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Ask Dr. Universe: Why do lizards lose their tails?

The crested gecko, like this one named Donna who lives at the Singapore Zoo in Singapore, is among the lizards that can lose its tail. Unlike the other lizards, the crested gecko’s tail will not grow back. (Wong Maye-E / AP)
The crested gecko, like this one named Donna who lives at the Singapore Zoo in Singapore, is among the lizards that can lose its tail. Unlike the other lizards, the crested gecko’s tail will not grow back. (Wong Maye-E / AP)

Q: Why do lizards lose their tails? – Bailey, Inwood, Iowa

Dear Bailey,

Our planet is home to all kinds of lizards. Maybe you’ve seen one climbing up the wall, scurrying through the grass or at the pet store. Just the other day, I saw a big green iguana when I visited the Washington State University Veterinary Teaching Hospital in search of an answer to your question.

Lizards hatch from eggs, have a backbone, scales and depend on the environment to keep warm. They have four legs and claws, and a tail, which they sometimes lose and grow back. My friend Marcie Logsdon was taking care of the big iguana and several other exotic animals. She told me all about lizard tails.

Lizards have a series of small bones that run down their back. They are called vertebrae. Along the tail are several weak spots called fracture planes, Logsdon said. They are the places where the tail can detach.

The main reason a lizard loses its tail is to defend itself. When a lizard detaches its tail, the tail whips around and wiggles on the ground.

Nerves from the lizard’s body are still firing and communicating with each other. In fact, sometimes the tail will keep moving for upwards of a half hour. This distracts a predator and gives the lizard plenty of time to escape.

When the lizard’s tail grows back, it’s a bit different than it was before. Instead of a tail made of bone, the new tail is often made out of cartilage, the same stuff that’s in your nose and ears. It can take quite a while for the cartilage to form, too.

The small green anole has a tail that is only about 4 inches long, but it takes about two months to grow back. Meanwhile, a longer iguana tail might take more than a year to grow back.

Most lizards can only lose their tails so many times before they can’t regrow them anymore. Of course, there are the exceptions. The crested gecko is one lizard that can lose its tail, but it doesn’t grow back.

Like lizards, some squirrels also lose their tails to escape predators. But their tails also don’t grow back. In nature, we see other animals that regrow different parts. Some worms split into pieces can grow into new individual worms. Sea cucumbers can do this as well. Some spiders can even regrow missing legs or parts of legs. Some salamanders can also shed their tails.

You know, tails can come in handy. Some lizards can wrap their tails around vines or branches. Others use their tails as a kind of propeller to help them move through the water. Tails are also useful for balance. And for some lizards, being able to ditch their tail might just save their life.

Sincerely,

Dr. Universe

Ask Dr. Universe is a project from Washington State University. Submit a question of your own at http://askDrUniverse.wsu.edu/ask.


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