2000 Fiscal Year Final Research Report Summary
Sparial/temporal feeding strategies of pelagic copepod commonities
| Project/Area Number |
10660180
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
General fisheries
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| Research Institution | Hiroshima University |
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Principal Investigator |
OHTSUKA Susumu Hiroshima University, Faculty of Applied Biological Science, Associate Professor, 生物生産学部, 助教授 (00176934)
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| Co-Investigator(Kenkyū-buntansha) |
NISHIDA Shuhei University of Tokyo, Ocean Research Institution, Associate Professor, 海洋研究所, 助教授 (70134658)
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| Project Period (FY) |
1998 – 2000
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| Keywords | copepod / detritus / carnivore / phytoplankton / Tortanus / Macandrewella / Cephalophanes / harpacticoid |
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| Research Abstract |
1. A neritic calanoid copepod Tortanus (Atortus), which is a carnivore feeding on small copepods such as Oithona, was observed forming swarms during the day. Their swarming may function, not only as an antipredation against visual predators such as fish, but also a foraging strategy to detect prey copepods.
2. A deep-sea hyperbenthic calanoid copepod Macandrewella is a special detritivore utilizing crustacean carsasses and/or molts. The genus bears a medial cephalic lens which is rarely found in the family Scolecitrichidae, Another deep-sea calanoid Cephalophanes with much more developed and specialized optical sensors than in Macandrewella is also a detritivore feeding mainly on crustacean carcasses/molts. Considering their similar feeding habits and developed optical sensors, these organs may function in detecting bioluminescent bacteria inhabiting on crustacean detrital matter.
3. Shallow-water demersal calanoid copepods such as Pseudodiaptomus and Pseudocyclops utilize benthic algae
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in addition to pelagic ones. A cavernicolous calanoid Ridgewayia stygia fed on crustacean remains.
4. A deep-sea carnivorous catanoid Euaugaptilus bears special setae called "button setae" on the maxilla and maxilliped. The "button" may function as a shock absorber white their prey is struggling. The number, disposition and fine structure of the buttons vary among congeners.
5. Pelagic harpacticoid such as Euterpina acutifrons, Microsetella norvegica and Aegisthus murconatus fed mainly on small algae ranging from 4 to 15 μm in largest dimension. In addition, A.mucronatus frequently fed on crustacean remains.
6. Ratios of the maxillary and maxillipedal lengths to the body length are measured in 85 species of oceanic, neritic and brackish calanoid copepods. Only oceanic carnivores bear extremely elongate maxillae (>30% in Candaciidae) or maxillipeds (>40% in Euchaetidae and Chiridiella). The appendage elongation seems to guarantee effective capture of prey zooplankters in oligotrophic waters. However setal ornamentations on these mouthpart appendages greatly vary among these carnivores, suggesting that they employ different feeding modes to result in food segregation. Ratios of the maxilla and maxilliped in particle feeders fall within 5-15% and 10-40%, respectively. Less
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