When you think of a dolphin, you're probably picturing the happy animals we're all used to seeing on TV, in films and out at sea.
You'll be thinking of the smiling, shiny, bottle nosed dolphin that we're all used to seeing when we think of the animal. The smooth and sleek lines of the dolphin don't usually come with thumbs, or a 'hook like' feature - or at least they're not supposed to.
Yet off the coast of Greece, a dolphin has been spotted that has strange, hooked thumbs on its flippers.
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Spotted along the Gulf of Corinth, the unusual looking dolphin was spotted in a mix of various species of dolphins, including common dolphins (Delphinus delphis), Risso's dolphins (Grampus griseus) and striped dolphins (Stenella coeruleoalba).
The Pelagos Cetacean Research Institute was the first to spot the unusual-looking mammal, which was spotted twice while the group conducted its boat surveys and studied the species.
Alexandros Frantzis, president of the research institute, spoke out as he highlighted that despite the dolphin having the unusual feature, it didn't stop it from keeping up with others in the group.
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Speaking to Live Science, he explained: "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 also told the website that the deformed flipper is most likely "the expression of some rare and 'irregular' genes."
Lisa Noelle Cooper, a mammalian specialist, also believes the 'thumb' feature could be due to the dolphin's genes. Also speaking with Live Science, she told the outlet: "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."
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She added that humans develop their fingers into hands in the womb, with cells dying off before birth. However, for dolphins, cells build up around their forelimbs to form the flippers that we're used to seeing on these mammals.
She stated: "Normally, dolphins develop their fingers within the flipper and no cells between the fingers die off."
However, the anomalous dolphin appears to have developed differently.
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"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," Cooper theorised.
While the sighting of a thumb in the wild might lead us to wonder if dolphins are developing and could eventually evolve to have hands like humans, it is unlikely.
Cooper explained: "The hook-shaped 'thumb' may have some bone inside of it, but it certainly isn't mobile." She then pointed out that "no cetaceans have mobile thumbs."
Whether it has a thumb or not, it's clear the dolphin isn't letting it stop it from living it's best life with its dolphin pals, as Cooper added: "It is lovely to see that this animal is thriving."
Niamh Spence