The hypodermic needle-like fangs swing down as the snake lunges forward to strike. Fangs are not permanent, but are periodically replaced. The ability to dispense venom means life or death for the rattlesnake. The triangular head gives way to a narrow neck, thick body, and a tail tipped with a series of inter-locking segments making up the rattle. Every time a snake sheds its skin a new segment is added.
Snakes shed from one to three times a year.
Rattlesnakes do not always rattle in warning and a rattle does not always precede a strike. Rattlesnakes do not hatch from eggs, they are born alive from mid-summer to fall. The ability to vibrate the tail is instinctual, but the rattle cannot be heard until juveniles shed at least three times. Juvenile rattlesnakes can deliver a fully potent bite. Primarily inhabiting valleys and bajadas, a series of backward J or S shapes left in loose sand indicates one has passed by.