Almost all of the American ones I've heard of are terrifying.

The chick, in this context.

The Boto-cor-de-rosa, or river dolphin, is a real animal

But the cryptid of the same name is a river dolphin that is actually a shapeshifting trickster, who will turn himself into an attractive man (often depicted wearing a fancy hat to cover the blowhole atop his head) and seduce and bang women.