The African crested rat is not exactly the continent’s most fearsome-looking creature. The rabbit-sized rodent resembles a gray puffball crossed with a skunk—yet its fur is packed with a poison so lethal it can fell an elephant, and just a few milli-grams can kill a human.
The crested rat is the only mammal known to sequester plant toxins for chemical defense. And the rodents have an unexpected social life—they appear to be monogamous and may form small family units with their offspring, according to a new study by U researchers and scientists from the Smithsonian Institution and the National Museums of Kenya.
“It’s considered a ‘black box’ of a rodent,” says Sara Weinstein, lead author and Smithsonian-Mpala postdoctoral fellow and postdoctoral researcher in the School of Biological Sciences at the U. “We initially wanted to confirm that the toxin sequestration behavior was real and along the way discovered some completely unknown things about their social behavior.”
When threatened, the crested rat erects a ridge of hair on its back to reveal a warning on its flanks—black and white stripes running from neck to tail on each side of its body. A 2011 study hypothesized that the rats chew bark from the Acokanthera tree and lick the plant toxins into specialized hairs at the center of these stripes.
In the new study, researchers trapped 25 crested rats, the largest sample size of the species ever captured. They recorded nearly 1,000 hours of rat behavior with motion-activated cameras. For the first time, they documented multiple rats sequestering Acokanthera toxins and discovered many traits that suggest that they are social, and likely monogamous.
The research team is planning future studies to learn more about the rats’ physiology and behavior, as well as the genetic mechanisms that allow them to withstand the toxins.