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Of course not, but each species has dimorphism (or lack thereof) that is apparently beneficial to that specific species' niche and evolutionary development along with sexual selection in many cases.
I really cannot fathom how different species (no matter what the enviornment is) produces differences in the sexes. While i understand the different roles of the sexes, I do not understand why some female species are bigger.
Do you mean you don't understand how the female and male of the same species can look so different? Because the answer to that is gender related genes (from the chromosome only the males get, which causes them to be male instead of female - this is determined at conception) and various hormone influences in the growing/adult animal.
As to why some females are the bigger of the species, Hespera has tried to explain that this is determined by whatever has worked in order for the species to have continued to reproduce successfully. Sometimes a big female helps survival - sometimes it does not.
Also, there is a certain amount of difference in the reproductive strategies of male and female - sometimes they even conflict, like in the case of the insect (I can't recall its name right now - old age!) species in which the male literally stabs the female's abdomen with his sperm depositor, wounding her, sometimes fatally, in order to have the best chance of his sperm being the first and only. Also with male lions which kill the cubs of a pride if they chase away the old lion - this is against the interests of the females, whose genetic successors are lost, and forces them to put energy into having more cubs.
Basically it was this. With deep sea fish, food is very scarce. Temp is near freezing, total darkness. the fish are small with weak watery muscles,; they dont move around much, they live as ambush predators. A single meal can last for many months, and it probably will have to.
In some types the males exist only as tiny (maybe 1% the saie of the ffemale) parasites permanently fused to the female.
If they were the same size as the female, then half of the very limited food supply would go to non egg laying individuals, and too, energy that is in short supply might be used looking for a mate.
So! twice as many egg layers as if they were not bigger than the male.
but like I said before, every creature has its own story, its own set of circumstances.
Do you mean you don't understand how the female and male of the same species can look so different? Because the answer to that is gender related genes (from the chromosome only the males get, which causes them to be male instead of female - this is determined at conception) and various hormone influences in the growing/adult animal.
No, I understand how they look different.
Originally Posted by Bombila
Also, there is a certain amount of difference in the reproductive strategies of male and female - sometimes they even conflict, like in the case of the insect (I can't recall its name right now - old age!) species in which the male literally stabs the female's abdomen with his sperm depositor, wounding her, sometimes fatally, in order to have the best chance of his sperm being the first and only. Also with male lions which kill the cubs of a pride if they chase away the old lion - this is against the interests of the females, whose genetic successors are lost, and forces them to put energy into having more cubs.
I know why male lions kill but the other poster said that the reason for the big group is to protect their young which doesn't apply with female lions
Basically it was this. With deep sea fish, food is very scarce. Temp is near freezing, total darkness. the fish are small with weak watery muscles,; they dont move around much, they live as ambush predators. A single meal can last for many months, and it probably will have to.
In some types the males exist only as tiny (maybe 1% the saie of the ffemale) parasites permanently fused to the female.
If they were the same size as the female, then half of the very limited food supply would go to non egg laying individuals, and too, energy that is in short supply might be used looking for a mate.
So! twice as many egg layers as if they were not bigger than the male.
but like I said before, every creature has its own story, its own set of circumstances.
thanks for your post.
If this method entails survival, why wouldn't all deep water fish have this same method (big female, little male)?
I dunno! Deep sea fish are far from my specialty, but I'd guess that in most or all of the known species the female is in fact much bigger.
For male salmon btw, there can be an advantage to being small. With king salmon, young males a tenth the size of the other fish can dart in and frtilize some eggs while the big guys are duking it out.
In your initial post, you explained only one so I was referring to that one.
Ah, now I got ya
So then, on with my response
Originally Posted by ke1985
I believe all the big cats (excluding the lion) do not apply to this concept yet the female is smaller.
This also applies to all bear species.
Why wouldn't this concept apply to them?
Well, off the top of my head (without digging into any research) it might be due to the fact that they are apex predators. The blue whale is not. Now I know you might be thinking "But what of the Spotted Hyena? They are also apex predators and the females average 20 lbs heavier than the male". Of course, this is a fact, and one that I havent dug into much.
So let's see, what have we examined? The fact that female blue whales are larger than males (and the possible reason why), the fact that large cat and bear females are smaller than the males (and one possible reason why), and the fact that another apex predator has larger females than males. Give me enough time and I can probably find out the "why" on that.
(ETA- It may have something to do with the fact that their clans are led, unlike other hyena species, by alpha females. Hence larger females are beneficial to the species population. But right now Im just spouting off the top of my head, seeing as how I haven't done any digging yet)
So that's what we've examined so far, now what have we learned? That sexual dimorphism takes different forms among different species for different reasons, and the "reason" of one species may not be (heck, probably won't be) the "reason" of another species, due to varying factors (niche, successful reproduction over a lifetime, sexual selection, etc etc etc).
Do you now see how wildly varying sexual dimorphism can occur, all the while explained (at least tentatively) by the Theory of Evolution?
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Last edited by corvus_corax; 3rd July 2009 at 12:49 AM.
Reason: Hyena info
I know why male lions kill but the other poster said that the reason for the big group is to protect their young which doesn't apply with female lions
It works for the females as long as their male is big and strong and able to chase other males away. Also, lion behaviour is very complex. Sometimes a pride of females will remain without a male for a short time, during which they will fight off any male to prevent their cubs being harmed. Sometimes a pride will have more than one adult male coexisting.
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Originally Posted by ke1985
I never said "always" but generally being bigger is better.
Nonsense. Generally speaking, SMALLER is better... which is why there are more small organisms than large ones. Its quite simply a matter of more efficient surface to volume ratio.
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Originally Posted by ke1985
thanks for your post.
If this method entails survival, why wouldn't all deep water fish have this same method (big female, little male)?
Because not all deep sea fish fill the same ecological niche. Sure, they share the same environment, but they live by different methods. So even though, I don't know, the deep sea angler fish and the 7 gilled shark live in the same environment, they fill wildly different ecological niches, thus the striking difference in body plan
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