Life history strategy of the chaetognath Sagitta elegans in the World Oceans

• Main Authors: Terazaki, Makoto, 139705
• Language: English
• Published: International Coastal Research Center, Ocean Research Institute, the University of Tokyo 2004
• Subjects: 452; distribution; migration; breeding; life cycle; feeding; Arctic; Bedford; Bering Sea; Pacific; Subarctic; Copepods
• Online Access: https://repository.dl.itc.u-tokyo.ac.jp/record/40827/files/KJ00004098935.pdf

application/pdf Sagitta elegans is the best-studied chaetognatha in the world ocean. This species typically inhabits the upper 100 to 150m in the arctic and subarctic area of both the Atlantic and Pacific. S. elegans was also reported from the North Pacific Intermediate Water and the meso- and bathypleagic layer in the Sea of Japan. Diurnal vertical migration is recognized in the various waters. The size and number of grasping spines and teeth of S. elegans in the Sea of Japan are greater than those from the Pacific. They also have developed intestinal tissue containing oil droplets similar to meso- and bathypelagic species. These features are adaptations to the deep-water environment. Number of generations per year, life span and growth rate depend on the waters inhabited. In general, S. elegans mature at large sizes in lower temperatures and life span is short in warm regions. Food is also an important factor controlling their growth. Feeding activity of S. elegans in the various waters of the Pacific is high during the night time. The major food organisms are copepods. S. elegans inhabiting the open sea consume larger copepods compared to those in coastal waters. The percentage of secondary production consumed daily by S. elegans, was 36% in Bedford Basin, Nova Scotia, 10% in the Bering Sea and 4% in the western North Pacific, respectively. departmental bulletin paper