Vision for navigation: What can we learn from ants?

The visual systems of all animals are used to provide information that can guide behaviour. In some cases insects demonstrate particularly impressive visually-guided behaviour and then we might reasonably ask how the low-resolution vision and limited neural resources of insects are tuned to particular behavioural strategies. Such questions are of interest to both biologists and to engineers seeking to emulate insect-level performance with lightweight hardware. One behaviour that insects share with many animals is the use of learnt visual information for navigation. Desert ants, in particular, are expert visual navigators. Across their foraging life, ants can learn long idiosyncratic foraging routes. What's more, these routes are learnt quickly and the visual cues that define them can be implemented for guidance independently of other social or personal information. Here we review the style of visual navigation in solitary foraging ants and consider the physiological mechanisms that underpin it. Our perspective is to consider that robust navigation comes from the optimal interaction between behavioural strategy, visual mechanisms and neural hardware. We consider each of these in turn, highlighting the value of ant-like mechanisms in biomimetic endeavours.     

Navigating Between Treaties and Tweets:How to Ensure Discourse about Maritime Freedom Is Meaningful

In contemporary international discourse about maritime freedom (e.g., “freedom of navigation”), nations often speak in generalities, but rarely clarify what they mean. To reduce the risk of misunderstanding, nations should navigate their use of language between two purposes simultaneously. First, any discussion should be concise, communicable, and comprehendible. Additionally, nations should also be prepared to dialogue on these matters in greater depth and detail, and any substantive discussion should be faithful to the applicable international law that binds nations. A way to ensure such discourse is meaningful is by following a three-step process of labeling, framing, and applying. This article details this approach.     

Behavioral analysis of polarization vision in tethered flying locusts

For spatial navigation many insects rely on compass information derived from the polarization pattern of the sky. We demonstrate that tethered flying desert locusts (Schistocerca gregaria) show e-vector-dependent yaw-torque responses to polarized light presented from above. A slowly rotating polarizer (5.3° s^–1) induced periodic changes in yaw torque corresponding to the 180° periodicity of the stimulus. Control experiments with a rotating diffuser, a weak intensity pattern, and a stationary polarizer showed that the response is not induced by intensity gradients in the stimulus. Polarotaxis was abolished after painting the dorsal rim areas of the compound eyes black, but remained unchanged after painting the eyes except the dorsal rim areas. During rotation of the polarizer, two e-vectors (preferred and avoided e-vector) induced no turning responses: they were broadly distributed from 0 to 180° but, for a given animal, were perpendicular to each other. The data demonstrate polarization vision in the desert locust, as shown previously for bees, flies, crickets, and ants. Polarized light is perceived through the dorsal rim area of the compound eye, suggesting that polarization vision plays a role in compass navigation of the locust.     

Multisensory Control of Orientation in Tethered Flying Drosophila

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