Skeleton of a Chameleon

What am I looking at?

This is the embryo of a veiled chameleon (Chamaeleo calyptratus) that’s been stained to visualize its developing skeleton. Its bones are red (1), the cartilage is blue (2), and some of its developing internal organs and its eyes are yellow (3).

Biology in the background

Most chameleons live in trees, and the bones of these lizards’ feet and tails have adapted to that environment. You can see that this chameleon’s tail is long and curled, making it prehensile – perfect for wrapping around branches and providing balance and support while it climbs through the trees. You can also see that each of the chameleon’s feet has five toes arranged in a V shape, with two on one side of the V and three on the other side; this arrangement, called zygodactyly, is good for grasping branches.

You may also notice that the eye sockets in its skull are much larger than the eyes themselves. Chameleons’ eyes are attached to the socket via a circular arrangement of muscles that allows them to move their eyes in almost any direction. They can also move their eyes independently of each other, giving them the potential to have an almost 360-degree view of their surroundings at any given time.

The blue rod visible inside the lizard’s throat is attached to the chameleon’s famously long tongue. A muscle called the lingual accelerator muscle surrounds the rod, and its contraction stores the energy necessary for the tongue’s impressive launch and speed.

This species’s prehensile tail, zygodactylous feet, and ballistic tongue are all adaptations for a life spent in the trees, eating insects.

An adult veiled chameleon can grow up to 61 centimeters long, or roughly two feet.

Technique

This image was created using high dynamic range imaging, a form of macrophotography.