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Blind sharks with science?


An out of left-field idea. It doesn't happen a lot, but one of the things people fear deeply is being bitten by a shark. Sharks sometimes bite surfers, because, it is suspected that 4 paddling arms lying on a surfboard triggers the "tasty seal" match in the shark's brain.

(Reportedly sharks don't actually like how we taste that much, and have spit out human limbs they bit off. I dunno, but somehow that's adding insult to major injury.)

Anyway, to stop this there are some products on the market. One is a set of decals in the black and white stripe patterns of poisonous fish sharks don't like to eat. Another is a set of electrodes that send out a strong electric field which sharks hate (they have electric sensing organs that most fish don't.)

Here's another idea, for all the surfboard shark repellant readers of my blog out there. Since the shark looks up at the board against the glittering surface, patterns on the bottom may not be enough. But what about new bright but low power LEDs? Possibly an animated pattern moving over the LEDs to say "not food" to the shark. First of all such light is highly non-natural (at least not from prey) and can be made to move in very artificial ways, or natural ways that signal non-prey. And today, the power for it is not very much. Here's where we need the advice of all the trained icthyologists reading the blog.


Hey, I'm not sure, but I think that (true to your subject line), sharks visually speaking are basically blind. I believe they sense prey by electric field and smell. Probably some sharkly combination of the two. So LEDs might not be the best bet. Keep in mind many sharks hunt by night.

It seems the lights might be similar to better documented glittering objects. My understanding is that sharks are not blind and are actually attracted to glittering objects much like other fish. Check out the fishing tackle at a bait store and see how they use reflective spoons to attract fish and entice them to bite. I've heard that sharks are more likely to attack people wearing jewelry because of the light reflections.

It's my understanding that sharks have poor visual resolution but high contrast and motion sensitivity (like most other fish). As a side note, beside surfers looking like retard seals from the bottom up, it has also been theorized that attacks may also be triggered by the sharp contrast of the sole of the feet dangling in the water that appear to look like fish in motion (the sole being usually very bright, pale white). Of course, surfers wearring booties have also been mumched on so...
However, sharks being the ultimate predators in our water, with very few evolutionary changes over the last million years (what a great design!), I doubt cheap tricks will do much to scare it off... and believe me I'd love to see it work (not on me), since I surf in CA a few times a week.

Contrary to popular belief, sharks have very good eyesight. they are better at seeing objects far away, but can up close well enough. they're eyes are 10X more sensitive to light than humans, and have layer inside their eyes called the tapetum cats. this reflects any light that comes in and allows them to see in low light.
sharks do not rely on eyesight to detect and locate food...rather they use smell, hearing and the electrosensory components of their senses...the ampullae of Lorenzini and the lateral line. therefore if it smells, sounds and is giving off the same electrical signals as their prey, there is more chance that they will have a go at catching something even if it doesnt look 100% right.

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