Sea turtle migration Studies of loggerhead and leatherback hatchlings have shown that moonlight reflected from the sea is an important visual cue in guiding movement from the beach to the sea. This navigational mechanism becomes a handicap if nesting sites are affected by artificial lighting since this can mean that hatchlings head towards the artificial lights rather than offshore towards the moonlit sea. Hence, the use of moonlight by turtle hatchings as a navigational cue can be considered an 'evolutionary trap'. Loggerhead and green turtles can detect the orbital movement of waves and use this information to swim perpendicular to the waves crests.
Varieties of Arabic sedentary varieties and the rural varieties within the Arabian peninsula are even more conservative than those elsewhere. Within the sedentary varieties, the western varieties (particularly, Moroccan Arabic) are less conservative than the eastern varieties. A number of cities in the Arabic world speak a "Bedouin" variety, which acquires prestige in that context. When it comes to phonetics the Arabic dialects differ in the pronunciation of the short vowels (, and ) and a number of selected consonants, mainly , and the interdental consonants , and , in addition to the dental . Emphasis spreading is a phenomenon where is backed