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 Chinese dialect of northern Fujian is a minimal example. With the exception of , which is often merged with the zero initial, the initials of this dialect are present in all Chinese varieties, although several varieties do not distinguish from . However, most varieties have additional initials, due to a combination of innovations and retention of distinctions from Middle Chinese: Chinese finals may be analysed as an optional medial glide, a main vowel and an optional coda. Conservative vowel systems, such as those of Gan dialects, have high vowels , and , which also function as medials, mid vowels and ,