Sastrugi Sastrugi Sastrugi, or zastrugi, are sharp irregular grooves or ridges formed on a snow surface by wind erosion, saltation of snow particles, and deposition, and found in polar and open sites such as frozen lakes in cold temperate regions. The ridges are usually perpendicular to the prevailing winds; they are steep on the windward side and sloping to the leeward side. Smaller irregularities of this type are known as ripples (small, ~10 mm high) or wind ridges. Larger features are especially troublesome to skiers and snowboarders. Traveling on the irregular surface of sastrugi can be very tiring, and can risk
Surface wave detection by animals animal will wait a small amount of time (typically <1s) before initiating a response towards the prey, should the surface waves perceived fall within the preferred stimulus range. Response towards prey typically follows the pattern orientation towards prey, swimming towards prey, and then prey capture. This ability is sometimes referred to as a sense of “distant touch.” Several species have been shown to use surface wave detection for prey capture. Among these are many species of freshwater fish, notably the groups hatchetfish (Gasteropelecidae), freshwater butterflyfish (Pantodontidae), halfbeaks (Hemiramphidae) and killifish (Aplocheilidae)(list from ). For its consistently stellar performance at the