The tail is a vulnerable part of the body of animals in mope.io game. Thus, you should pay attention to it. Also, protect your tail carefully. In the October 18th update, tails were added. Small animals had no way to defend from the hunter before. All of the animals were utterly circular like the mouse. This is the tip that you can refer:
Tail-biting is also a game mechanic. This way helps players fight back by biting the enemy’s tail. If you can bite a tail, it will be highlighted with a light green outline. In mope.io game, the rabbit is the animal whose tail can’t be bitten by anybody on the map. The rabbit is neutral. When this happens, it will be counted as one bite and the prey will receive 40 XP + 2% of the bitten animal’s XP. However, this is difficult to occur because the predator is always aware of everything around.