A California kingsnake successfully consuming a ratsnake of 115% its own size. Credit: David Penning

Best constrictor on the lot, kingsnakes eat larger snakes for breakfast

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The kingsnake earns its name from its ability to capture, constrict, and kill other snakes larger than themselves, but new research has found that their dominance may be because they can apply much higher constriction pressures than other snakes. Their strength derives from a distinctive tight coil posture that allows them to generate significantly higher constriction pressures — three times that needed to stop blood flow in a rodent. Kingsnakes may not be the biggest, but this constrictive prowess lets these powerful predators trap other snakes in their grasp and swallow them whole.

Journal/conference: The Journal of Experimental Biology

Organisation/s: Missouri Southern State University, USA, University of Louisiana, USA

Funder: Partial funding was provided by the Louisiana Board of Regents (grants RD-A-34 and ENH-TR-77 to B.R.M. and Doctoral Fellowship to D.A.P.), the National Geographic Society (grant 7933-05 to B.R.M.), the National Science Foundation (IOS-0817647 to B.R.M.), the Department of Biology and the Graduate Student Organization at the University of Louisiana at Lafayette (to D.A.P.), the Louisiana Department of Wildlife and Fisheries Rockefeller State Wildlife Scholarship (to D.A.P.), the Kansas Herpetological Society (to D.A.P.), Miles of Exotics (to D.A.P.) and BhB Reptiles (to D.A.P.).

Media Release

From: The Company of Biologists


When a constricting snake and mammal find themselves at odds, you have a general idea of what to expect. However, when one snake feeds upon another snake, the outcome of their interaction is much less obvious. This area of mystery becomes even more intriguing when looking at kingsnakes (Lampropeltis). Kingsnakes have the amazing ability to capture, constrict, and kill other snakes that are also powerful constrictors and are larger than the kingsnake itself! How is it possible for one constricting snake to kill a larger constricting snake, using constriction?

David Penning an Assistant Professor at Missouri Southern State University, and Brad Moon an Associate Professor at The University of Louisiana at Lafayette set out to unravel the mystery of how a smaller snake can defeat a larger snake. Penning and Moon tested the constriction strength, escape performance, and muscle anatomy of kingsnakes and ratsnakes (another powerful constrictor that can be consumed by kingsnakes) in order to identify any mechanistic clues to this predator-prey interaction.

Through much of their experimentation they found no clues to a mechanism that allows one constricting snake to overpower another. The muscle anatomy was similar between species and their defensive performance was best predicted by their size but not species. However, a surprising result came from the constriction trials. A total of 182 snakes from six species had their constriction performance measured. To their surprise, all three kingsnake species constricted with significantly higher pressures compared to all three ratsnake species. The kingsnakes are so strong that some were able to produce constriction pressures over twice the values shown to induce circulatory arrest in rodents!

Penning and Moon report their findings in The Journal of Experimental Biology in their paper “The king of snakes: performance and morphology of intraguild predators (Lampropeltis) and their prey (Pantherophis)”. Their work shows that kingsnakes are successful predators on other snakes due in part to their ability to produce remarkably high constriction pressures compared to the snakes they can feed upon.

This work is the first to show that some snakes are stronger than others and kingsnakes can successfully prey on other snakes in part due to this high level of performance. The kingsnake’s success derives in part from their consistent use of a distinct coil posture that allows them to generate significantly higher constriction pressures compared to the snakes that they feed upon.


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