An Eye in Your Tail
Can you imagine having an eye somewhere else in your body– and using it to see? Researchers claim to have made a tadpole do just that. They used a tadpole of the frog Xenopus laevis, a common model system for vertebrate development. They used blind frogs, and inserted a bit of embryonic eye tissue in the tail. The tissue developed into an “ectopic eye” (see eye in the tail above, at right).
In some tadpoles, the eye developed nerves that reached the spinal cord. Other eyes did not. But the tadpoles with the spinal-connected eyes could distinguish red light from blue light, in a stimulus-reward test. That implies that the tadpoles could “see” with their tails, even though the ectopic eyes do not directly connect to the brain, the way eyes normally do.
Think of the possibilities this suggests for science fiction.