Dolphin With ‘Thumbs’ That Look Like Bottle Openers Off Greece

Dolphins are brilliant. They are widely believed to be the second smartest animals on Earth behind humans and are capable of abstract thought and complex problem solving. And, apparently, some may be evolving to have thumbs… The above image of a dolphin giving a thumbs up was made using Meta’s Imagine AI, for what it’s worth, and only meant as a joke. The real dolphin with ‘thumbs’ can be seen below.

Let me specify what we’re talking about here because this topic can get a little messy. A dolphin with ‘thumbs’, a first-of-its-kind defect, was photographed off Greece in the Gulf of Corinth. That dolphin’s ‘thumbs’ look a bit like bottle openers. But, all dolphins theoretically have ‘thumbs’ inside their flippers, thumbs that are part of their skeletal system. What makes this anomalous dolphin so special is how those thumbs are expressed.

As you can see here, the dolphin’s fin is not fully developed and it has curved ‘thumbs’ which look a bit like bottle openers. At first glance, one might assume it was due to an attack of some sort but the defect is identical on both sides.

Lisa Noelle Cooper is an associate professor of mammalian anatomy and neurobiology at the Northeast Ohio Medical University and told Sascha Pare of Live Science she believes these ‘thumbs’ are the result of a genetic defect.

Cooper said “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.”

Image made using Meta’s Imagine AI

To understand how that would happen, we have to get a little science-y for a moment. But first, here is what the finger bones (phalanges) of a dolphin looks like and note how similar it is in shape and build to that of a human being, just a little extra:

So, as you can plainly see, dolphins have thumbs. How we humans grow our hands and how dolphins (cetaceans) grow their hands/flippers differ greatly, however. Humans grow our hands in the womb using cells that are gone before we leave the womb. Dolphins, unlike humans, grow their ‘fingers’ inside of the flippers and Professor Cooper tells LiveScience the cells between those dolphin flippers don’t die off (unlike in humans where they do).

The hypothesis then, on how this first-of-its-kind dolphin with thumbs came to exist, is those cells that would grow some of the dolphin’s fingers did die off.

Cooper says “It looks to me like the cells that normally would have formed the equivalent of our index and middle fingers died off in a strange event when the flipper was forming while the calf was still in the womb.” It is a hypothesis so not necessarily the end-all-be-all answer but it’s a pretty good hypothesis so far.