'One in a Million' Dolphins With Hook-Like Flippers

Striped dolphins have two strange flippers, most likely due to a genetic abnormality that occurs during development in the womb.

Striped dolphins with strangely shaped flippers. Photo: Alexandros Frantzis/Pelagos Cetacean Research Institute

Scientists from the Pelagos Cetacean Research Institute discovered a unique striped dolphin ( Stenella coeruleoalba ) off the coast of Greece, IFL Science reported on December 18. The flippers on both sides of the animal were hooked, creating a shape resembling a hand with a thumb. However, the team found that the striped dolphin still performed normal behaviors with its pod in the Gulf of Corinth in the Ionian Sea.

Striped dolphins are relatively common, with males typically reaching 9 feet (2.7 m) in length and weighing around 350 pounds (158 kg), while females reach 8 feet (2.4 m) in length and 330 pounds (150 kg). They are highly social and travel in large pods of up to 100 members. They are active, agile and flexible, and can jump up to 20 feet (6 m) above the water, according to the National Oceanic and Atmospheric Administration (NOAA).

"This is the first time we have seen this surprising flipper morphology in 30 years of marine surveys as well as in studies of stranded dolphins along the Greek coast," said Alexandros Frantzis, president of the Pelagos Whale Research Institute.

The unusual flipper shape is likely due to a genetic glitch in the dolphin’s development in the womb. Anatomically, humans and dolphins are very similar in their wrists and hands.

"Their fingers are connected in a unique order, with very strong connective tissue. In this case, one finger is not fused to the others but remains separate. This can happen in the first or second month of pregnancy. It is difficult to say specifically without X-rays. Something unusual has happened during development, a case that is only one in a million," explains Professor Bruno Cozzi, author of the book Anatomy of Dolphins .

Cozzi believes that the striped dolphin's odd flippers are genetically determined, not due to injury, as the condition affects both flippers, rather than just one. He also believes that the dolphins will not suffer many negative consequences from the change in flipper shape. "Dolphins don't use their flippers for grasping, so it won't have much of an impact. Maybe their swimming ability will be a little impaired," he said.

Thu Thao (According to IFL Science )

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