Posturing Sharks | A video supplement to the magazine article

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Posturing Sharks | A video supplement to the magazine article

November 20, 2016 - 05:36

The agonistic display of the grey reef shark is so well known that some sources assume that all sharks behave that way. But in other species, such displays are not common, and vary a great deal, judging from the little information we have. This video shows a different type of agonistic behaviour, found in the blacktip reef shark. It was created to go with the article entitled Posturing Sharks, published in X-Ray Magazine

The close approach of the blacktip reef shark

This agonistic behaviour is not a display, but an attack stemming from rage or frustration. The camera was in my right hand, and when the shark slammed me, she hit it, making it hard to keep it focused on her as she whipped around me. She returned to slam the second time within a minute, this time rising up from beneath, with arched back. Accelerating with her tail, she rose straight upwards, to slam with the region of her back in front of the dorsal fin.

I had known this shark since she was a juvenile, and have no idea why she behaved this way that day. I often saw her and spent time with her in the lagoon, and she was always calm and treated me as the other sharks did.

When the group of three dozen sharks attacked the kayak, they always did so simultaneously. Something would trigger their outburst, and the entire company would attack. On many occasions, the heavy weight of the loaded boat was bashed with shocking force first one way, and then the other, as the sharks slammed it from multiple directions. Since they accelerated upwards from deep beneath, after slamming, they broke through the surface, which was replaced by sharks emerging at high speed, then twisting and shooting away together as more replaced them. For many minutes the slamming was continuous. After the heavy blows from the first sharks, more slammed right behind, and more behind them.

The action was usually facilitated by one or more sharks--not the biggest ones, but the boldest of the individuals. The females in their first year of reproduction were the most daring and reckless sharks, and during that period, it was they who would trigger the attacks, led by the most audacious among them, whereon the rest of the community joined in.

Sharks who are coming in to eat, however, do not signal their intentions in advance--you never see the shark that bites you.

Ila France Porcher

The painting above was an illustration originally done for my book. To subscribe to my newsletter, please visit my website.

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