Move over, Karate Kid. The kangaroo rat is a tiny little rodent, adorable by most standards, harmless except to vegetables, and utterly defenseless – one would think. One would be wrong. They move like ninjas, scientists found after filming encounters between kangaroo rats and lightning-fast rattlesnakes, writes the student-led team from UC Riverside, San Diego State University.
The discovery debunked the theory, born of bafflement, as to why kangaroo rats seemingly survive snake strikes. They do not. They avoid them. And no, they are not immune to snake venom. If the snake gets its fang in, the rat's story is over.
Kangaroo rats avid getting eaten by lightning-fast reptiles through a combination of fast reaction times, say the students, Olympian evasive leaps, rolling madly, and mid-air, ninja-style kicks. They don't cavil at kicking each other, by the way. Don't take our word for it – watch this.
In fact the team published not one but two papers on its version of Alien vs Predator – Kangaroo Rat Versus Rattlesnake, in the wild no less: one in Functional Ecology and the other in the Biological Journal of the Linnean Society ("Escape dynamics of free-ranging desert kangaroo rats (Rodentia: Heteromyidae) evading rattlesnake strikes." The papers analyze the behavior and biomechanics of both kangaroo rats and the vipers. Rattlesnakes are vipers, to be clear.
And how exactly did the team get so much delicious footage (if not for the poor snake)?
They used radio telemetry "to patiently track the hunting behavior of free-ranging rattlesnakes," they write. Then they located places frequented by kangaroo rat. Then they located high-speed cameras there. Ta da!
A moment of statistics: You blink for about 150 milliseconds. Now you know that. For a rattlesnake to launch from stillness to strike, resulting in kangaroo rat for dinner, takes 100 milliseconds – unless the diminutive rodent was prepared. The students found a typical rat reaction time of 70 milliseconds, but the speedy among the rodent crowd could initiate jumps within 38 milliseconds of a snake starting its strike – leaving the snake with a mouthful of dust.
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"Our work, which, to our knowledge, is the first to describe the kinematics of evasive leaps by bipedal rodents avoiding actual attacks from predators, supports the idea that bipedalism may have been favored in kangaroo rats because it allows for the rapid and powerful leaps needed to avoid ambush predators such as vipers and owls," suggested Grace Freymiller of San Diego State University, the student lead author of the second paper. Makes sense.