Super Seal Sense: Whisker movement strategies in Pinnipeds

主动触摸理论指出，传感器必须移动并参与特定于任务的行为，以提高感官任务的效率和性能。人类的指尖是一个活跃的触摸系统，因为他们做出有目的的、特定于任务的动作，例如，他们扫过纹理，触摸边缘来判断形状，挤压物体来判断硬度。大多数哺乳动物没有可移动的触觉指尖，而是有胡须触摸传感器。胡须是一种独特的感觉系统的一部分，具有高度的敏感性和可移动性。尽管许多研究人员认为胡须具有主动触觉功能，但从未在任何动物身上对其进行过定量研究。海豹、海狮和海象利用它们的胡须在黑暗和黑暗的水下栖息地觅食、导航和识别物体。它们的胡须是所有哺乳动物中最长、最敏感的，形状特殊，可以有目的地有系统地移动。海豹的胡须是起伏的，而海狮和海象的胡须是光滑的。这些形状的特殊性很可能会影响动物用胡须的感觉。然而，从来没有人对此进行过调查。在这项研究中，我将使用行为学实验、3D机械模型和机器人平台来描述海豹和海狮的主动触摸感知策略。我建议，对异形胡须的控制可以让海豹和海狮区分不同的物体。我将发现，主动控制胡须是否能够使它们更有效地感知，从而提高我们对主动感知、胡须机械和电机控制的理解。这将通过：1.描述海豹(波状胡须)和南非毛海豹(光滑胡须)中的胡须运动。动物将在水族馆里接受训练，完成3项不同的任务：蒙住眼睛，完成颜色、质地和大小，并从一系列不同的干扰物中选择目标物体。这些胡须将在水下被拍摄和跟踪，这样我就可以直观地看到在每个不同的辨别任务中胡须是如何移动的。在海豹和南非毛海豹中使用三种不同的辨别任务识别特定的胡须策略，如上所述。通过使用机械模型和机器人传感器研究沿胡须施加的不同力来估计胡须形状如何影响感觉。我预计胡须形状会影响胡须与物体接触时的弯曲程度。从博物馆标本中解剖出的海豹和海狮胡须将被扫描，并在专业3D软件(称为有限元分析)中进行建模，以查看对象在给定情况下的行为。4.探索不同形状的胡须(波状或光滑)如何影响运动策略。被解剖的羽足胡须将被连接到布置成口吻的机器人传感器上；机器人将做出动作来检测物体的大小和纹理。机器人的动作将与我的实验数据进行比较，看看海豹和海狮在感知方面的效率如何。这将通过结合解剖学、胡须跟踪、胡须机器人和详细的3D数字模型来提高我们对主动传感和胡须力学的理解。检查这些策略在水动力学任务(一些动物感知水运动的能力)过程中是否发生了变化。我的触觉任务将被调整为流体动力学任务，并将比较胡须和头部移动策略。

Active touch theory states that sensors must move and engage in task-specific behaviours in order to improve efficiency and performance in sensory tasks. Human fingertips are an active touch system as they make purposeful, task-specific movements, for example they sweep over textures, feel around edges to judge shape and squeeze objects to judge hardness. Most mammals do not have mobile, tactile fingertips and they have whisker touch sensors instead. Whiskers are part of a unique sensory system and are highly sensitive and moveable. Although many researchers assume whiskers do active touch sensing, it has never been quantitatively investigated in any animal. Seals, Sea lions and Walruses, use their whiskers for foraging, navigation and object identification in dark and murky underwater habitats. They have the longest and most sensitive whiskers of all mammals, that are specially-shaped and are moved systematically with purpose. Seal whiskers are undulating while sea lion and walrus whiskers are smooth. These shape specialisations are likely to affect what the animal can feel with their whiskers. However, no one has ever investigated this. For this fellowship I will characterise active touch sensing strategies in seals and sea lions using behavioural experiments, 3D mechanical models and robot platforms. I suggest that the control of specially-shaped whiskers allows Seals and Sea lions to discriminate between different objects. I will discover if actively controlling whiskers enables them to sense more efficiently, improving our understanding of active sensing, whisker mechanics and motor control. This will be tested by:1. Describing whisker movements in Harbor seals (wavy whiskers) and South African fur seals (smooth whiskers). Animals will be trained at SeaQuarium Rhyl to complete 3 different tasks: colour, texture and size while blindfolded and selecting a target object from a range of different distractors. The whiskers will be filmed underwater and tracked allowing me to visualise how whiskers move during each different discrimination task.2. Identifying task-specific whisker strategies in Harbor seals and South African fur seals using three different discrimination tasks as detailed above.3. Estimating how whisker shape effects sensation by investigating different forces applied along the whisker using mechanical models and a robot sensor. I expect whisker shape to affect the bend of a whisker when in contact with an object. Dissected seal and sea lion whiskers from museum specimens will be scanned and modelled in specialist 3D software (called Finite Element Analysis) looking at how an object behaves in a given situation. 4. Exploring how different-shaped whiskers (wavy or smooth) affect movement strategies. Dissected Pinniped whiskers will be attached to a robot sensor arranged like a muzzle; the robot will make movements to detect object size and texture. Robot movements will be compared to my experimental data to see how efficient seals and sea lions are at sensing. This will improve our understanding of active sensing and whisker mechanics, by combining aspects of anatomy, whisker tracking, whisker robotics and detailed 3D digital models.5. Examining if these strategies are altered during a hydrodynamic task (the ability of some animals to sense water movements). My tactile task will be adapted to a hydrodynamic task and whisker and head movement strategies will be compared.