Why do lizards lose their tales?

John Grundy News, Revealing Reptiles


The old distraction trick

Common lizards and Slowworms share a defence mechanism called “autotomy,” with many other species of lizard around the world. Simply put, they are able to release their tail when they are threatened by a predator. The tails often draw a predator’s attention, by moving vigorously as a distraction. Though this is a natural form of defence, it is still stressful for the lizard.

Underside of lizard tail showing fracture lines.

How It Happens
Lizards that can drop their tail have “fracture planes” spaced regularly down the length of the tail. Skin, muscles, blood supply, nerves, and bone separate when the tail is dropped. People often think the reptile tail drops as a result of being picked up. Often without even being handled a startled lizard can launch its tail off without any physical contact. Slow worms seem to do this very readily.

What Effects It Has
Tail loss can affect the lizard. Sense of balance, climbing or walking regularly could be a problem.Lizards store a certain amount of fat in their tail. These fat deposits are critical, especially approaching Winter, when fat reserves can mean life of death during brumation. Juvenile lizards stop growing while the tail is regenerating, and, in adults, the reproductive processes stop. Healing and regenerating takes energy, so lizards that have dropped their tail can suffer from nutritional deficiencies. Losing their tail can make a lizard more susceptible to predators, as it no longer has anything to drop if it is caught to give itself time to escape.

Regrowth can take several months and the new tail is never the same as the original. Colouration is diminished and the length is reduced. You can always spot a lizard or slowworm that has a re grown tail.

Recently lost tail. Healed over. Regrowth will begin once the stump has calloused.

 

John R Grundy

Revealing Reptiles Project Officer

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