Specifically, the stinging cells of “sea anemones, hydrae, corals and jellyfish”:
In new research published in the Proceedings of the National Academy of Sciences on May 2, Leslie Babonis, assistant professor of ecology and evolutionary biology in the College of Arts and Sciences, showed that these stinging cells evolved by repurposing a neuron inherited from a pre-cnidarian ancestor.
“These surprising results demonstrate how new genes acquire new functions to drive the evolution of biodiversity,” Babonis said. “They suggest that co-option of ancestral cell types was an important source for new cell functions during the early evolution of animals.”
Cornell University, “Jellyfish’s stinging cells hold clues to biodiversity” at ScienceDaily (May 12, 2022)
So they “repurposed” cells from an earlier ancestor to produce these cnidocytes?
“One of the unique features of cnidocytes is that they all have an explosive organelle (a little pocket inside the cell) that contains the harpoon that shoots out to sting you,” Babonis said. “These harpoons are made of a protein that is also found only in cnidarians, so cnidocytes seem to be one of the clearest examples of how the origin of a new gene (that encodes a unique protein) could drive the evolution of a new cell type.”
Cornell University, “Jellyfish’s stinging cells hold clues to biodiversity” at ScienceDaily (May 12, 2022)
It’s hard to avoid the sense of design here.
The paper is open access.