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 (short bursts of amplitude less than 100μm which contain many frequencies between 5 Hz and 190 Hz and are of short duration, as when an insect just touches the water rather than moves continuously at the surface). The other is continuous wave stimuli, which will contain many frequencies and in the wild are generated by fallen prey struggling at the water surface. It has been pointed out that "A lineatus" and other surface feeding fish are able to locate prey even if the waveform is only in click form (just touching the surface once, as when surfacing for air or