Organisms that are Totally Sweet! #1: Horned Lizards

Unique to North and Central America are the crazy-cool little horned lizards, otherwise known as “horny toads.” Horned lizards are NOT amphibians—they just happen to share a superficial resemblance with toads. They also remind me of miniature anklyosaurs, which were squat, spiky dinosaurs. The fifteen species of horned lizard are all members of the genus Phrynosoma, which, not surprisingly, means “toad-bodied” in Greek. Ants are the primary food source for horned lizards. A horned lizard’s scaly skin protects it from stinging ants while it laps the insects up with a sticky tongue.

Horned lizards are slow runners compared to many of their iguanid relatives, and must therefore rely on an assortment of other defense mechanisms when dealing with would-be predators. Camouflage is one of the best defenses horned lizards have. Their variegated skin patterns blend in amazingly well with the sand and gravel of their habitats. I have been startled on several occasions when a horned lizard scurried away just before I almost stepped on it (unwittingly, of course). As soon as they stop moving, horned lizards are very hard to see. Most Phrynosoma species have sharp horns jutting from their heads. Remember that time you swallowed a tortilla chip without chewing it up properly? It scraped the inside of your esophagus and hurt like hell, right? Coyotes and foxes don’t eat tortilla chips, normally, but they might avoid eating horned lizards after a painful experience trying to choke down those horns. Horned lizards have another defense that makes them difficult to swallow: they get all puffed up by gulping air.

Last but not least in the horny toad bag-o-tricks is the ability of some species to squirt blood from their eyes! This above all else is why horned lizards are totally sweet. When I was a kid, I thought this was pure mythology, but it’s true! If sufficiently pissed off, some horned lizards can shoot a jet of blood several feet from sinuses in the corners of their eyes. Wade Sherbrooke—a biologist who literally wrote the book on North American horned lizards—has found that there is a noxious substance mixed with the ejected blood that is distasteful to canids (dogs, coyotes, foxes, etc.). This blood-squirting behavior is more easily elicited by canids—the natural predators of horned lizards—than humans. Maybe that’s why I thought it was a myth: there probably weren’t that many documented cases of horned lizards squirting blood back in the day, when I was a lad.

Here’s a video. Sorry about the commercial you will be forced to watch first.

Blood Squirting From Regal Horned Lizard Eye Watch Video Clip

Another fascinating trick of these lizards is the ability to “harvest” rain by channeling water along the fine crevices of their skin towards their mouths. This is a valuable adaptation in the desert environments that many horned lizards call home. Rain drops hit the lizard’s broad, flat body, and the water moves to the mouth via capillary action. The thorny devil lizards of Australia—also desert dwellers—collect water in a similar way, making this an example of convergent evolution.

Lastly, I want to share these amazing and salacious photos of horned lizards (Phrynosoma douglassi) mating (you must be over 18 to view them). I came across these in an interesting note by Craig Guyer published in Herpetolgical Review (Volume 37, issue 1, 2006). Craig was kind enough to give us permission to use the photos here at Salamander Candy. I have heard that “face-to-face” mating is rare in the animal world. Among the few examples I am aware of are dolphins and other cetaceans, humans, and now horned lizards. Note: the bigger of the two mating lizards is the female.

Okay, okay… I have to say it:
MAYBE THAT’S WHY WE CALL ‘EM HORNY TOADS!
Get it? Big laughs all around…