Joshua Tree (Yucca brevifolia)
Last weekend I went out to Joshua Tree National Park for a class on snakes and venom. We did see a speckled rattlesnake in the hills above one of the campgrounds, and the instructor brought some snakes as well.
Speckled Rattlesnake. His eyes are milky looking because he is getting ready to shed his skin. The heads of vipers like rattlesnakes are triangular in shape to accommodate their venom glands. This is one way to tell if the snake you are looking at is a rattlesnake or not.
Of course the other way is to look at the tail...
This is a sidewinder rattlesnake. Notice the little "horns" above the eyes. These probably serve to shade the eyes from the sun and may offer protection as the animal moves through sand as well. Vipers like the rattlesnakes bite their prey, then usually let it go. They can track the movement of their prey, and then can catch up to it once it is dead and safe to eat. Vipers have pits that allow them to sense heat from their prey, and visualize prey based on the heat given off from the body. You can see the pits on the head of this snake below the eye.
After the class I went into the park to photograph the landscape. Lucky for me the moon was up and just about full.