Footage Captures Extremely Rare Dolphin with ‘Thumbs’

Photographs and video of dolphins in the a gulf off of Greece show the aquatic mammals swimming, a majestic sight on its own. But one dolphin was particularly intriguing for its rare pair of “thumbs.”

The underwater images, captured by Alexandros Frantzis, Pelagos Cetacean Research Institute President and Scientific Coordinator, in the Gulf of Corinth off of Greece show a number of dolphins during surveys conducted by the organization. Frantzis recently spoke with science news site Live Science about the amazing image, shedding light on how this quirk of nature came to be and just how rare it really is.

“It was the very first time we saw this surprising flipper morphology in 30 years of surveys in the open sea and also in studies while monitoring all the stranded dolphins along the coasts of Greece for 30 years,” Frantzis told Live Science.

He added that the “thumbs,” as they appear, do not seem to be related to any illness but rather they are more likely “the expression of some rare and ‘irregular’ genes” caused by persistent interbreeding.” The YouTube video, posted by the Pelagos Cetacean Research Institute notes that a thumb appears on both of the dolphin’s pectoral fins, the ones located to on the animal’s sides.

Lisa Noelle Cooper, an associate professor of mammalian anatomy and neurobiology at the Northeast Ohio Medical University, also shared insights with Live Science.

“I’ve never seen a flipper of a cetacean that had this shape. Given that the defect is in both the left and right flippers, it is probably the result of an altered genetic program that sculpts the flipper during development as a calf,” Cooper told the publication, echoing Frantzis’ thoughts.

She explained that dolphins have finger bones but that cells accumulate around them, forming flippers. Cooper told Live Science, “Normally, dolphins develop their fingers within the flipper and no cells between the fingers die off.”

Regardless, the dolphin was seen by the Pelagos Cetacean Research Institute on two occasions, each time “swimming, leaping, bow-riding, playing” with the other dolphins, Frantzis told Live Science. Hopefully, more footage of the uniquly thumbed dolphin will surface.

Image credits: Photographs by Alexandros Frantzis / Pelagos Cetacean Research Institute