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


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.

Arctic 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 Arctic, but it is likely ~1 year. Some deepwater species carry their eggs in a marsupium until they hatch.

Only five (5) species of chaetognaths are recorded as present in the arctic, although additional species may occur in the Arctic's marginal regions.

Page Author: Russ Hopcroft
Created: January 26, 2008

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