Leatherback sea turtle the offspring with any special advantages. While other sea turtle species almost always return to their hatching beach, leatherbacks may choose another beach within the region. They choose beaches with soft sand because their softer shells and plastrons are easily damaged by hard rocks. Nesting beaches also have shallower approach angles from the sea. This is a vulnerability for the turtles because such beaches easily erode. They nest at night when the risk of predation and heat stress is lowest. As leatherback turtles spend the vast majority of their lives in the ocean, their eyes are not well adapted to
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 ,