Blanus cinereus Vandelli, 1797

Common Name & Body Form

Blanus cinereus, commonly called the Iberian worm lizard, has a worm-like limbless ringed body, but differs from true worms in several features: it has small underdeveloped eyes, small smooth scales, and all the core traits of a typical vertebrate including a vertebral column, lungs, and a closed circulatory system.

Head and Body Adaptations

Its small blunt head is adapted for digging, with underdeveloped eyes covered by skin, and its characteristic ridged ringed body is covered in scales.

Tail Characteristics

Iberian worm lizards have short tails that are covered in the same scales as the rest of the body.

Oral and Sensory Features

They have a small forked tongue used for chemosensory signaling, and a row of small, sharp teeth inside the mouth.

Body Coloration

Their body color is fleshy-pink, violet, or brown, varying by region.

Adult Size

Adults are usually around 150 mm (5.9 in) in total length, and can grow up to 300 mm (12 in) long.

Common Misidentifications

They are often mistaken for small snakes or large worms.

Geographic Range

The Iberian worm lizard is found in Portugal and across most of central and southern Spain.

Habitat Type

Blanus cinereus is a subterranean species that occurs in a wide range of Mediterranean habitats.

Population Estimation Challenges

Because it lives underground, it is difficult to estimate its population abundance across different regions.

Elevation Range

Activity studies confirm that the species can survive in habitats located between 400 meters and 1400 meters in elevation.

Thermoregulatory Requirements

It is a thermoregulator, so it can only survive in habitats that meet its thermoregulatory requirements.

Habitat Soil and Rock Features

Typical habitats for this species have high humus content and scattered rocks of varying thickness.

Temperature Regulation Behavior

The Iberian worm lizard uses its habitat’s loose soil depth and rocks to help regulate its body temperature.

Daily Burrowing Depth

Depending on the time of day, it moves between 0 cm and 10 cm deep in soil and takes shelter underneath rocks that range from 10 cm to 20 cm thick.

Temperature Adjustment Mechanisms

It uses deeper soil to cool down, and rocks to warm up, adjusting based on time of day and rock thickness.

Thermoregulation Energy Cost

By using habitat features this way, it can maintain a constant body temperature with very low energy cost.

Environmental Chemosensory Signaling

There is evidence of chemosensory signaling between the Iberian worm lizard and its environment.

Burrowing Escape Response

This can be observed in how quickly the species burrows into soil to escape predators in familiar versus unfamiliar locations. When predator cues are detected in an unfamiliar location, Blanus cinereus is slower to start burrowing; when returned to its familiar habitat, its burrowing escape response becomes much faster.

Precloacal Secretion Content

Precloacal secretions from both male and female Iberian worm lizards contain long-chain waxy carboxylic acid esters.

Secretion Function

It is thought these secretions are left along the species’ tunnels to help other Iberian worm lizards navigate.