Palaebiological study of 'living fossils' (1991)

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1. Abe and Tsukagoshi visited Australia in July to attend and preset papers at the 11th International Symposium on Ostracods. And they discussed on a living ostracod, Manawa with Dr. Swanson who have discovered living specimens of Manawa from off Newzealand. Abe investigated functional morphology of the carapace and appendages of myodoeopid ostracods through the time from Palaeozoic to Recent. Tsukagoshi noticed the segmentation in the soft parts of some podoeopid ostracods, and studied the evolution of ostracods in general.2. Hayami and Kase found a rich molluscan assemblage in several submarine caves in Ryukyu, and its morphological and ecological uniqueness was examined. This fauna contains 'living fossil' genera, Neritopsis and Pycnodonte, and numerous minute molluscs which are surprisingly similar to deep-sea fauna in generic assemblage and developmental strategy.3. Oji collected living crinoids from Suruga Bay and cultured them, obtaining much information about their ecology, functional morphology and regeneration of arms after the autotomy.4. Yoshida examined plate tectonics in the South Pacific region, providing a basic knowledge to investigate the process how the present-day distribution patterns of the living fossils were made through a geologic time.5. Abe studied mating behaviour of ostracods using VTR, and found that the morphological features of appendages are better described in the context of premating or courtship behaviour of the species. Similar approach will be applied to Manawa to understand the evolution of mating behaviour of ostracods.--- Various important and useful knowledge has been obtained about 'living fossils' in the South Pacific region. Molecular biological aspects will be examined hereafter, to clarify the process how and why these living fossils have kept their morphology unchanged through a long geological time.