Coomera shark eats prop

[wessel]

This was takenfrom wikipedia

"More scientifically, a sacrificial anode can be defined as a metal that is more easily oxidized than the protected metal. Electrons are stripped from the anode and conducted to the protected metal, which, for this reason, is forced to become the cathode. As a result, the protected metal is prevented from corroding. One example is the galvanic anode used in a cathodic protection system, where the intended purpose is to prevent corrosion of the protected metal (such as a ship's hull, an oil pipeline, or a hot-water heater's tank) by being more electronegative than the desired metal. Commonly used metals for such protective purposes are zinc, aluminum and magnesium."

Hope it makes sense. Keep in mind that the current here is measured in millivolts, and sharks can detect it. Same as with stingrays that can detect the current in the muscles of a shrimp buried in the sand.

Wessel

[Fishin_Dan]

Of course! Cheers for that Wessel.

That does make sense. After having done electronics & chemistry previously you would think I should've remembered it... Damn forgetful brain!

[MagicRik]

The ampullae of Lorenzini are small vesicles and pores that form part of an extensive sub######### sensory network system. These vesicles and pores are found around the head of the shark and are visible to the naked eye. The ampullae detect weak magnetic fields produced by other fishes, at least over short ranges. This enables the shark to locate prey that are buried in the sand, or orient to nearby movement.

Recent research suggests that the ampullae may also allow the shark to detect changes in water temperature. Each ampulla is a bundle of sensory cells that are enervated by several nerve fibers. These fibers are enclosed in a gel-filled tubule which has a direct opening to the surface through a pore. The gel (a glyco-protein based substance) has electrical properties similar to a semiconductor, allowing temperature changes to be translated into electrical information that the shark can use to help detect temperature gradients.

Hope that helps some more

Rik

[MagicRik]

Did it sound like i knew what i was talking about?
Cos if someone would like to till me what all that means that would be great

[gogecko]

Sounds fine to me rik. I reckon theres a lot of animals that have senses we dont understand. Ive had a sneaky feeling that pidgeons navigate by EMF too, as they seem to follow grid lines or lay lines when navigating. It may be that beached whales have an issue with EMF disturbances too, possibly caused by earthquakes or sunspots? One day we will find out more.

My problem is that I dont understand how anodes and cathodes create EMF. Im sure the answer is on google somewhere when I get time to look into it.

I reckon the comment about the boys running aground and blaming the shark for the damage was funny. Most bull sharks in the Coomera arent any gigger than 3-4 ft long.

cheers
Andrew

[MagicRik]

Ive been looking on google and dont seem to be able to find the reason why things make EMF's, but i'ver im going crazy or i remember it to be somthing to do with friction. Like with a balloon being rubbed on something you get static or van de graph genarater same thing I think

thanks Rik

[fishingbarry]

I was told by an old salty once that sharks will hit the prop if your anchored up and there is a bit of current ,motor in neutral the prop may spin slowly and send out a noise and flash that can attract the bities. Might be something in that with the combination of the electrolysis.
Cheers
Barry

[cuzzamundi]

There are decent bullies in there. only sharked around there a coupla times, but we've pulled one out near 8ft. kn ow a bloke who got a small 6ft tiger in the logan too. have caught a few juvie scalloped hammers in there too. so there are a few species around in those systems. never known a bully to attack a prop though, but cant write it off. we had a tiger go our prop near the goldy two years ago. didnt damage it, but crikes gave us a fright. beautiful girl she was - easy 12 ft. ah crikes, why arent i out there?!

cuzza

[Dirtysanchez]

Guys I have also heard from one of my Electronic guru buddies that the signal that comes from your sounder is similar to what dolphins put out when they are using their sonar to communicate and / or find fish schools.

He said it would be advisable to turn off the sounder once you identified an area you wanted to fish and had anchored. I think this could be feasible, anyone heard similar ?

[MagicRik]

Its called "echoe location" the thing your talking about with the dolphins.
It works my mapping out your surrounding with sound.
A dolphin makes a clik in its mouth that then travel out to the fish and he then times how long it takes for the sound to bounce back to him.
By doing so he know how far the fish is away from him and where to find it.
Ive seen blind people use the same thing with a clicker under there tounge.