From a coiled position, an Eastern Diamondback Rattlesnake usually strikes 1/3 to 1/2 of its body length. The snake can strike farther.
Strikes are usually completed in less than .5 seconds.(Kardong and Bels)
The head accellerates to around 3.71 meters/second at a rate of 330 meters/second/second (Travis J. LaDuc, personal comm.); experiencing about 3.6 g's (about the same g-force as the space shuttle taking off, a top fuel dragster, and 4 times the acceleration of a 1997 Dodge Viper).
The initial head movement towards the target takes around 80~100 milliseconds (Travis J. LaDuc)
The forces are then transferred to the posterior of the body to decelerate the head. This is to minimize the impact of the head with the target. The head is launched forward with the mouth open to an 88-90 degree angle. The bottom jaw usually makes contact with the target, then the curved fangs are driven in via a clamping action of the top jaw. (Kardong and Bels)
Compressor muscles around the venom gland then apply pressure to the gland. The strike is aimed using a combination of thermal triangulation with the heat sensing pits smell, and to a lesser degree... sight. Snakes tend to strike more often at warm, moving objects.
Ken Kardong found that when blindfolding either the eyes or the pits, the accuracy of the strike was not affected. (They are just as accurate in total darkness)
A comparison of two defensive coil positions used by rattlesnakes
A few days ago, while looking at the back cover of my own book, I noticed something...
I've attached two photos. One showing an Eastern Diamondback Rattlesnake in what I will call a "Strong Base Coil" and a Timber/Canebrake Rattlesnake in what I will call a "Long Reach Coil"
The Strong Base Coil uses the rear third of the body to anchor the snake with a low center of gravity and a strong base from which to strike. The first third of the body, including the head, is held in a typical "S" curve. Only the first third to half of the body is extended in a strike with the latter half of the body anchoring the snake. If the snake were to try to straighten its entire body there would be one spot where the body loops around.
The Long Reach Coil places the entire length of a snake into a zig-zag back to the tail. It is possible for the snake to use only the end of its tail as an anchor point and straighten the entire length of the body in a strike.
I think that in both coils, the momentum of the strike could bring the rest of the body forward a bit. The strike from the Long Reach Coil is most likely not as accurate as one launched from the Strong Base Coil, but has a potential for a much longer reach.
I'm definitely not an expert in biomechanics, but I did feel that this was worth noting and recording. I've been watching my captive snakes, and the Strong Base Coil seems to be much more prevalent. I'm definitely going to keep an eye out in future encounters with snakes. I'd love to hear your opinion. Email me at firstname.lastname@example.org