcroft
Created: January 01, 2009