Introduction
For the first time ever, scientists have documented a shark regrowing a fully torn dorsal fin. The discovery was made by marine biologists in Australia who had been monitoring a silky shark in the Great Barrier Reef for over a year after its dorsal fin was completely severed by a boat propeller.
The remarkable regeneration, captured on camera, upends previous beliefs that sharks could not regrow severed fins. It also demonstrates their resilience and adaptability, which has enabled them to survive for hundreds of millions of years.
Discovery of the Injured Shark
The shark was first spotted in October 2021 by a dive team from Citizens of the Great Barrier Reef during a reef health survey. The 1.5 meter female had a very distinct injury – her entire dorsal fin was missing.
The silky shark when first discovered with its dorsal fin fully severed. (Image credit: Citizens of the Great Barrier Reef)
The silky shark had a clean cut just anterior to where the dorsal fin attaches, indicating the fin was not bitten off by a predator but likely severed by a boat propeller. The dive team decided to monitor the shark’s recovery and took photos for identification.
Over the next year during subsequent surveys, the team sporadically caught glimpses of the same shark. But it wasn’t until December 2022 that they witnessed something unprecedented.
Recorded Footage Reveals Regenerated Fin
When the dive team spotted the distinctive shark on December 16, 2022, they immediately noticed something remarkable. The female shark’s dorsal fin had mostly regenerated, a feat never before documented in sharks.
Underwater photographer Monty Hall captured clear footage showing nearly the shark’s entire dorsal fin intact again, aside from a small notch at the rear tip. The regenerated fin displays the species’ characteristic long, curving front section and triangular rear portion.
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The silky shark re-sighted nearly 14 months later with most of its dorsal fin regenerated. Only a small notch is missing from the rear tip. (Image credit: Citizen of the Great Barrier Reef)
Significance for Shark Research
This serendipitous documentation has enormous implications. Marine biologists previously hypothesized sharks likely could not regenerate entire fins lost down to the fin base. Some shark species can regrow partial fins over a long time span, but full regeneration was thought impossible.
“For a shark to regain a near perfect version of a lost fin within a year is unheard of,” says marine biologist Dr. Leonardo Guida.
The discovery fundamentally changes scientific understanding of sharks’ wound healing capacities. It also sheds light on why sharks have survived five mass extinction events with little morphological change.
“Now we know sharks have an absolutely incredible capacity to heal from very significant injuries quickly,” Guida explains. “This contributes to their resilience in the face of rising fishing pressures, habitat destruction, and climate change.”
Mechanism Behind Rapid Fin Regeneration
Researchers theorize the rapid full fin regeneration is made possible by zones of thick skin near the fin base containing resting stem cells. When the fin tears off, specialized cells swiftly produce blastemal tissue and begin regenerating the intricate fin tissues.
Blood vessels, collagenous fin rays, nerves and skin must perfectly regenerate and integrate for the fin to become fully functional again. Silky sharks likely employ enhanced versions of the same genetic pathways land animals use to regrow lost limbs or tails.
Comparative studies of sharks’ wound healing genes and tissue regeneration mechanisms could have big implications for human medicine too. Further research is vital to elucidate the precise cellular mechanisms enabling this unprecedented feat. Monitoring the female shark in coming years can also reveal whether full function returns.
Impacts on the Shark’s Survival
Losing a dorsal fin has major impacts on shark survival since it impairs swimming performance and increases metabolic costs. Fins act as hydrofoils that provide lift and stability while reducing drag.
Researchers believe the female silky shark managed to survive this significant injury through behavioral adaptations. Healthy sharks tend to swim constantly to breathe, but injured sharks swim less to conserve energy.
The team spotted her near coral reefs, which likely provided ample hiding spots to rest and ambush prey. Such behavioral adaptability highlights why silky sharks remain abundant despite threats like boat strikes.
Response to the Remarkable Discovery
Scientists worldwide are hailing this as an incredibly exciting discovery that vastly expands knowledge of shark anatomy and resilience.
Many researchers are calling for improved shark conservation efforts in light of the findings. “It’s astonishing what sharks can recover from,” says Guida. “But we can’t rely on their self-healing abilities – we urgently need stricter fishing regulation and bycatch elimination to protect shark populations.”
Others say the research should spark the development of innovative wound healing treatments for humans. “If we can uncover the secrets behind the shark’s regenerative powers, surgeons could apply this knowledge to improve recovery from terrible injuries,” explains regenerative medicine expert Dr. Yui Cleynen.
Overall this unexpected documentation oddly caught on camera demonstrates there is still far more to discover about the incredible biology enabling sharks to persist for over 400 million years. It serves as a timely reminder of why we must strive harder to coexist with these magnificent ocean creatures.
| Injury Date | Re-Sighting Date | Elapsed Time | Fin Regrowth |
|---|---|---|---|
| October 2021 | December 16, 2022 | ~14 months | Nearly complete |
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