9 June, 2020 9 June, 2020

Shark Skin Will Blow Your Mind

Legs spread almost a meter wide. Each knee pressing down on a pectoral fin. Lactic acid building in my forearms from applying the downward pressure necessary to handle the 3+ m six-gill shark between my legs safely. Six-gills or as they are more commonly referred to ‘cow shark’s’ vertebra don’t calcify making them tricky to work with as this allows them to contort to the point they could bite the base of their tail (precaudal pit) or me. But that’s what happens when you handle sharks’ – teeth are always gonna present a hazard. 

What you might not be thinking about is that shark skin eating away at my inner thighs. Ladies and gentlemen, I introduce you to ‘shark rash’ a very real and painful eventuality of being a shark researcher.

Shark skin, characterized by its grey colour and rough tactile texture, is truly an exceptional piece of evolution. In fact, it is still widely debated amongst the scientific community as to what came first, a shark’s teeth, or its skin as the two are homologous in their structural makeup.

Unbeknownst to most, shark skin is made of a matrix of tiny, hard structures called dermal denticles or placoid scales. They have the same structure as all teeth with an outer layer of enamel, dentine, and a central pulp cavity, making tagging them (even the small buggers) a tall ask.

All of the spines of these denticles point backward, towards the tail, giving shark skin that sandpaper-like feel. Unlike fish scales that grow as the fish does, these denticles never get bigger, they simply become more numerous to accommodate for growth. Throwing it back to a time when peasants were being beheaded for eyeballing the king’s misses, knights used shark skin on the handle of their swords as it made for one helluva grip when going into battle.

Examples of dermal denticles from three different shark species

 

With a history spanning more than 400 million years, sharks can teach us a lot about speed and efficiency in the water. Researchers are trying to make artificial shark skin that would prevent the accumulation of algae and barnacles in the water — and even prevent bacterial growth when applied to hospital surfaces, a form of biomimicry.

But back to shark rash, the bitch of being in the field. Its terrestrial equivalent would be a laka roastie with the addition of urea being applied on the wound. Before you run away with this one, let me reel you in. I’m not saying that sharks take the piss when you handle them but rather that they produce urea, which is excreted through their tissue in order to keep them from turning into bokkoms in the salty seawater.

In 2017 I met a man whose livelihood rested on his ability to catch sharks for rich tourists so they could get that classic ‘big fish’ photo. Whilst on charter, with a bunch of Russian housewives on a getaway from their husbands who could probably hammer a nail into concrete with their fist, Hans lost more than his patience. After landing a sizey thresher shark, Hans received a PK from hell across the back of the calf from the thresher’s iconic whip-like tail which it uses to stun its prey. The result, Hans required a skin graft as the urea that contaminated his shark rash went full-on gangrenous.

The point of this column? Well a sharks a shark, they’re up early, biting things and chasing stuff reminding everyone that they’re a freakin shark so we might as well get to know them, not fear them and perhaps foster a better attitude toward protecting them.

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