To find out, Penning and his colleague Brad Moon taped pressure gauges to pre-killed rodents, and then offered them to kingsnakes and ratsnakes—182 individuals from six different species. And they found a clear pattern: The kingsnakes exert about twice as much pressure as the ratsnakes. They look similar from the outside, but they somehow squeeze much harder. Why?

Penning and Moon ruled out two possibilities. They dissected several museum specimens and showed that kingsnakes are no more muscular

than ratsnakes. They measured how strongly the snakes can pull against a restraint, and found that neither group is better at escaping than the other.

They suspect that kingsnakes instead are stronger because they throw more efficient coils around their prey. “The peer reviewers preferred ‘spring-like’, but I call it the ‘curly-fry pattern,’” says Penning. “It’s an elegant, tight coil. Whereas the ratsnakes look like someone dropped spaghetti on something. They squeeze in a really haphazard way.” Perhaps that’s why they’re so bad at regicide.

Top: an eastern kingsnake; bottom: a corn snake, which is a species of ratsnake.

“I like that this study is driven by a novel idea, rather than by technology,” says Kate Jackson, from Whitman College. “The techniques used are relatively simple and the experiment could have been done long ago—only nobody had thought to take this approach until now.”

Penning next wants to check if the kingsnake’s coils really are more efficient, or whether there are subtler differences in their muscles. They may be the same size as a ratsnake’s, but could they generate more force? And what accounts for their phenomenal stamina? A typical fight can be over in a few minutes, but if the kingsnake is inexperienced, the wrestling can go on for six to seven hours. “Olympic wrestling bouts takes a few minutes,” says Penning. “This is like someone trying to do extreme weightlifting for hours.”

That same stamina also allows kingsnakes to easily overpower rattlesnakes, cottonmouths, and copperheads, which get exhausted after a few minutes of activity. Kingsnakes are immune to these vipers’ venom, so the vipers don’t strike—that would leave their heads exposed. Instead, they lift up their mid-sections and try to body-slam their attackers. That rarely works. Even these vipers, which we consider to be among the deadliest of snakes, cannot dethrone the kings.

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