Data from: A highly social, land-dwelling fish defends territories in a constantly fluctuating environment

The Pacific leaping blenny (Alticus arnoldorum) is a marine fish that has made a highly successful transition to land. We report an extensive field study on the behavior of this remarkable fish and how it has coped with life on land. The fish occurs in great abundance above the waterline along the rocky coastlines of Micronesia. We found them to be terrestrial in all aspects of their adult daily life, but heavily constrained by large fluctuations in both tide and temperature with almost all activity limited to a brief period at mid-tide. Despite this, the fish were highly social and data were consistent with males defending exclusive territories on land. A variety of metrics – the use of visual displays, the allometry of ornaments, and sexual dimorphism – further imply sexual selection on both sexes was strong. Despite being restricted to an extremely narrow habitable zone in which conditions change constantly, the Pacific leaping blenny is remarkably adapted to life on land and rarely returned to water. The genus is unique among the living fishes in its degree of terrestriality and serves as a useful model of the constraints and adaptations that accompany major ecological transitions.太平洋跳鳚（Alticus arnoldorum）是一类成功实现向陆地生活过渡的海洋鱼类。本研究针对这一特殊鱼类的行为特征及其陆生生存适应机制，开展了系统性野外调查。该物种在密克罗尼西亚的岩质海岸潮上带区域种群数量极为丰富。研究发现，其成体的日常活动完全陆生，但受潮汐与温度的剧烈波动限制显著，几乎所有活动均集中在平潮期的短暂窗口内。尽管如此，该鱼类仍展现出高度的社会性，观测数据支持雄性会在陆地上划定专属领地。多项观测指标——包括视觉展示行为、装饰性结构的异速生长模式以及性二态性特征——均表明，该物种雌雄两性均受到强烈的性选择作用。尽管其适宜栖息范围极为狭窄且环境条件持续变化，太平洋跳鳚仍展现出极强的陆生适应性，极少返回水中。该属鱼类在现生鱼类中拥有独一无二的陆生适应程度，可作为研究重大生态转型过程中面临的约束与适应机制的理想模型系统。