Lizards with vibrant blue tails are striking due to their visual contrast. This distinctive coloration is a remarkable adaptation found in various species across different environments. The blue tail often serves purposes integral to the lizard’s survival and interactions within its ecosystem. Exploring this unique trait reveals insights into the diverse strategies these reptiles employ.
Lizards Commonly Featuring Blue Tails
Several lizard species are recognized for their prominent blue tails, particularly during their juvenile stages. The American Five-lined Skink (Plestiodon fasciatus) is a common example found throughout the eastern United States and parts of Canada. Juveniles of this species display a black or dark brown body with five distinct yellowish or white stripes and a bright metallic blue tail. As these skinks mature, the blue tail color often fades, especially in males, turning to a gray or brownish hue.
The Western Skink (Plestiodon skiltonianus) also exhibits a vibrant blue tail when young, alongside broad stripes on its back. This species is prevalent in the western United States and parts of British Columbia. Both American Five-lined Skinks and Western Skinks are ground-dwelling lizards that prefer moist, wooded areas and often bask in the sun.
Another species, the Christmas Island Blue-tailed Skink (Cryptoblepharus egeriae), is native to Christmas Island, Australia. These skinks have a dark black body with bright yellow stripes, and females often retain their blue tails throughout their lives. The Italian Wall Lizard (Podarcis siculus), while usually green or brown, can also show hints of blue on its tail, especially in some island populations. This species is native to southern and southeastern Europe but has been introduced elsewhere.
The Evolutionary Role of a Blue Tail
The striking blue coloration of a lizard’s tail primarily serves as a defense mechanism against predators. This bright color acts as a decoy, drawing a predator’s attention away from the lizard’s more vulnerable body and head. When threatened, many lizards can shed their tails, a process known as caudal autotomy. The detached tail continues to wriggle, distracting the predator and allowing the lizard to escape.
The blue coloration, particularly its reflection of ultraviolet (UV) light, is effective against predators like snakes, which are sensitive to UV light. This strategy is common in diurnal, ground-dwelling species where camouflage is less effective. While predator distraction is a primary function, the blue tail also plays a role in intraspecific communication, such as signaling juvenile status.
Tail Regeneration and Coloration Changes
When a lizard sheds its tail through caudal autotomy, it can regenerate a new one. This process involves the formation of a blastema, a mass of cells that forms the new tail. However, the regenerated tail is typically not an exact replica of the original.
The new tail often has anatomical differences, such as a single tube of cartilage instead of segmented vertebrae, and longer muscle fibers. These differences can make the regenerated tail less flexible. Importantly, the regenerated tail frequently differs in coloration from the original. It may be less vibrantly colored, duller, or take on a gray, brown, or even black hue, rather than the bright blue. This change in color is often due to variations in tissue and pigment cell development.