Data from: Multimodal signals: ultraviolet reflectance and chemical cues in stomatopod agonistic encounters

Complex signals are commonly used during intraspecific contests over resources to assess an opponent's fighting ability and/or aggressive state. Stomatopod crustaceans may use complex signals when competing aggressively for refuges. Before physical attacks, stomatopods assess their opponents using chemical cues and perform threat displays showing a coloured patch, the meral spot. In some species, this spot reflects UV. However, despite their complex visual system with up to 20 photoreceptor classes, we do not know if stomatopods use chromatic or achromatic signals in contests. In a field study, we found that Neogonodactylus oerstedii meral spot luminance varies with sex, habitat and, more weakly, body length. Next, we conducted an experimental manipulation which demonstrated that both chemical cues and chromatic signals are used during contests. In the absence of chemical cues, stomatopods approached an occupied refuge more quickly and performed offensive behaviours at a lower rate. When UV reflectance was absent, stomatopods performed offensive behaviours more frequently and contest duration trended towards shorter fights. These results provide new evidence that UV reflectance and/or visible spectrum luminance is used to amplify threat displays. Our results are the first to demonstrate that chemical and chromatic cues comprise a multimodal signal in stomatopod contests.在争夺资源的种内竞争中，复杂信号通常被用于评估对手的格斗能力与/或攻击状态。口足类甲壳动物（Stomatopod crustaceans）在为庇护所发起攻击性竞争时，也可能使用这类复杂信号。在发起物理攻击前，口足类会借助化学线索评估对手，并开展威慑展示，露出带有色彩的斑块——颚足斑（meral spot）。部分物种的该斑块可反射紫外线（UV）。然而，尽管口足类拥有多达20种感光受体类型的复杂视觉系统，我们仍不清楚它们在竞争中是否会使用色觉信号或无色彩信号。在一项野外研究中，我们发现奥氏新螳螂虾（Neogonodactylus oerstedii）的颚足斑亮度会随性别、栖息环境变化，同时也与体长存在较弱的相关性。随后我们开展了实验操控，结果证实口足类在竞争中会同时利用化学线索与色觉信号。当缺乏化学线索时，口足类会更快接近已被占据的庇护所，且发起攻击行为的频率更低。当缺失紫外线反射时，口足类发起攻击行为的频率更高，且竞争时长呈现缩短的趋势。本研究结果为‘紫外线反射和/或可见光波段亮度可用于强化威慑展示’提供了新的佐证。本研究首次证实，在口足类的竞争行为中，化学线索与色觉信号共同构成了多模态信号。