What is a Shark a Shark repellant? How does it work?
89291
I just saw on the Discovery Channel that they have created a shark repellant.  This is a device that omits a frequency that the shark dislikes.  A scubba diver attached this to his tank and then the swimmer pushed a button that released the frequency...I guess sharks do most stuff because of vibrations and frequency in the water...it's kinda like their eyes.\n\nAnyways, scientists are hoping to develope this further so they can get rid of nets along the coast <which kill sharks, dolphins, and turtles>.
899492
depends if there are sharks under there with you
112480
Hello, Every subamarine contains ballast tanks that when the needs to sink  it takes in water, due to the pressure and weight the submarine sinks and goes underwater and is propelled through propellars. When it needs to rise to suface, it lets the water out slowly and air comes and fills its ballest tanks and the submarine comes to surface. \n\nThats' it works, more info, check the web
161088
The killer whale is so big that a shark would never be able to do any damage to it.  But at the same time a whale can't fight back.  So it would be a tie.
956438
Either a slick shark or a dolphin. Sharks are amazing creatures which live for hundreds of years and dolphins are just awesome
517749
Humans are not it's main source of food.  Therefore the shark would only attack a person if 1. was incited by a feeding frenzy 2. shark has not been able to get normal source of food for some time 3. the shark is confused by the shape, and takes an investigative bite.  A shark can easily kill a person, but usually after the initial bite they usually let go.  Very rarely are people actually killed and consumed by the shark.
393749
I haven't heard of any shark species being endangered.  I know "Jaws" author Peter Benchley was an advocate of their conservation (which was reported at the time of his recent death), but I was and am still unaware that there was a need for conservation.  The only shark species I know to be extinct is the Megalodon (the much larger ancestor of the Great White).
397671
They bash into their predators. they are actually quite strong. they kill sharks that way
1042893
The ones that actually adhere to the sharks are remoras. They're fishes belonging to order Perciformes, family Echeneidae, and they have a dorsal sucking disk with which they attach to sharks , but also to other bony fishes, turtles or marine mammals. These fish clean their "host" and feed on their leftovers.\nThis is what a remora looks like:\nhttp://www.amonline.net.au/fishes/fishfacts/images/enaucsh2.jpg\n\nThe other, more typical-looking fish with dark and light vertical stripes, are pilotfish. These also belong to order Perciformes, but to a different family, the Carangidae. Their scientific name is Naucrates ductor. They were called "pilotfish" because of the belief that they "guided" sharks. Actually, they're semi-obligate commensals of sharks, rays, other bony fishes and turtles, which means that they depend very much on them to feed on their leftovers.\nThis is what a pilotfish looks like:\nhttp://www.horta.uac.pt/imagdop/Servicos/Naucrates_ductor/035_s410_31.jpg
1183313
Well Boxergirl, I've been scuba diving for 28 years, and just as the surfer said, the best way to defend against a shark attack is to be aware of the shark to begin with! We did a live study on shark attack methods, and the results were very interesting. Almost all sharks will circle their targeted prey several times before attacking. They attack from below, getting an angle from below so that they give no warning. In the surf, and at the mouths of rivers and such, they come from the side, due to no visibility and most attacks on humans there are mistaken identity, because they don't actually see you at all. They bump into soft flesh, and bite in reflex, normally letting go as soon as they taste the blood. Our blood is not the same as marine life, so it's not something they actually like very much. But it can get them excited, so don't take it for granted that they won't attack twice. \n    In the event that you ARE attacked, stay calm, first and foremost! You will have a bad cut, or worse, so you do NOT want to get your heart to racing! If at all possible, locate the shark, and keep an eye on it, while you work at stopping or at least slowing the blood flow. Swimming calmly, not splashing or acting erratic, make your way towards shore, yelling loudly to let nearby swimmers know that you've been attacked. In the event that the shark returns, or makes another pass, you can use both hands and feet to kick and strike in the nose and eye regions. If you have a board, shove the nose of the board at the shark's eye region. Keep in mind that if you are bitten, other sharks may be attracted, so you are in a fight for survival, and there are no rules. You fight to win, no questions asked. \n    Like I said, I've been diving for 28 years, and even with all the sharks dives I've done (435), I've never been bitten. I HAVE had to ward several off when they got too nosey, but no bites. Good luck!!
