While fishes are the most successful and abundant marine vertebrates, marine reptiles represent the fewest number of species and individuals. Marine birds probably evolved from reptiles and are generally considered to be among the most highly specia...
At one time, Earth's atmosphere had a far smaller percentage of oxygen than it does today. Only when that percentage began to rise, thanks to the oxygen production of photosynthetic plants and organisms, was it possible for animals to come into bein...
From its likely role in the formation of life, to its impact on global climate, the world ocean has shaped planet Earth to an extent that is almost impossible to overstate. Perhaps the best way to fully grasp the enormity of the ocean's impact is to...
There is no definitive evidence that proves beyond a doubt where water originated. But wherever it came from, water did eventually cover more than two-thirds of Earth's surface. The implications of this for the formation of life on planet Earth were...
At one time, Earth was a very different planet than it is today. Its atmosphere, in particular, bore very little resemblance to the one that we depend on for the air we breathe. It probably consisted primarily of carbon dioxide and nitrogen gas.
Many scientists believe that life on Earth began in the ocean, because continental areas on the early Earth did not offer the kind of conditions that would have been conducive to life.
The third planet out from the sun, Earth is unique in many ways. But perhaps the most significant is that seventy percent of Earth's surface is covered with water.