Oh wonderful. You can bet that now, some of the less astute people that watched the show and didn't catch the "fiction" part of the credits, are going to be regaling everyone with "mermaids are real, I saw it on Animal Planet".
Sounds like instead of doing a proper job of presenting a serious scientific analysis of an alternate evolutionary possibility, stating from the outset that it was fiction - they decided to go the "National Enquirer" route and sensationalize it to boost ratings.
Animal Planet must be running short of ideas for programming. Seen the same thing happen with Discovery, History, Sci-Fi, etc - after a while, they run out of material and seemingly just throw anything on to fill the time slots and pull in viewers.