A walk on the wild side..

Costa Rica is home to three species of basilisks, lizards that run on water.  Because they can run on water, members of the genus Basiliscus are often called ‘Jesus Christ Lizards’.

Scientists carefully examined video-taped sequences of the Common Basilisk (Basiliscus basiliscus) running across water, and   built mechanical models in order to figure out how these large lizards cross water without sinking.

The scientists found that basilisks only run on their hindlegs, when darting across water.  When they run, a narrow seam of skin around each of their toes forms moveable flaps that  expand when their foot is pressed down on the water.  This creates a larger surface area for them to run on.

When the lizard puts its foot down the water, an air-filled pocket is formed around the foot that quickly fills with water again.   Before the water fills the air space,  the lizard needs to pick up its foot so that it doesn't have  to ‘plow’ through the water.

When it picks up its foot, the moveable skin-flaps on the toes fold down against the sides of the toes to reduce friction against the air. This means that the lizard can move its foot through the air very quickly. 

The combination of speed and specially adapted toe fringes allows these lizards to perform their impressive trick of running on water.

There are not many candidates that might potentially be able to walk on the water since most lack the ideal combination of a foot with a large surface area, combined with a relatively low body weight found in basilisks. 

Apart from a few birds, no other animals have been able to copy this form of escape behavior.

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