Bdelloid rotifers are resistant to ionizing radiation due to enhanced capacity for scavenging destructive radiation-induced molecules before they have a chance to cause damage.

Ionizing radiation, including that from nuclear materials and X-rays, can damage DNA and proteins directly by forming or breaking bonds in DNA or indirectly by the formation of reactive oxygen species (ROS). ROS, such as free radicals and peroxides, can destroy proteins. D. [Deinoccocus] radiodurans and bdelloid rotifers are able to survive exposure to ionizing radiation because they are able to scavenge ROS before they can wreak havoc, thereby leaving proteins charged with repairing damaged DNA to do their job.

References

"Rotifers of class Bdelloidea are common invertebrate animals inhabiting temporary freshwater pools, the surfaces of mosses and lichens, and other ephemerally aquatic habitats. Their success in such habitats depends on their extraordinary ability to survive desiccation at any stage of their life cycle...We propose that the extraordinary resistance of bdelloid rotifers to IR [ionizing radiation], like that of the bacterium Deinococcus radiodurans, is a consequence of evolutionary adaptation to survive desiccation in ephemerally aquatic habitats and that such desiccation causes extensive DNA breakage, which they are able to repair." (Gladyshev et al. 2008: 5139)

"The association of resistance to IR with anhydrobiosis and the observation that desiccation, like exposure to IR, is accompanied by the production of reactive oxygen species (41) and protein oxidation in diverse biological systems and that proteins of desiccation-resistant bacteria are protected against such damage (33, 42) indicates that at least part of the damage caused by desiccation is the same as that caused by radiation…The picture that emerges from the above considerations is that a major defense against radiation damage in D. radiodurans and bdelloid rotifers, accounting for the distinctive shoulders in their dose–response relations, is an enhanced capacity for scavenging the reactive molecular species generated by IR and that the proteins and other cellular components thereby protected include those essential for the repair of broken DNA." (Gladyshev et al. 2008: 5142)

Journal article
Extreme resistance of bdelloid rotifers to ionizing radiationProceedings of the National Academy of SciencesMay 29, 2017
E. Gladyshev, M. Meselson

Journal article
A new perspective on radiation resistance based on Deinococcus radioduransNature Reviews MicrobiologyMay 29, 2017
Michael J. Daly

Living System/s

Organism
Predatory MitesBdelloideaFamily