A marine biologist studies aquatic creatures and their interactions with their environments. Biological oceanography and the related sciences of chemical, physical and geological oceanography are studied by marine biologists in order to gain a better understanding of the marine animals. The study of marine biology, like all scientific fields, follows the scientific process. The ultimate purpose of science is to discover the truth. Research is usually conducted rationally and in a systematic manner to reduce the unavoidable margin of error inherent in any scientific study and to minimise the researcher's bias. In scientific inquiry, observations are the most important part of the process. Once hypotheses have been formulated and validated, they can be accepted or rejected based on a number of observations. Experiments are typically used to test hypotheses that can be predicted from the original findings.