Lizards losing their tails is a fascinating phenomenon in the animal kingdom. As a lizard owner or wildlife enthusiast, you may have wondered – does it hurt when lizards lose their tails? If you’re short on time, here’s a quick answer to your question: Yes, there is some evidence that lizards can feel pain when they lose their tails, but it does not seem to be an intensely painful process for them.
In this article, we’ll take an in-depth look at lizard tail loss, also called autotomy. We’ll explore lizard tail anatomy, how the tail detaches, and what science says about pain and nerve connections in discarded lizard tails.
Lizard Tail Anatomy
Vertebrae
A lizard’s tail contains many small bones called vertebrae that give it flexibility and allow it to move in different directions. The vertebrae are connected by flexible joints and ligaments that act like hinges, allowing the tail to bend and twist.
Most lizards have between 50-150 vertebrae in their tails, depending on the species. The vertebrae towards the base of the tail near the lizard’s body are larger and more robust. They help anchor the tail muscles and support the weight of the tail.
Further along the tail, the vertebrae become smaller and more numerous, increasing flexibility.
Blood Vessels
A network of blood vessels runs through the core of the tail, bringing oxygen and nutrients to the tissues. When a lizard loses its tail, specialized muscles at the breakage point constrict these blood vessels to limit blood loss.
Cauterization of the severed blood vessels also helps stop the bleeding. Some lizards, like leopard geckos, have connective tissue partitions inside their tail that limit blood flow between different tail segments.
This helps restrict blood loss to only the detached portion of the tail if it breaks off.
Muscles
Bands of muscles surround the vertebrae and blood vessels, allowing the lizard to move its tail in different directions. Longer muscle segments spanning several tail vertebrae control larger movements and positioning of the tail.
Smaller muscle groups between each vertebra control more precise movements. These tail muscles receive signals from motor neurons that run through the core of the tail. Specialized tail muscles also allow some lizards like chameleons to grip branches with their tail for extra stability.
When the tail detaches, these muscle groups are severed, which is why the detached tail continues to writhe around for a short period.
How Tails Detach
Fracture Planes
Lizards have special fracture planes in their tails that allow the tail to detach easily. These fracture planes are made up of connective tissue and are located between the vertebrae in the tail. When the lizard is grabbed by a predator or faces danger, muscles in the tail rapidly contract, which causes the tail to break off right at the fracture plane.
This allows the tail to detach quickly and cleanly, leaving a severed tail behind while the lizard escapes.
Muscle Contractions
The main way a lizard’s tail detaches is through extremely strong muscle contractions. Lizards have vertically oriented muscles that connect each vertebra in their tails. When sensing danger, the lizard contracts these muscles very forcefully, which causes the fracture plane between vertebrae to fail, severing the tail.
Researchers have found these muscle contractions are so strong that they are equivalent to 100 times the force the muscles exert during normal movement! This super contraction is what allows the tail to pop off so easily.
Cauterization
An amazing fact about lizard tail loss is that the tail immediately cauterizes after detaching. This means tissues are sealed by a chemical burning process to stop blood loss. Special blood clotting agents are released from the severed tail end that mix with the blood to cause rapid clotting.
The spinal cord in the tail also constricts to prevent bleeding. Cauterization allows the lizard to lose its tail quickly without risk of bleeding out. It’s an ingenious protective mechanism built into lizard bodies to help them survive predator attacks and other dangers in the wild.
Nerves and Pain Sensation
Nerve Connections
Lizards have a complex nervous system that allows them to sense and respond to stimuli in their environment. Their spinal cord and nerves extend into their tail, allowing for sensory input and motor control. When a lizard’s tail is detached, these nerve connections are severed.
However, the lizard’s nervous system is designed to minimize neurological damage from tail loss.
Specifically, lizards have superficial sensory nerves that run laterally across each tail segment. Deeper in the tail, motor nerves control muscle contraction and relaxation. When a predator grabs the lizard’s tail, the weaker superficial sensory nerves detach more easily than the deeper motor nerves.
This allows the lizard to drop its tail quickly before major nerve damage occurs.
Pain Receptors
Lizards do have specialized pain receptors called nociceptors that sense potential tissue damage. However, lizards seem to have a higher pain tolerance than humans. Their nociceptors may not fire as readily in response to tail injury or detachment.
Additionally, lizards likely experience less pain due to rapid vasoconstriction when the tail detaches. Vasoconstriction reduces blood loss but also decreases inflammation that can cause pain. Furthermore, the severed tail may release endogenous opioids that block pain signals.
Tail Movement
When a lizard’s tail first detaches, it exhibits unusual and complex movement patterns such as writhing, flipping, and wriggling. What drives this phenomenon?
Researchers have found that the motor nerves in the severed tail continue firing after detachment, stimulating muscle contractions. However, without sensory nerves signaling position, the tail muscles contract randomly.
These unpredictable motor patterns give the impression of complex controlled movement.
The vigorous tail activity likely draws the predator’s attention away from the escaping lizard. Most tail movement ceases within 60 minutes as residual muscle energy stores deplete and nerves become completely inactive.
Healing and Regeneration
Open Wound
When a lizard loses its tail, it leaves behind an open wound where the tail broke off. This wound is prone to infection and needs to heal quickly. To facilitate healing, the lizard’s body triggers blood clotting and tissue regeneration mechanisms at the wound site (Gilbert et al., 2013).
The open wound seals within a day or two as new tissue forms over it. This seal prevents further blood loss and protects the wound from infections as the healing process continues (Hutchins et al., 2017).
Scarring
Lizards can regenerate complex body parts like tails because their healing results in minimal scarring. Mammals form thick collagen scars when wounded, which blocks regeneration. Lizards, in contrast, have refined wound healing that allows cell regrowth without extensive scarring (Simkin et al., 2015).
When a lizard loses its tail, the wound heals with little collagen deposition. Instead, cells called blastema cells multiply at the wound site and facilitate regeneration of the lost tail (Hutchins et al., 2017).
New Tail Growth
Within days after a lizard loses its tail, a growth called a regeneration blastema forms at the wound site. This mass of stem-cell-like cells then starts regenerating the lost tail through rapid cell division and specialization.
Cartilage tubes form first to make the tail’s basic structure, followed by muscle, blood vessels, and scales. The new tail reaches full length in 2-3 months. It looks similar but isn’t an exact replica of the original.
The regenerated tail often lacks segments and scales and has a rod of cartilage rather than vertebrae (herpcenter.com).
Tail regeneration capacity varies between lizard species. Gecko and basilisk lizards can regrow an exceptionally intricate original-like tail while iguanas regenerate only a short cartilage spike (AMNH).
Tail loss impact also differs – arboreal geckos with prehensile tails are severely disadvantaged without their grip aid (Zhang et al., 2008).
Conclusion
In conclusion, the current research suggests that lizards do likely feel some degree of pain when losing their tails, but it does not appear to be an intensely painful process for them. The tail has evolved to detach easily, and neural connections are limited.
While we cannot definitively prove the subjective pain experience in lizards, studies point to mild to moderate pain sensation followed by rapid healing. Hopefully this article gave you some deeper insight into the anatomy and science behind lizard tail loss!
