The self-healing superpower of sharks
Not the ocean hero we deserve but the one that we need
No ocean animal is as misjudged or misunderstood as the shark. There are over 500 different species of these skilled hunters and yet all are reduced to a single description: brutal killers out for blood. The film ‘Jaws’ may have started the trend, but media stories of ‘serial killers’ ‘infesting’ waters and ‘savagely attacking’ beach-goers have further warped public perception of these misunderstood creatures. It’s as though they are in some way worse than any other predator animal, confused and looking for food. By amplifying the extremely rare attacks on humans, sharks have been demonised, when in reality there are so many reasons to love them and so many unique traits often overlooked.
For example, did you know sharks have very good eyesight? The back of their eyeballs have a reflective layer of tissue, so they are able to see exceptionally well in low light. Did you also know their skin has a sandpaper texture? Made from tiny teeth-like scales known as dermal denticles, these scales point towards their tail and help to reduce any water friction while swimming. And did you know the chance of dying by shark attack is 1 in 3,748,067?
Despite all of this, sharks have an unlucky combination of attributes working against them which has landed them on our bad side. And such negative connotations have led us to forget how important they are to marine ecosystems, as well as the fascinating feats of which they’re capable. Fascinating feats such as skin regeneration.
This evolution isn’t unique to sharks - starfish, sea cucumber, crustaceans and other ocean animals are adept in the art of cell regeneration, but sharks are the only fish with this remarkable ability to heal. As research is in its early stages, there is no definitive answer as to why sharks are able to heal so quickly and so effectively, but scientists believe it might have something to do with the distinct molecular biology of the mucus covering their skin. The skin of sharks secretes a mucus less acidic than that of bony fish and bears a closer resemblance to certain types of human mucus. This, and their bodies instant anti-inflammatory response to injuries, is just one potential answer scientists have unearthed, but as it hasn’t yet been studied under controlled conditions, given that it's quite a rarely observed phenomenon, we’re currently reliant on cases documented through research tagging and photography in the wild.
Sharks are naturally aggressive towards one another and it’s often during these interactions, when hunting and even when mating1 that sharks will receive a lot of injuries and so they’ve naturally evolved to heal quickly. But what their skin hasn’t naturally evolved to heal from is the barbaric assault from fish hooks, fishing lines, ghost gear, and injuries from any other human-produced debris or waste discarded in the ocean.
Even so, a recent case shows that sometimes shark skin can heal dramatically from even the most severe trauma. Photographed off the coast of Florida by local diver, John Moore, one particular silky shark recovered a large portion of its dorsal fin after a research tag was ripped from it. The satellite tag had been fitted to track the shark's migration, but only a few weeks later it was spotted with a horrific injury as the research tag appeared to have been viciously cut out by humans2. And yet, in a remarkable turn of events, just one year later the injured shark was spotted in the same waters with a dorsal fin reaching 87% of its original size, highlighting an incredible rate of recovery.
Silky sharks aren’t the only species capable of these levels of rejuvenation, blacktip and reef sharks have also been recorded healing swiftly from battle wounds, and whale sharks have the capability to repair extensive tissue damage by up to 90% in just 35 days. This impressive regeneration is crucial for an individual shark's survival, but also gives an explanation as to how they have evolved and survived as a species for hundreds of millions of years.
Often cast as the villains, sharks are in truth biological wonders with extraordinary healing powers. Our misguided fears, fueled by sensational tales, have allowed us to overlook their crucial role in the balance and overall health of the ocean. As we wake up to their brilliance, it’s time we stopped fearing sharks and started fearing a world without them.
Here at Beached we are building a community that can put our brains and resources together to highlight and fund solutions to the problems facing sharks. I hope you’ll join our humble community and click subscribe for free or support our work by purchasing the paid subscription.
All Beached posts are free to read but if you can we ask you to support our work through a paid subscription. These directly support the work of Beached and allow us to engage in more conversations with experts in the field of marine conservation and spend more time researching a wider breadth of topics for the newsletters. Paid subscriptions allow us to dedicate more time and effort to creating a community and provide the space for stakeholders to come together, stay abreast of each other’s work and foster improved collaboration and coordination.
One day Beached hope to donate a large percentage of the revenue from paid subscriptions to marine conservation organisations and charities to support their work too. Working together, we can reverse the degradation of our oceans and rivers.
Amie 🐋
Mating season can be particularly violent among sharks as males will bite the flank or fin of a female to get a secure position. It’s for this reason that female sharks have thicker skin.
It isn’t known why anyone would do this but as the intention obviously wasn’t to help the shark, researchers suggest it may have been the work of fishermen trying to stop conservation tracking or tagging.
So fascinating, thank you for sharing!
What amazing creatures. Thanks for keeping up the good work of helping us understand marine life that much more!