Marine Biology: A Very Short Introduction looks at marine life and marine processes. The marine environment is the largest, most important, and most mysterious habitat on our planet. It contains more than 99 percent of the world's living space, produces half of its oxygen, plays a critical role in regulating its climate, and supports a remarkably diverse and exquisitely adapted array of life forms. As the 21st century progresses, human activities such as overfishing, coastal development, plastic pollution, oil spills, nutrient pollution, the spread of exotic species, and the emission of climate changing greenhouse gases are posing a significant threat to the marine environment and to many of its life forms.