EAGER: Natural Chromogenic Behaviors of Squid in Oceanic Waters

鱿鱼复杂的变色(发色)行为通过模仿岩石、珊瑚或藻类等底栖生物特征提供伪装，也起到种内信号的作用。然而，很少有研究在野外的自然光照条件下进行，或者在没有人类观察者或嘈杂的遥控车辆的情况下进行。该项目将把对自然发色行为的实地研究扩展到长吻乌贼科，如大乌贼(洪堡鱿鱼)。为了在自然光条件下完成这项研究，该项目将开发一种改进的微光Crittercam和一种改进的漂移cam，可以在更深的地方有效地工作。这些改进的视频平台将使人们对远洋环境下伪装和通信的产生和监管有新的认识。人们对洪堡鱿鱼在中水区域的捕食行为知之甚少，因为在东太平洋，洪堡鱿鱼与大量天然缺氧的水有关，称为氧气最小区域(OMZ)。这个OMZ目前正在扩大并向地表移动，这主要是由于气候变化。对OMZ上层捕食活动的观察将增加我们对远洋生态系统如何随着气候变化的进展而变化的理解，以及这些变化如何影响洪堡鱿鱼等重要的经济和生态物种。鱿鱼和其他头足类动物的发色行为是由称为着色器的肌肉器官产生的，这些器官受大脑中的神经活动控制，这种对着色器的直接下行运动控制是头足类动物独有的。利用国家地理遥感成像(NGRI)“Crittercam”视频包在自然光照下自由游泳的洪堡进行的初步研究揭示了静态图案型显示，就像在舌状目物种中看到的那样，以及一种独特的“闪烁”行为，整个身体在淡白色和深红色之间快速交替。闪光似乎只发生在与同种生物的互动中，这强烈地表明了一种交流作用。这些数据还揭示了一种更微妙的波状“闪烁”的色团，它可能模仿水柱中的光的波动，提供动态的遮挡或隐蔽。这两种类型的行为在科学文献中都没有描述。因此，产生和控制闪烁和闪烁的生色团信号是非常有意义的。该项目将通过对洪堡鱿鱼的现场视频观察和解剖分析(包括电生理学评估和外套膜组织的免疫组织化学分析)来增加我们对色团信号的了解。在项目过程中，将开发一种自动微光漂移相机组件的改进版本，它可以在中水深处操作，观察洪堡鱿鱼的自然行为，这些行为太小，无法携带Crittercam。斯坦福大学的研究生和本科生将从直接参与所有研究活动中受益，研究人员还将通过地区K-12计划、国际教育推广计划以及与主要公共媒体的合作，参与更广泛的公共科学传播努力。

Complex color-changing (chromogenic) behaviors in squid provide camouflage by mimicking benthic features such as rocks, coral or algae, and also serve in intra-specific signaling. However, few studies have been carried out under natural lighting conditions in the field, or without the presence of human observers or noisy remotely operated vehicles. This project will extend field studies of natural chromogenic behaviors to the family Ommastrephidae as exemplified by Dosidicus gigas (Humboldt squid). To accomplish the research under natural lighting conditions, the project will develop an improved low-light Crittercam and an improved Driftcam that can operate effectively at greater depths. These improved video platforms will lead to new understanding of the generation and regulation of camouflage and communication in the open-ocean environment. Little is known of predatory behavior in midwater region occupied by Humboldt squid, which in the eastern Pacific Ocean is associated with a vast volume of water that is naturally hypoxic called the oxygen minimum zone (OMZ). This OMZ is currently expanding and moving toward the surface, largely due to climate change. Observations of predatory activity in the upper OMZ will increase our understanding of how pelagic ecosystems might change as climate change progresses, and how these changes could impact economically and ecologically important species like the Humboldt squid.Chromogenic behavior in squid and other cephalopods is generated by muscular organs called chromatophores that are controlled by neural activity in the brain, and this direct, descending motor-control for chromatophores is unique to cephalopods. Pilot studies with the National Geographic Remote Imaging (NGRI) "Crittercam" video-package deployed on free-swimming Humboldt under natural lighting have revealed static patterning-type displays, like those seen in loliginid species, as well as a unique "flashing" behavior, with the entire body rapidly alternating between pale white and deep red. Flashing appeared to occur only during interactions with conspecifics, strongly suggesting a communication role. These data also revealed a more subtle wave-like "flickering" of chromatophores that may emulate fluctuations of light in the water column and provide dynamic countershading or crypsis. Neither type of behavior has been described in the scientific literature. The generation and control of the flashing and flickering chromatophore signals is therefore of great interest. This project will increase our knowledge of chromatophore signals through in situ video observations and anatomic analyses of Humboldt squid that include electrophysiology assessments, and immunohistochemical analyses of mantle tissue. An improved version of an autonomous low-light drift-camera package ("Driftcam") that can operate at midwater depths to observe natural behaviors of Humboldt squid that are too small to carry a Crittercam will be developed during the course of the project. Stanford graduate and undergraduate students will benefit from direct involvement in all of the research activities, and the researchers will also participate in wider public science dissemination efforts through regional K-12 programs, international educational outreach programs, and collaboration with major public media outlets.