Starting series of nature based sculpts

Decided to do a series of concept sculpts based on different fauna and flora belonging to various families of species classification in the real world (i.e aquatic, avian, mammalian, insect, herbivore, invertebrate...). This is the first; based on an aquatic mammal variant, kind of a plausible Darwinian off-shoot. Still haven't pinned down the final design but i'm leaning towards the top-most - seems to be more grounded in reality than the other two. Probably move onto something from the insect family next to complement my macro leanings of late.