Why is Earth called the Blue Planet? Because thereâ#x80;#x99;s so much water on the surface that the planet looks blue from outer space! Marine biology is the study of the plant and animal life in salt water environments, from microscopic plankton to the largest animal on earth, the blue whale. In Marine Biology: Cool Women Who Dive readers ages 9 to 12 explore the careers of three women who work within the science of marine biologyÂ#x97;Natalie Arnoldi, Ashanti Johnson, and Lauren Mullineaux. Nomad Press books in the Girls in Science series supply a bridge between girlsâ#x80;#x99; interests and their potential f.