THE ORIGIN AND PRIMITIVITY OF SUBMARINE CAVE ORGANISMS

1. 在一些潜水者的帮助下，研究了新成岛和大东岛的海底洞穴生物。根据这些岛屿的海底洞穴样本，以及在大阪、帕劳和菲律宾群岛收集的样本，我讨论了海底洞穴生物的原始性和起源，特别提到了软体动物。除了独特的特殊组成外，西北太平洋海底洞穴双壳类的共同显著特征是：(i)成年壳尺寸较小（小于5毫米），（ii）透明或半透明无色壳，（iii）许多脚底和半脚底物种，（iv）许多深水属，(v)频繁的由前遗传引起的幼体发育，（vi）低繁殖力和孵育优势。海底洞穴腹足类也包括许多最著名的深水属。从发育早期来看，海底洞穴古胃足类动物表现为直接发育或短期游动幼虫，而中、新胃足类动物表现为浮游营养性和远洋幼虫，与双壳类动物不同。虽然海底洞穴双壳类动物似乎主要局限于浅水、隐蔽的环境中，但海底洞穴腹足类动物通常来自邻近的深水底部，这表明这两类动物的起源不同。海底洞穴中双壳类和腹足类动物的壳结构和生活方式以古生代和中生代浅水底为主，在生态学上显示为原始，而在分类学上显示为原始。海底洞穴中不常见的捕食似乎是建立这种独特生物群的因素之一，这种情况类似于“中生代海洋革命”之前的浅水海洋底部。

1. Submarine cave organisms from Naisei and Daito Islands were investigated with the help of some SCUBA diviers. Base on the samples from the submarine caves of these islands as well as those collected from the Oagasasawa, Palau and Philippines Islands, I discussed the primitiveness and origin of the submarine cave organismas with special reference to the molluscs.2. In addition to the unique specific composition, common significant characteristics of the submarine cave bivalves in northwest Pacific are (i) reduced adult shell size (less than 5 mm), (ii) transparent or semi-transparent coloreless shells、(iii) many epifaunal and semi-infaunal species, (iv) many deepwater genera, (v) frequent paedomorphosis by progenetis, and (vi) low fecundity and dominance of brooding.3. Submarine cave gastropods also includes many genera most known from deepwaters. In view of early developnent, submarine cave archaeogastropods shows direct development or short-term swimming larvae, but the meso-and neogastropods are planktotrophic and pelagic larvae, the situation different from the bivalves.4. While the submarine-cave bivalve species seem to be limited mostly to shallow-water, cryptic environments, the submarine-cave gastropods are commonly known from the neighboring deepwater bottoms, suggesting different origins between the two groups.5. The bivalves and gastropods in the submarine caves show shell architectures and life styles that were dominated in Paleozoic and Mesozoic shallow-water bottoms, indicating primitivenes ecologically rather than taxonomically. Infrequent predation in the submarine caves seems to be one of the factors for estaglishing this unique biota, the condition similar to shallow-water marine bottoms before 'Mesozoic Marine Revolution'.