Survivors: Intertidal Zonation
An organism's preference for the habitat to which it is adapted creates a mosaic of similarly adapted organisms clumped in recognizable bands along the shore. This is a phenomenon known as intertidal zonation.
Survivors: Predators and Prey
The ocean provides home to a dazzling variety of life. Yet there was a time when early life forms faced a multitude of struggles that threatened their ability to survive. The evolution of adaptations to overcome these challenges enabled life to endu...
Survivors: The Oxygen Revolution
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...
Survivors: Survival in the Intertidal Zone
Perhaps nowhere on Earth is the ability to survive better demonstrated than that part of the shore alternately exposed and submerged by tides-a region known as the intertidal zone. Remarkably, marine organisms there have evolved a multitude of ways ...
Survivors: Long-Term Survivors
Despite the challenges of long-term survival on Earth, some phyla-including sponges, jellyfish, arthropods and mollusks-have endured for hundreds of millions of years, even in the most extreme environments.
Survivors: Early Invertebrates
The first animals on Earth were invertebrates-animals without backbones-and they diversified rapidly in the geologic period known as the Cambrian.