Animals (or people) with bits of themselves missing, symbolise something quite profound.

Wisdom comes at a price, in that we either have to give something up in order to get it, or we get it having lost bits. In many old Celtic legends, there is a common theme of people suffering physical injury on their first successful journey to the otherworld (sometimes called the underworld). Odin, from the Norse pantheon, paid for the knowledge of the runes with one of his eyes for example. There's a chap in the Irish Celtic legends (I think it might have been Taliasin or something - I can't remember, its a long time since I read the story), that made it unharmed to the underworld, but got trapped there. He was rescued by an eagle, which he then allowed to take nourishment from his leg (by biting a chunk of flesh off) as payment.

Of course these are all legends, and should be taken with a pinch of salt, but the message/symbolism is valid. Its hard to deny that in the 'conventional' reality, the price of wisdom is that we have to give up our youth. I.e. we spend so long learning that by the time we know even a bit, we're getting on in years.

Of course a lizard without its tail could simply be a lizard that got caught by a cat or a bird, but specifically noticing it is relevant in itself.