A challenge to traditional (pre-1860) ideas about species came from embryology, when it was discovered that embryos of dissimilar organisms, such as sharks and humans, resemble each other. Embryology involves the study of the formation and the development of an embryo and the fetus. It is one type of evidence of evolution such that the embryos of many different kinds of animals, mammals, reptiles, birds, fish among others, are similar showing a common ancestry.
<span>Lakes and ponds are inland bodies of standing or slowly moving water. Although lakes and ponds cover only 2 percent of the world's land surface, they contain most of the world's fresh water. Individual lakes and ponds range in area from a few square meters to thousands of square kilometers. In general, ponds are smaller than lakes, though regional idiosyncrasies of naming abound—Henry David Thoreau's famous Walden Pond in Massachusetts has a surface area of 64 acres. Lakes and ponds are an important source of fresh water for human consumption and are inhabited by a diverse suite of organisms.</span>
I think it might be <em>natural disasters.</em>
The kind that messes everything up I guess
