The Tails of an animal is an important body part, due to its vulnerability. It is recommended for all animals, even the largest ones, to keep their tails well-guarded, for the reasons below. Every animal except the Mouse, Shrimp, Chipmunk, Trout and Crab should watch their tails, these exceptions being due to said animals not having tails vulnerable to a tail-bite.
Tail-Biting is a game mechanic that allows a prey animal to fight back by biting the tail of a predator. If a tail is bite-able, it will be highlighted with a light green outline. The only animals without a bite-able tail are the Rabbit, Trout. Arctic Hare, Mouse, Shrimp, Chipmunk, Lemming, Snail, and Crab. Animals that are neutral (with a dark green outline) cannot have their tails bitten, unless they are tier 15 or above.
When it occurs - although uncommon if a predator is at least somewhat aware of their surroundings - it counts as one bite and the prey gets 40 XP + 2% of the bitten animal's XP, said to be with a maximum of double the biter's current XP, even though there really is no maximum.For example, assume a Rabbit that has 200 XP bites a Zebra that is less than 2K XP away from reaching Cheetah. When the rabbit bites it, the Zebra loses 400 XP(40+360(18000*0.02)), and the Rabbit immediately becomes a Fox, because it has 600 XP. The fox cannot bite tails for 3 seconds, due to upgrade invulnerability. If it were to bite 2 more times, then it would gain about 750 XP. Then, if it bites one more time, it immediately becomes a Zebra, about 1K away from Cheetah. A common strategy is for a small animal to wait until a predator is busy with other large creatures, then tail-bite it and run, gaining enormous amounts of XP for it's size.
- Some animals appear to have huge tails, but only a small part can be bitten. The longest tail is the Blue Whale’s, and one of the shortest tails is the Jellyfish's (with no visible tail at all).
- Tails were added on the October 18th update, which has been dubbed by the developer as the 'Tails Update'.
- Before this, animals had absolutely no way of defending themselves against a predator, other than abilities and running.