Phanerothyme Posted March 29, 2004 Share Posted March 29, 2004 Originally posted by mojoworking That one works better if you point out that sharks die if they stop swimming. No swim bladder, apparently, so they can't "hover" in the water and have to keep water passing through their gills that is also untrue, about sharks dying when they stop swimming. maybe true for some sharks but not all. What about Wobbegongs? Link to comment Share on other sites More sharing options...
Smiler Posted March 29, 2004 Share Posted March 29, 2004 You are 14,000 times more likely to have an accident involving a fridge than you are to win the jackpot on the National Lottery. Err, unless you haven't bought a ticket, when the odds are even worse. Link to comment Share on other sites More sharing options...
mojoworking Posted March 29, 2004 Share Posted March 29, 2004 Originally posted by Phanerothyme that is also untrue, about sharks dying when they stop swimming. maybe true for some sharks but not all. What about Wobbegongs? There's always an exception that proves the rule. I'm refering to regular sharks. They have no swim bladder, so when they stop swimming, they sink to the bottom. No oxygen passess through their gills. They die. Link to comment Share on other sites More sharing options...
Phanerothyme Posted March 29, 2004 Share Posted March 29, 2004 It may be true for some sharks but but to say all, or even most is an overstatement. Sharks are very slightly negatively bouyant on account of their enormous oil filled livers. So they will slowly sink to the bottom if they stop swimming but they won't necessarily die. Rather than evolve a swim bladder, sharks retained liver buoyancy, possibly because it allows them to traverse great depths without exploding, unlike bony fish with swim bladders. cat sharks, dogfish, and several others types, as well as all bottom living sharks, are able to pass water over their gills, they just don't use gill covers like bony fish do. Tiger sharks have been observed lying on the sea floor, just chilling out, without asphyxiating too. Link to comment Share on other sites More sharing options...
mojoworking Posted March 30, 2004 Share Posted March 30, 2004 Originally posted by Phanerothyme It may be true for some sharks but but to say all, or even most is an overstatement. Sharks are very slightly negatively bouyant on account of their enormous oil filled livers. So they will slowly sink to the bottom if they stop swimming but they won't necessarily die. Rather than evolve a swim bladder, sharks retained liver buoyancy, possibly because it allows them to traverse great depths without exploding, unlike bony fish with swim bladders. cat sharks, dogfish, and several others types, as well as all bottom living sharks, are able to pass water over their gills, they just don't use gill covers like bony fish do. Tiger sharks have been observed lying on the sea floor, just chilling out, without asphyxiating too. Like I said, there are exceptions, but it's true for MOST sharks. I know how important it is to you to be seen to be correct, but if you won't believe me, here's something I've cut and pasted from a website about sharks. http://www.sheddnet.org/ani_faqs_04.html#k Why do most sharks need to swim constantly? Sharks lack a swim bladder, the organ found in most other fishes to help them keep afloat. If a shark stops swimming, it will start to sink to the bottom. Once a shark has landed on the bottom, it is no longer pumping water through its gills. Without this water, the shark cannot get the oxygen it needs for respiration. Interestingly, a shark gets much of its buoyancy from its liver. There are some sharks, however, that do not need to keep swimming. The nurse shark is an example. It can actively pump water through its gills so it can rest at the bottom of the water and still breathe Link to comment Share on other sites More sharing options...
saxon51 Posted March 30, 2004 Share Posted March 30, 2004 Originally posted by markham That by the way is an area of land 60 miles x 60 miles, so we could easily flood Lancashire and most of Manchester. Sam Mig., if you're reading this, grab your chessboard and eyedropper and meet us on the Woodhead pass if they release you when your sanity certificate has been granted. Or if we only make it 250 metres deep we can flood an area of 120miles x 120 miles. Mmmmmm, that's about the size of Wales isn't it. Link to comment Share on other sites More sharing options...
march Posted August 5, 2004 Share Posted August 5, 2004 So how do Sharks sleep? Not very conclusive answer here: http://www.elasmo-research.org/education/topics/b_sleep.htm Link to comment Share on other sites More sharing options...
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