When a Toad Isn’t a Toad

What am I looking at?

These are two horny toad lizards (Phrynosoma platyrhinos), also known as desert horned lizards or horntoads. You can see the horns surrounding their heads (1) and the spiked scales lining their sides (2). Also notice that the pattern of colors on their backs and tails (3) mimics the coloration of the sand.

Click on the right arrow to see some alternate views of these lizards.

Biology in the background

These lizards are native to arid or semiarid areas of North America, such as the American Southwest. The horns that surround their heads are true horns in that they have a core of bone, while the spikes on their sides, tail, and legs are modified scales. They use these horns and spikes for defense, flattening their bodies and sticking out their spikes to make themselves look less appetizing and even dangerous for predators to eat.  

However, this is not their strangest defensive adaptation. Some species have also developed the ability to shoot blood from their modified tear glands to confuse predators while they make an escape. The blood is laced with foul-smelling chemicals that repel predators. Canines in particular – such as foxes and coyotes – find the odor off-putting.

They can harvest moisture from the environment using their skin, an adaptation to living in an arid habitat. Their scales form a network of capillary channels, which can wick water that condenses on their skin or that is present in moist sand and funnel it into their mouth. Their spiked scales also prevent water loss through their skin. In fact, their use of water is so efficient that they don’t have a urinary bladder to store excess liquid waste.

Their diet consists almost entirely of ants – specifically harvester ants.  

These lizards can grow up to 15 centimeters long (about 6 inches).

Technique

These images were created using macrophotography.