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 to these by swimming 15 cm. The neuro-anatomical basis for this ability has not yet been identified. "A lineatus" and similar surface feeding fish (e.g. "Pantadon bucholzi") use a slightly modified lateral line organ called a neuromast to detect surface waves. "A lineatus" has 18 neuromasts (specialized vibration-sensitive lateral line organs) on the dorsal surface of the head of "A lineatus". These are organized into three groups by longitudinal position, and each group is bilaterally symmetric. The groups are, caudal to rostral: nasal/infraorbital (I), supraorbital (II), and supratemporal/post-orbital (III). Each neuromast is a cluster of hair-cell bundles arranged in a