Why does a five-lined skink drop its own tail?

A young five-lined skink carries a decoy. Its body is black with yellow stripes, and its tail is a bright, unmissable blue. A 2021 review describes bright juvenile tails in this skink’s genus as decoys that draw attacks away from the body, and that is the point. The Missouri Department of Conservation says that when a predator seizes the tail, it breaks off easily, the lizard loses very little blood, and the dropped piece keeps wiggling while the skink slips away.

The trick is called autotomy, which means an animal sheds part of its own body on purpose. It sounds like a design flaw, but it is a deal: the lizard pays with a tail and keeps its life. Skinks run the deal often. The Animal Diversity Web, a University of Michigan database, lists a long line of possible attackers, from crows and kestrels to raccoons, opossums, snakes and house cats.

This article covers how the break works, why the tail is blue, how a new one grows, and what the swap costs. Some of the best evidence comes from other lizards, and we flag that each time.

Meet the five-lined skink

The five-lined skink (Plestiodon fasciatus) is a small lizard of eastern North America. The Reptile Database notes that it was long called Eumeces fasciatus, and that the move to the genus Plestiodon dates to studies from 2004 and 2005. It likes moist, partly wooded places with plenty of hiding spots, and the Animal Diversity Web says many live in disturbed edge habitats, including around building foundations. Some even live among driftwood on Great Lakes beaches.

Egg counts are a small place where sources differ: the Animal Diversity Web gives 15 to 18 eggs per clutch, and the Missouri Department of Conservation gives 4 to 14. Local populations may simply differ, and we do not know which figure fits where you live.

A tail built to break

A tail drop is not a rip. It is a planned release. A 2021 review of lizard tail regeneration by James Barr, Catherine Boisvert and Philip Bateman explains that many lizards have pre-formed weak points in their tail vertebrae. When the lizard is threatened, it contracts its tail muscles to shed the tail. Right afterward, small valves in the tail’s arteries squeeze shut to limit bleeding. That matches the Missouri Department of Conservation’s note that a skink loses very little blood.

The dropped tail keeps twitching. The Animal Diversity Web and the Missouri Department of Conservation both say this distracts the predator. A hungry raccoon or kestrel is left holding something that moves like prey, while the actual prey is already under a log. The lizard also has other defenses: the Animal Diversity Web says skinks bite attackers and seek crevices.

Why the tail is blue

The blue tail of a hatchling is not decoration. The 2021 review says juvenile Plestiodon tails are often brightly colored and act as decoys, which makes quick regrowth matter for these species. If a predator aims at the brightest thing on the animal, the best thing to lose is the tail.

There is a second idea. The Missouri Department of Conservation says the bright juvenile markings may also protect young skinks from territorial adult males, who might otherwise attack them. The sources we read do not say which idea is stronger, and the two are not rivals. The color may do both jobs.

The blue does not last. The Animal Diversity Web says the tail color dulls with age, that females keep it longer than males, and that adult males end up with gray tails.

How the tail grows back

Regrowth starts fast. The 2021 review describes a blood clot forming, then skin cells crawling over the wound, then a growth zone called a blastema, which forms within about 10 to 15 days in lizards generally. The new tail lengthens from there.

It is an imperfect copy. The review says the regrown tail is supported by a ridged, semi-ossified cartilage tube instead of separate vertebrae. The Missouri Department of Conservation says the new tail is shorter and drab gray. It still does much of the old tail’s job, though not all of it.

How fast? The review lists regrowth rates for 56 species, from 0 to 4.3 millimeters a day. As we read one table in it, juvenile five-lined skinks grew new tail at about 0.39 to 1.14 millimeters a day. We could not double-check that figure in a second source, so treat it as a rough range.

What this looks like in practice

Here is the sequence from the sources, step by step.

For example, take that rough rate range of 0.39 to 1.14 millimeters a day. A centimeter of new tail would take roughly 9 to 26 days. That is our own arithmetic, not a measured result, and real rates change with temperature, food and age.

What the swap costs

Regrowth is not free. The 2021 review says it takes a large energy investment, raises metabolism and can use up fat reserves, and that some lizards run slower and act more cautiously while it happens. Evidence for five-lined skinks specifically is thin in the sources we read, so the best numbers come from other species.

One of them is a 7-year field study of the green-spotted grass lizard in Taiwan. The authors found that tail loss lowered monthly survival, especially for breeding males: 0.47 for tailless males in the breeding season, against 0.81 for intact ones. Once the tail had regrown, survival returned to roughly the level of lizards that never lost one. The authors suggest the cost came from how the body spends its resources, not from extra attacks. A different lizard in a different place may not behave the same way, but it shows that “just a tail” can be a big price.

Common mistakes and myths about tail loss

Myth: the tail just tears off. The break happens at built-in weak points, with muscle action and valves that limit bleeding. It is controlled by the lizard, not an accident.

Overstated: the new tail is as good as the old one. It is shorter and grayer, and its core is cartilage instead of bone-like vertebrae. It works, but it is not the original.

Mistake: tail loss is free. The energy and survival data above say otherwise.

Mix-up: any blue-tailed lizard is a five-lined skink. Several close relatives look alike. The Reptile Database names Plestiodon inexpectatus and Plestiodon laticeps in a comment on this species’ lost type specimen, and says the history of the name is tangled. Pinning down which skink you are looking at can take more than counting stripes.

Too narrow: shedding a tail is the only lizard escape. The Common basilisk escapes by running across water, and the Tokay gecko is better known for clinging to walls. For regrowth on a much bigger scale, see the Axolotl, a salamander famous for regenerating limbs.

Conservation status

The five-lined skink is listed as Least Concern on the IUCN Red List of Threatened Species. That is the category as distributed by GBIF, the Global Biodiversity Information Facility, and we checked it on November 9, 2026. Least Concern means the species was evaluated and does not meet the criteria for a threatened or near-threatened category.

That does not mean every skink is safe. The Animal Diversity Web says the species’ distribution is patchy and colonial, so destroying habitat could cause local extinctions. The same page notes that skinks live up to about 6 years in the wild and that most die before reaching maturity, and it lists many animals that eat them. On the other hand, the Missouri Department of Conservation calls it one of that state’s most abundant lizards, and the Animal Diversity Web says many live in disturbed edge habitats. We have no confirmed population trend, because none of our sources states one.

Categories are reviewed and can change, and the copy GBIF distributes can trail the IUCN website by some months, which is why we print the date we checked. GBIF’s copy does not give the year of the assessment, so we do not state one.