The current thinking of why mammals live in the sea is based on the hypothesis that mammals evolved on land and marine mammals are a lineage of mammals that returned to the sea.  Please watch the PBS video found at the following link:

http://www.pbs.org/wgbh/evolution/library/11/2/e_s_3.html

or

https://www.youtube.com/watch?v=ewtw_nZUIDQ

Evolution is still a controversial subject in the States (not so much in Europe). What do you think? Provide at least 2 references to support your opinion. (Please note that The Bible is not a scientific reference, there is research there if that is the route you take.)

The current thinking of why mammals live in the sea is based on the hypothesis that mammals evolved on land and marine mammals are a lineage of mammals that returned to the sea.  Please watch the PBS video found at the following link:

http://www.pbs.org/wgbh/evolution/library/11/2/e_s_3.html

or

https://www.youtube.com/watch?v=ewtw_nZUIDQ

Evolution is still a controversial subject in the States (not so much in Europe). What do you think? Provide at least 2 references to support your opinion. (Please note that The Bible is not a scientific reference, there is research there if that is the route you take.)