Anyone who has been stung by a jellyfish might think they know more than enough about cnidocytes, the cells that deliver the sting. But Leslie Babonis has found that these cells have much more to tell, including insight into a simple evolutionary mechanism that may enable jellyfish, sea anemones, corals, and their relatives—collectively known as cnidarians—to quickly adapt to new environments. Babonis has found that a single genetic switch can transform cells that sting into cells that cling, enabling the animal to colonize new surfaces. The work suggests this kind of switch may have helped power evolutionary transformations for hundreds of millions of years.

The finding, reported last week at the virtual annual meeting of the Society for Integrative and Comparative Biology, is “an impressive biological discovery … [providing] powerful observations about how new cell types evolve and arrive in novel places” says Kristen Koenig, an evolutionary developmental (evodevo) biologist at Harvard University. Researchers have long known that some single genetic switches can cause one body part to develop as another in more complex organisms. But Babonis’s finding suggests this simple mechanism for evolutionary change dates back to some of the earliest animals.

Cnidocytes have multiple guises, making them a tempting focus for biologists studying how new kinds of tissues evolved. The stinger cells (also called nematocytes) of jellyfish shoot tiny, toxin-laden harpoons, whereas some cnidocytes in sea anemones and corals shoot out threads of sticky material that help the animals anchor themselves in substrates like mud. “The cnidocytes are a great model system to study the evolution and diversification of novel cell types,” revealing principles that can be applied to other animals, says Billie Swalla, an evodevo researcher at the University of Washington, Seattle.

Read the full article in Science.