Awesome photos! Thanks for sharing that CTYankee9. I didn't know that they did that. Very cool!
Very nice photos, CTY.
Horned lizards have a number of defenses, including the blood squirting behavior you observed. I've seen it once - when Groovy, about 9 or 10 at the time, brought one home from a nearby canyon for a few hours. It was startled by his pet rat and whoosh, out came the blood.
Here are a few of many articles that describe the phenomenon. The video clip at the National Geographic site is fun to watch - unless you are a coyote.
San Diego Natural History Museum article
Wikipedia article
National Geographic video clip
Yeah, had to check when I got home on what it was, was a bit worried that the Piglit had done something to it {damaged}, but it seems was just a natural defensive action! Oh yeah, I didn't actually see it jet like in the video and there wasn't any blood on Piglit, but that would have been cool to capture on the camera.