Some lizards can lose part of their tail on purpose.
The behavior is called autotomy.
It is a defense system built around a simple trade:
Better to lose the tail than the entire lizard.
The tail can break at specialized points
In species that use autotomy, parts of the tail are built with weak zones.
When the lizard is grabbed or severely threatened, muscles can help separate the tail at one of those points.
The break is not random damage.
The anatomy is prepared for it.
Why does the detached tail keep moving?
Muscles and nerves inside the tail can continue producing movement for a short time after separation.
The wriggling tail attracts attention.
A predator may focus on it while the lizard escapes.
That is a pretty good use for equipment you have already decided to abandon.
Does the tail grow back?
Often, yes.
But the replacement is not usually identical to the original.
The regrown tail may contain cartilage instead of normal vertebrae and can differ in shape or color.
Regrowth also costs energy.
Why not drop the tail every time?
Because tails are useful.
They can help with balance, movement, fat storage, communication, or defense depending on the species.
That connects with the broader question of why animals have tails.
A lizard sacrifices something valuable only when the alternative may be worse.
Do all lizards do this?
No.
Tail autotomy varies widely among lizard species.
Some can do it readily.
Others cannot.
The exact mechanism and ability to regrow the tail also differ.
Is this anything like a snake shedding skin?
No.
Snakes shed their skin as part of normal growth and skin replacement.
A lizard dropping its tail is an emergency escape strategy.
The tail is expendable equipment.
If a predator grabs it, some lizards can leave it behind and keep running.
And that’s the short explanation.
Related explanations: Why do animals have tails?, Why do snakes shed their skin?, and Why do chameleons change color?