Actually, rabbit and hare are differentiated in Chinese as well. Rabbit is "兔子/T?zǐ," while hare is "野兔/Yět?."
Then for that matter: rabbit - 家兔 jiāt?; rat - 家鼠 jiāshǔ; field mouse - 田鼠 ti?nshǔ; common raven - 渡鴉 d?yā etc.
Point is, rabbit vs. hare, rat vs. mouse, crow vs. raven are not considered
basic categories in Chinese or Japanese. In everyday language, they are all considered variants of 兔 t? / usagi, 鼠 shǔ / nezumi and 鴉 yā / karasu. As a Chinese, when I see a rodent, I will think "鼠", and not think about whether it is a rat or a mouse.
Also the Danish mermaid in Chinese is 美人魚 měir?ny?, literally "beautiful woman fish". You can refer to a Danish mermaid as 人魚 in Chinese, but it sounds overly formal. The Chinese mermaid, which isn't an especially popular legend, is 鮫人 jiāor?n.
Enough of the derail. I'll talk about something more on-topic next.