Not every day that one gets to read about narwhals. Wherever in the course of evolution did they make the decision to have those tusks! I include the link. Hope you can play the video - from another splendid BBC natural history series called "Nature's Great Events". Worth seeking out on DVD. Climate change threatens slow-swimming narwhalsMatt Walker, Editor, Earth News Narwhals are the 'marathon runners' of the oceans, scientists have discovered. The Arctic-living tusked whales are exceptional endurance athletes, possessing a greater density of slow-twitch fibres in their muscles than any other marine mammal studied.
But this ability also means they are one of the sea's slowest swimmers. That places them at high risk from climate change, as narwhals will not be able to cope with shifting, highly mobile ice floes caused by warmer seas...
http://news.bbc.co.uk/earth/hi/earth_news/newsid_8972000/8972021.stm
