Ocean is generally a major barrier of migration for most flightless land animals; however, terrestrial flightless insects often demonstrate wide range distribution across oceans. To elucidate the mechanism of flightless insects to expand their distribution over the sea, we measured the survivorship of nine species of coastal beetles on seawater (i.e. seawater tolerance). We observed that two out of nine coastal beetle species showed over 10 days of median survival days (50% death days), and nearly 1 month of maximum survival days. From the unexpectedly long survival on the surface of seawater, we propose the hypothesis of “floating dispersal,” where individuals simply float on the sea surface and cross the ocean with currents. This mode can provide a novel explanation of transoceanic migration/distribution of flightless animals.

中文翻译：

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多种沿海甲虫在海水中出人意料的长期存活表明跨洋迁徙“漂浮分散”的可能性

海洋通常是大多数不会飞的陆地动物迁徙的主要障碍。然而，陆生不会飞的昆虫通常表现出跨越海洋的广泛分布。为了阐明不会飞的昆虫扩大其在海上分布的机制，我们测量了九种沿海甲虫在海水中的存活率（即海水耐受性）。我们观察到，九分之二的沿海甲虫物种显示出超过 10 天的中位生存天数（50% 的死亡天数）和近 1 个月的最大生存天数。从出乎意料地在海水表面长期存活，我们提出了“漂浮扩散”假说，即个体简单地漂浮在海面上，随洋流穿越海洋。这种模式可以为不会飞的动物的越洋迁徙/分布提供一种新的解释。