Japanese Five-lined Skink

Fascinating facts about the Japanese Five-lined Skink

• First described in 1861 by Edward Hallowell, this skink was once shuffled into the genus Eumeces before being placed in Plestiodon latiscutatus.
• At full grown it measures 15–24 cm from tip of tail to nose, but the body itself is only 6–9 cm long, about the length of a standard pencil. That compact size lets it slip through leaf litter and hide in rock crevices that larger lizards would miss.
• In the spring, from mid-April to late May, females lay four to twelve eggs and roll the clutch in the nest. Removing the mother causes the eggs to fail, highlighting how parental care is essential for this species' survival.
• Its diet includes earthworms, spiders, ants and tiny crustaceans such as Amphipoda.
• While the IUCN rates the species as Least Concern, isolated islands like Miyake-jima, Hachijō-jima and Aogashima show declining numbers after Japanese weasels were introduced to chase rats. Those local drops remind us that a single predator can tip the scales for island-bound wildlife.

At a glance

About the Japanese Five-lined Skink

The Japanese Five-lined Skink, Plestiodon latiscutatus, is a sleek, green-tinged lizard that measures 15–24 cm from snout to tail tip, with a snout-to-vent length of 6–9 cm. Juveniles are instantly recognizable by their vivid blue, slightly greener tail, a flash of color that fades as they mature, while the adult’s five faint, longitudinal stripes become less pronounced than those of its close relatives, P. japonicus and P. finitimus. Its scales are arranged in more rows on the outer Izu islands, a subtle morphological cue that helps herpetologists differentiate it from the similar species that share its range. The skink’s habitat spans the Izu Islands and the Izu Peninsula, where it occupies forest floors and leaf litter, hunting a diet of earthworms, spiders, ants, amphipods and other invertebrates. Mating erupts each spring, from mid-April to late May, and females lay clutches of four to twelve eggs every two years, carefully rolling the eggs in the nest until hatching, a behavior that proves vital, as experimental removal of the mother leads to near-total egg failure. A surprising trait of this species is its adaptive clutch size: islands with lower skink densities produce larger clutches, suggesting a flexible reproductive strategy tuned to local population pressures. Beyond the forest floor, the skink’s range brushes against the borders of its congeners. To the southwest, P. japonicus occupies southwestern Honshū, Shikoku and Kyushu, while P. finitimus extends northward into Honshū and Hokkaido. The biogeographic divide runs along the lower Fuji River on the northwest side of the Izu Peninsula and follows the Sakawa River on the northeast, echoing ancient marine separations that once split the peninsula from the rest of Honshū. Within this narrow overlap, the three Plestiodon species display distinct mitochondrial DNA signatures, underscoring a deep evolutionary history that continues to shape their present-day interactions.

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