Sensitivity to anesthesia by pregnanolone appears late in evolution.

@article{Oliver1991SensitivityTA,
  title={Sensitivity to anesthesia by pregnanolone appears late in evolution.},
  author={Ann E. Oliver and David Deamer and M A Akeson},
  journal={Annals of the New York Academy of Sciences},
  year={1991},
  volume={625},
  pages={561-5}
}
The anesthetic effect of certain steroids in vertebrate systems is well documented, but it is not known if these compounds can cause anesthesia in simpler organisms. To answer this question, ether, short-chain alkanols, and pregnanolone were tested for their ability to induce anesthesia in 20 aquatic species from 7 phyla. Organisms were placed in water… CONTINUE READING