2006-06-25 16:43:41 · 10 answers · asked by White Court 2 in Science & Mathematics ➔ Biology
One the individual level.
The salmon don't know they will die, and have no choice, they are programmed genetically to swim in the salmon run, just as we are programmed to drink water when we are thirsty..
On the species level. Swiming upstream leads to survival of salmon overall and in particular to ones that swim in the salmon run.
Swimming upstream to spawn and lay eggs is inherited genetically. . The salmon that swim upstream have offspring that inherit the same tendency.
Any salmon that for some reason doesn't have that genetic trait and doesn't swim upstream won't have any decendents-- and will die without leaving any offspring, so that that trait (of not swimming on the salmon run will die out quickly--since those having it will not reproduce) .
2006-06-25 16:53:23 · answer #1 · answered by lapaul 2 · 1⤊ 0⤋
I do not think all salmon die, I mean many do - stranded on the banks, eaten by bears, etc., but many still lay the eggs and then just swim downstream back to the shore.
Besides, the purpose of a living organism is not to survive at any cost, but to make sure that it's offspring survive. You are gonna die anyway, and bearing children is the only way to "immortality"
2006-06-25 16:48:26 · answer #2 · answered by Anonymous · 0⤊ 0⤋
Not all Salmon die after spawning. Some return to sea to grow bigger in size. It is their own instictual biological clock that tell them when it's time to make the final journey. Most of the time a battle against the body to return to where they spawn. When their journey is complete they molt and die so the fingerlings can eat off their decomposing bodies before becoming yearlings and taking their own trek to the ocean.
2006-06-25 16:53:39 · answer #3 · answered by mikey 4 · 0⤊ 0⤋
I don't think there is a definitive answer. I think it may be it's instinctive and they feel compelled. They lay their eggs, die and some how the nutrients from their bodies enriches that part of the stream for their hatchlings. Maybe they fertalize aquatic plants that the babies eat. IDK
2006-06-25 16:53:50 · answer #4 · answered by kllr.queen 4 · 0⤊ 0⤋
Lay eggs upstream
2006-06-25 16:47:27 · answer #5 · answered by MK6 7 · 0⤊ 0⤋
is their cycle of life, God created them like that,,,,is like humans when they smoke or take drugs or practice sex with no protection, they know they will die but they keep on doing so.really amazing!!!
2006-06-25 16:47:50 · answer #6 · answered by rivers_of_life 4 · 0⤊ 0⤋
Well, if they'll die anyways, they might as well enjoy their last swim.
Just a guess!
2006-06-25 16:47:56 · answer #7 · answered by T4Toyin 4 · 0⤊ 0⤋
it could be that they don't know the consequences of doing so, furthermore they use to procreate, and keep their species existing.
2006-06-25 16:57:14 · answer #8 · answered by Anonymous · 0⤊ 0⤋
Uhh... to save their species, maybe?
2006-06-25 16:46:34 · answer #9 · answered by boo_6917 4 · 0⤊ 0⤋
peer pressure
2006-06-25 16:47:37 · answer #10 · answered by starduster2 3 · 0⤊ 0⤋