Despite being soft, squishy, and slow-moving, sea cucumbers (Class Holothuroidea) are surprisingly tough. They scavenge in harsh, rapidly changing conditions on the ocean floor, under the constant threat of toxic bacteria. To protect themselves against predators and pathogens alike, sea cucumbers produce defensive toxins called saponins, as do their close cousins, starfish. However, new research finds that sea cucumbers are the only echinoderms—and among the only animals on Earth—that produce chemicals called triterpenoid saponins, which don’t poison the sea cucumbers themselves thanks to their unique metabolic pathways.
A study published in Nature Chemical Biology finds that sea cucumbers have evolved a way to synthesize these saponins with different enzymes than those used by their echinoderm cousins and the vast majority of other animals. In doing so, they’ve evolved a mechanism that makes them immune to their own saponins.
“I think [the study] is really impressive,” Annalisa Pinsino, a marine biologist ...
