Sastrugi breaking equipment—ripples and waves are often undercut and the surface is hard and unforgiving, with constant minor topographic changes between ridge and trough. The words "sastrugi" and "zastrugi" are Russian-language plurals; the singular is "sastruga" or "zastruga". The form "sastruga" started as the German-language transliteration of the Russian word заструга (plural: заструги). A Latin-type analogica singular "sastrugus" is used in various writings on exploration of the South Pole, including Robert Falcon Scott's expedition's diaries and Ernest Shackleton's "The Heart of the Antarctic". Under the action of steady wind, free snow particles accumulate and drift like the sand grains in barchan
Surface wave detection by animals The wave-detection system of "A lineatus" and other surface feeding fish is tuned to match the waves that signal prey in their environment. "A lineatus" feeds on aquatic, semi-aquatic and terrestrial insects, often insects that have just touched the surface of the water or have fallen in and are struggling at the surface. Abiotic sources give off capillary waves of frequency 8–14 Hz, while biotic sources give off much higher frequencies, anywhere from 12–45 Hz and above. This correlates well with "A lineatus’" peak sensitivity at higher frequencies. Wave stimuli are classified into two types: the first is click stimuli