How not to get eaten by a shark

In our current Planet Shark exhibition there is an entire section on how not to get attacked by a shark. Apart from physical protection such as steel cages and chainmail suits it features a number of chemical repellants, none of which are very effective, apparently. (In one case that’s primarily because the repellant is enclosed in the skin of a diving suit and only released when the shark bites trough it, which is of course a bit late…)

Electroreceptors in a shark's head
Electroreceptors in a shark's headSource: Wikipedia Commons

There is one technology, though, that can be effective in turning away an approaching shark, we are told. In the exhibition, it is represented by three different models of the Shark Shield equipment. However, the exhibit offers no explanation as to how this shield is supposed to work, so here’s an attempt to fill that gap:

Animals produce very weak electric fields whenever they move a muscle, and sharks are able to sense these electric fields with an array of electroreceptors called ‘ampullae of Lorenzini‘. To be of any use in prey detection, these receptors have to be extremely sensitive. But when the shark unexpectedly meets a very strong electric field, the resulting overstimulation causes the shark to turn away and avoid the waters around that field.

Shark Shield Scuba 7
Source: Shark Shield

Using two electrodes separated by a certain distance and powered by a battery, the Shark Shield equipment creates such an electric field around a person in the water. This creates an ‘exclusion zone’ extending 3-5m away from the person, which is still pretty close to get to a hungry shark, if you ask me. But even a short distance may make the difference between being bitten and just being scared to death.

However, how well this shark repellant really works probably depends on exactly how hungry the shark is…

1 response to How not to get eaten by a shark

  1. Andy Giger says:

    That would depend on whether I have a good reason to dive in the first place. The thing with repellents, whether they are citronella mosquito repellents, ultrasonic rat chasers or electric shark shields, is that they may repel, but that may not always be enough.
    If I want to spend an afternoon in the forest and I expect lots of mosquitoes, I put on some repellent, and I’ll be happy when I get only five mosquito bites instead of twenty.
    But I’m not sure that efficacy would be enough to face a bunch of hungry sharks with confidence…

    Like

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