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Jellyfish Swimming Is Mixing the Oceans
eviltangerine writes "A new article from LiveScience suggests that marine creatures, such as the jellyfish, may contribute as much to ocean mixing as wind and tides. Wired is also covering the story and includes a video of the jellyfish in action. From the article, 'The mere act of swimming implies that some water travels with the swimmer,' said CalTech engineer Kakani Katija, co-author of the study in Nature Wednesday. 'Drift applies to all animals, to anything with a body.' No word yet on when the jellyfish blender is to debut."
Unless the swimmer is frictionless, their sides drag some water along with them. Yes, water must be displaced backwards, but it's not false that "some water travels with the swimmer".
10 PRINT CHR$(205.5+RND(1)); : GOTO 10
6 percent of ocean mixing is caused by the thrashing of swimmers in the process of being devoured by great white sharks. 18 percent of these are being eaten by the same shark that killed their father.
The densities of sea life in the past is apparent in the history of its harvest. Were the oceans more prolific because of the amount of fish mixing? Mixing creates more interface, so wouldn't that affect tiny organisms because they get more exposure on the food chain?
I recently read history of herring runs spawning in the Salish Sea so abundantly that the water was white, and that eggs were laid on everything in the water, such that they could be collected simply by submerging cedar branches. Not to mention historical quantities of fish all over the world...
Just heard a flying astronaut again describing how thin a veil the atmosphere is and I realized that for how big a volume the earth is, its livable surface area(biosphere) isn't really that large at all. *duh* but I never connected spherical geometry (area vs volume) and the concept of how profoundly we could affect our environment when the earth is soo big.
I mean, I know headlines can't convey everything, but it seems a few leaps have been made...
Exactly. I mean isn't that why ships and trucks travel in convoys?
Not a physicist but a physician. This makes sense - since it's roughly same way blood moves in blood vessels. Flow along the wall of the blood vessel is minimal. The greatest flow is in the center of the vessel, with diminishing flow the closer you get to the wall. That's why flow increases dramatically in larger blood vessels (it's a function of the fourth power of the radius - called the LaPoiseuille equation).
Again I'm no physicist, but I assume that if you have something pushing a fluid through a medium, you could define two boundaries that are not movable - the solid thing doing the pushing, and looking further and further out eventually you reach a "column" of water where the force does not get transmitted and is thus also static. Although it would be hard to get laminar flow in this scenario, it's not hard to imagine the greatest flow being generated where the greatest pressure change is - ie somewhere in the middle of the area described. The pressure change (and thus the flow) will be minimal where the static "walls" are, be they "real" (as in a solid fin, or an arm) or "not real" as in a non moving column of water.
Seven puppies were harmed during the making of this post.