In July 2023, researchers from the Pelagos Whale Research Center found a distinctive striped dolphin with deformed tufts that resembled thumbs. The dolphin was seen swimming with his group and this appearance defect did not seem to bother him.
Experts believe that the deformity is likely to be a genetic defect, as both of the bundles look like this. Although cetaceans, including striped dolphins, have finger bones embedded in their gills, suggesting the evolution of whales from terrestrial mammals, some of those bones appear to be missing from this particular dolphin. Despite this variation, the dolphin appears to be in good health.
Read more here:
https://www.livescience.com/animals/dolphins/extremely-rare-dolphin-with-thumbs-photographed-in-greek-gulf
