Autotomy

Several families of lizard can voluntarily discard the tail when seized by a predator. This is known as autotomy. The discarded wriggling tail is thought to distract the attention of the predator, enabling the lizard to escape.

Lizards that are capable of autotomy have a vertical fracture plane through the body and part of the neural arch of the tail vertebrae. This is a plate of cartilage or connective tissue that develops after ossification. The vasculature supplying the tail immediately spasms when autotomy occurs, which stops any haemorrhage. If the tail is completely discarded, it cannot be reattached because to disruption to the blood supply of the tail. The animal is able to grow a new tail - growth normally begins after approximately one month, and is complete after approximately one to two years. The regenerated tail is never as long or well formed as the original and may have a slightly different scale colour and pattern.

In a clinical scenario, autotomy may occur when the lizard is being restrained. It is important to be prepared for (and try to prevent) this occurrence.

Autotomy and regeneration occur in many iguanid species but not in many agamids, monitors and chameleons.

Autotomy Learning Resources
Flashcards Test your knowledge using flashcard type questions	Reptiles and Amphibians Q&A 24

References

• Frye, FL & Williams, DL (1995) Self-Assessment Colour Review - Reptiles & Amphibians Manson