257089
Depending on the fish there could be different obstacles. Certain sharks must continually swim to pass water over there gills to not suffocate. Also in certain shallow water mangroves oxygen depleted water can be another obtacle (except for the lemon shark which can survive better in low oxygen water). I also believe polluted water, such as oil spills and the like, can be perhaps the biggest obstacle of all the fish will face in the respiration process especially around coastal areas.
813666
There is 1 baby female living at Sea World San Diego, but I don't know if she's visible to the public. This little 7 footer currently has the record for surviving in captivity - 54 days as of 11/7/2006.\n\nGreat Whites don't survive after they're captured, and scientists are trying to figure out why. The previous record was 16 days back in August 1981.\n\nFor some reason, after about 10 days sharks stop eating, start swimming erratically, bumping off of walls, and eventually sink to the bottom of the holding tank, where they drown. If a shark doesn't keep water over its gills, it doesn't get any oxygen and dies.\n\nLots of things have proven to be involved - great whites can detect as little as 0.01 volts of electricity in the water. This transient voltage interferes with their guidance or feeding instincts and they batter themselves against the cage trying to get to the source of the signal. \n\nThe facility in San Diego has no electronics of any kind directly mounted on or near the tank. The tank is also significantly bigger than previous efforts: 1,000,000+ gallons. The researchers also took several days to acclimate the young shark in a fenced off area of the ocean, gradually reducing the size until it was the same size as its million gallon intended home.\n\nDespite years of research, very little is actually known about Great Whites. How deep they can go? What are their reproductive habits? How often do they give birth? Why are their movement patterns over a lifetime? All of these questions are still mysteries.\n\nGive it a few years. Once we get answers to some of the basic questions, we might be able to keep them in captivity. Hopefully we'll be able to not only learn from them, but protect them so our children and grandchildren can enjoy them, too.\n\nHope that answers your question,\nOdd
40627
the best "repellant" is a fan or gentle breeze as mosquitoes do not like moving air.small electrical mats, mosquito repellent vapour, and mosquito coil.
1085449
Animal face-off is a show that aired on the Discovery channel.  They took animals and used complex technology to imitate the natural skills of these predators and entered the data into a computer simulation using a terrain effect that was equally beneficial to both creatures.  In truth there are too many variables in life to know for sure.\n\n The shark won.  Quick attacks with devastating psi bite power and open water to move in.  The croc puts up the good fight but is outmatched against the most famous killer in the animal world.
630715
I do not know exactly what you are looking for here. I guess you have never seen "Jaws". \nGreat whites are killers. They usually bump prior to attacking to test the weakness of their prey. Since their skin is like sandpaper, in the process of bumping it can cut skin. \n\nSharks have very acute senses; they can detect smell (like blood & urine) & vibrations from far distances. This is one reason you should never swim in the ocean with a dog. Their swimming makes vibrations that sound like struggling, inviting sharks to attack. \n\nFor more information on sharks read " Twelve Days of Terror: A Definitive Investigation of the 1916 New Jersey Shark Attacks" by Richard G Fernicola (ISBN 1585745758) & "Close to Shore" by Michael Capuzzo(ISBN 0767904141).
1123272
Q: Can fish change their buoyancy? If so, how?\n\nA: Yes, many species of fish can change their buoyancy. There are four different strategies that fish use:\n\n1) incorporation of large quantities of low-density compounds in the body (i.e. oils and fats)\n2) generation of lift by appropriately shaped and angled fins and body surfaces during forward movement\n3) reduction of heavy tissues such as bone and muscle\n4) use of a swimbladder as a low density, gas filled space\n\nMany species of sharks use oils to regulate their buoyancy. The hydrocarbon squalene is a low density oil that is found in sharks and is believed to function in buoyancy control.\n\nSwimbladders allow for precise control of the fish's depth because the volume of gas they contain can be regulated quite easily. The idea behind the swimbladder is relatively simple. Air is less dense than water, therefore, air floats on top of water. In the same way, if you think of an oil spill, the oil floats on top of the water because oil is less dense. The swimbladder of the fish holds air, which allows the fish to be lighter in the water and making it more buoyant. If the fish lets air out of the swim bladder it will get more dense and begin sinking.
894325
NaCl or any salts?\n\nI don't know of any substance that "repels" a salt, other then a waterproofing.  Since salt dissolves in water you would likely have to repel the water, not the salt.