Marine biologists study marine life and factors that impact marine life. They probably do it all the time, so I am not sure exactly what your teacher means by the “when” question. They study it at sea, at aquariums, in labs, under the ocean, etc. They use all the usual scientific methods to do it. They study marine biology because they are interested in it, like marine life, and because what happens with marine life has a huge impact on human life.

They make predictions about endangered species, the effects of pollution, the effects of over-fishing, the health of various species, expected results of conservation measures, etc. They observe the number of fish that are spawning, the number of fish caught, the size of fish caught, temperature of the ocean, etc.

Here are a few helpful sites.

life.bio.sunysb.edu/marinebio/becoming.html

www.career-descriptions.co.uk/marine-biologist-career-description.htm

www.indianchild.com/marine_biologist.htm

www.biologyreference.com/Ma-Mo/Marine-Biologist.html

Best of luck!☺

http://life.bio.sunysb.edu/marinebio/becoming.html

http://en.wikipedia.org/wiki/Marine_biology

http://www.soc.soton.ac.uk/PR/schools4.html