Source: http://deepseanews.com/2014/04/why-do-be...

Unlike many dolphins and whales, belugas lack a dorsal fin. Maybe it’s too cold to have blood running through such a thin exposed surface, or maybe it’s too dangerous to swim under ice with a dorsal fin. Whatever the reason, belugas are apparently making up for this absence with fat. Getting ready for a risky maneuver? Time to pooch the paunch. In the ever changing ice flows these whales call home, the extra stability these love handles provide may mean the difference between a clean getaway and a collision with an iceberg.