Its heart alone is as large as a small car. Blue whales are an overall blue-gray color, mottled with light gray. Cold water diatoms adhere to their skin and sometimes give their bellies a yellowish tinge, giving the blue whale its nickname of “sulfur bottom.” Blue whales are long and streamlined.
: http://www.marinemammalcenter.org/education/marine-mammal-information/cetaceans/blue-whale.html

