Other substances are being tested by drug companies as possible treatments for arthritis and various types of cancer, including leukemia. Marine biologists have used marine animals in experiments to increase our knowledge of human life processes. For example, much of our understanding about the early developmental states of organisms has come from the study of marine animals. Marine biologists also have used the squid's giant nerve fibers to discover how nerves work. The squid's nerve fibers are so large that scientists can place instruments inside different parts of the nerve to record mechanical, chemical, and electrical responses.
Many marine biologists do much of their work in special laboratories near seacoasts.
Seawater is readily available there to maintain organisms for research. Biological oceanographers usually focus on the open ocean and deepwater regions of the oceans. In addition to studying the ocean's organisms, they investigate the physical and chemical nature of the ocean, including its temperature, salt content, and oxygen content. For example, they try to learn how sunlight, nutrients, and temperature in the sea affect the growth rate of the mass of tiny plantlike marine organisms known as phytoplankton. Understanding how food webs function is important in determining how many fish can be harvested in different regions of the oceans.