| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1999: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1998: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1997: ¥1,100,000 (Direct Cost: ¥1,100,000)
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| Research Abstract |
The main purpose of this study is to clear the relationships between the morphological groups of predation scars on the valves of the shallow-water ostracodes from the Ryukyu Islands, including both living and fossil, and the ecology of the ostracodes.
The predation scars, which are the holes penetrating through ostracode valves, are grouped into the parabolic, cylindrical and irregular-shaped holes based on their morphology. The ostracodes bearing predation scars concist of the sandy bottom inhabitants, muddy bottom inhabitants and dwellers living on sea plants. The phytal species prevail in the recent reef ostracodes bearing predation scars. The carnivorous naticids and other gastropods have been considered to produce the drillholes such as the parabolic, cylindrical holes and part of the irregular-shaped holes. But, the carnivorous gastropods live only on sandy or muddy bottoms, and therefore, the predators attacking the phytal ostracodes remain to be inquired. The irregular-shaped holes frequently accompany the scars by scratching, scraping and solution on the outer valve surfaces around the holes. These evidences might suggest that the irregular-shaped holes include not only drillholes, but also the predation scars by cutting or piercing. Solution holes are also found in some ostracode valves. The solution holes can be due to digestive-solution or inorgamic solution.
The author reared some ostracodes of a particular species with its expected selective predators in the same container in a water tank, and tried to identify the predator to produce the predation scars, but failed. It is notable for the future trials that the water in the container should be kept in a good condition, and the 'candidates' of predators should be selected in consideration of the structures of appendages relevant to predation.
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