Rare Dorsal Fin Regeneration Observed in a Silky Shark [Study]

Sharks are among the top predators in the ocean, and it's not a surprise since they have special abilities like rapid healing, continuous tooth renewal, and armor-like skin. A researcher also observed that a silky shark could regenerate its wounded dorsal fin.

Silky Shark (Carcharhinus falcifo) Regenerates Dorsal Fin

In a new study titled "Resilience in the Depths: First Example of Fin Regeneration in a Silky Shark (Carcharhinus falciformis) following Traumatic Injury," Chelsea Black, a shark scientist and conservationist detailed her encounter with a silky shark with an injured dorsal fin in 2022.

The discovery was made in the summer of 2022 while she conducted her research for her doctorate, which involved placing satellite tags- small GPS trackers- on ten silky sharks in Jupiter, Florida.

A local diver and photographer contacted her shortly after the tagging mission with photographs of a shark with a big wound on its dorsal fin. The wound appeared to have been meticulously sliced around, and the satellite tag was removed because it was precisely the shape of the tag. The plastic ID tag placed beneath the dorsal fin of every shark that has been satellite-tagged was also given to this particular shark, which stayed on it and enabled Black to identify it as one from the tagging project.

Since silky sharks are only seen in Florida during the summer, Black was surprised to see the shark again. Also, she couldn't track the shark anymore because the tag was removed so that she couldn't locate him.

She was shocked to see the same shark once more. Almost a year after being spotted with a damaged dorsal fin, the silky shark made his way back to Florida in the summer of 2023.

She saw the photos captured by Josh Schellenberg and John Moore and used specialist software to measure the dorsal fin's healing. She determined that the dorsal fin had grown by 10.7% the previous summer, indicating that new tissue had grown to compensate for the significant loss.

Dorsal Fin Regeneration in Sharks

Dorsal fin regeneration has only been found in a shark once before, in a whale shark in the Indian Ocean in 2006. As far as scientists know, sharks rarely exhibit the regenerative limb phenomena, whereas other marine species like starfish and crabs are well-known for this trait.

Even though there might be more instances of sharks growing new dorsal fins, it is very challenging to watch these situations because it is rare to witness a damaged shark more than once.

It is forbidden to keep or harvest silky sharks in Florida waters, which is probably why the shark was spared. Commercial and recreational fishermen frequently catch silky sharks in Florida waters, and the most current photos of the silky shark used in this study show many hooks in both sides of his jaw, suggesting he has been caught and released several times over a year.

It remains unclear why the satellite tag was removed, but based on how the tags are attached, Black concluded with certainty that human intervention is the only explanation for the shark's wound.

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