Originally Posted by
Mod
Many bizarre and undiscovered species? A certainty.
Mermaids? Very nearly impossible. Assuming you mean fish trunk and human torso+, if they existed, we'd have found (and co-existed or killed them) by now.
-Culturally speaking, humans and humanoids are social animals, they would naturally try to interact or war with us.
-Scientifically speaking, unless they only look human up top, but under the skin are whack ass different, it's not possible for their half-human anatomy to sustain life primarily in the water. They lack the physiology to swim, float, and be a competitive species at sea.