why are there more small animals than large animals?

[Raize]

Anyone have any ideas or articles I can take a look at?

[nietzschefan]

They require less energy(food) generally...

[Raize]

i also think they are more specialized

is there any scholarly articles that address this issue? maybe from ecology

[Fraggle Rocker]

Thermodynamics. Surface area available for dissipating waste heat increases as the square of linear dimension. Whereas the mass of tissue creating the waste heat increases as the cube of linear dimension. In other words, if an animal grows twice as large in any one dimension, it has eight times as much heat to dispose of, but only four times a much surface area. Eventually it reaches a point where it's difficult to maintain an efficient metabolism.

There's a reason that the world's largest animals were reptiles. They're cold-blooded, meaning they don't generate internal heat. The only mammalian exceptions are the whales, and they live in an aquatic environment which very efficiently conducts and convects away their waste heat. Really big mammals like hippos and elephants spend a great deal of time either in the water or pouring water on themselves.

During the ice age, mammalian "megafauna" did exist, but only in the coldest latitudes. Woolly mammoths and woolly rhinoceros were all enormously larger than their present-day cousins. Size is an advantage in freezing weather, and today the largest bears (polar bears) live in the arctic.

[iceaura]

There's a book: "Why Big Fierce Animals are Rare". Library.

One way to look at it: There's only so much life support available in a given area. You can make ten elephants with it, or ninety thousand mice. More likely, one elephant and 81 thousand mice.
There's a reason that the world's largest animals were reptiles. Dinosauers. Their actual coldbloodedness is up for debate - some definitely weren't, apparently.

Many dinos had large sails or fins, huge flat crests and head ornaments, etc - there's been speculation (and data) that these things were for dissipating heat.

[Raize]

Thermodynamics. Surface area available for dissipating waste heat increases as the square of linear dimension.Eventually it reaches a point where it's difficult to maintain an efficient metabolism..

Very persuasive argument FR, thermodynamics definitely plays a big part. I wonder what the argument about environmental restraints would be.

[Raize]

There's a book: "Why Big Fierce Animals are Rare". Library..

Thanks I just reserved it, gonna pick it up from the library tomrrow.

[pjdude1219]

and larger animals require larger habitats as humans destroy animal habitats the is more pressure on larger species so they die off quicker

[S.A.M.]

Anyone have any ideas or articles I can take a look at?

They're faster and harder to kill. They can have more babies. They have shorter lifespans. They eat less.

[Starthane Xyzth]

During the ice age, mammalian "megafauna" did exist, but only in the coldest latitudes. Woolly mammoths and woolly rhinoceros were all enormously larger than their present-day cousins..

No they weren't. Common woolly mammoths (http://en.wikipedia.org/wiki/Mammoth#Size)were probably a bit smaller than the Indian elephant on average (after all, they had less food available); only the more ancient Imperial mammoths grew considerably larger than modern elephants. Woolly rhinos (http://www.crystalinks.com/woollyrhino.html) were comparable in size to the living white rhinoceros, although their horn was certainly longer (if the species had survived until modern times, that horn would have become deadlier to its bearer than to any other animal.. :( ).

Plus, there were also megafauna in the warmer parts of the World: like the giant ground sloths of South America and the diprotodon (http://www.abc.net.au/science/ausbeasts/factfiles/diprotodon.htm) of Australia.

[pjdude1219]

simple rabbits well f*** like bunnys

[Wisdom_Seeker]

because they can´t evolve with us in the way

[mikenostic]

There is speculation that size is the reason that Neanderthals died out and us smaller humans survived.

[one_raven]

because they can´t evolve with us in the way

You have a point.
You can feed a lot more people with the meat from one Bison, than 1,500 mice, so hunt Bison.

[Baron Max]

and larger animals require larger habitats as humans destroy animal habitats the is more pressure on larger species so they die off quicker

That's true. But even without humans around, the larger habitat requirement would necessarily limit the numbers of larger animals. They simply require more food, more space, more water.

Baron Max

[GeoffP]

There is speculation that size is the reason that Neanderthals died out and us smaller humans survived.

I think we probably just wiped them out.

[Wisdom_Seeker]

That's true. But even without humans around, the larger habitat requirement would necessarily limit the numbers of larger animals. They simply require more food, more space, more water.

Baron Max

Dinosaurs did it, they were huge MFs

[Baron Max]

Dinosaurs did it, they were huge MFs

Dinosaurs did ...what???

And why do you think all dinosaurs were "huge MFs"?

Baron Max

[mikenostic]

I think we probably just wiped them out.

According to this site, we're both right and wrong;

http://www.science-spirit.org/archive_cm_detail.php?new_id=317

But I read a couple other websites that state different. One states that climate change did it. Another states a bunch of different shit:
http://www.newscientist.com/article.ns?id=dn7221

I guess we'll never know!
http://www.deletetheweb.com/unstuck/ren-or-stimpy.jpg

[Wisdom_Seeker]

Dinosaurs did ...what???

And why do you think all dinosaurs were "huge MFs"?

Baron Max

They grew up to be very, very big.
Not all of them, but many of them man.

http://www.worsleyschool.net/science/files/supercroc/crocpic6.JPG

"The giant plant-eating Turiasaurus riodevensis, recently discovered in northern Spain, measured up to 120 feet (37 meters) in length and weighed as much as 48 tons, scientists say."
http://news.nationalgeographic.com/news/bigphotos/images/061221-giant-dinosaur_big.jpg
http://news.nationalgeographic.com/news/bigphotos/15087612.html

http://www.twoguysfossils.com/images/pic_torvosaurus_skeleton.jpg

[Wisdom_Seeker]

http://www.enchantedlearning.com/tgifs/Trex_bw.GIF

http://www.crystalinks.com/dinobig406.jpg

[Baron Max]

They grew up to be very, very big.
Not all of them, but many of them, man.

How many? And how many of each specie?

Without knowing that, nothing you've said so far makes any sense, does it?

Baron Max

[peta9]

http://www.twoguysfossils.com/images/pic_torvosaurus_skeleton.jpg


Well, that's clear evidence of a hello kitty universe. How sweet! God must be such a nice and good guy.

[pjdude1219]

There is speculation that size is the reason that Neanderthals died out and us smaller humans survived.

we were far more agressive also we devolveped lanuage befaore they did

[Baron Max]

we were far more agressive also we devolveped lanuage befaore they did

Well, that's all rather speculative, ain't it? I mean, thousands of species have disappeared from the planet over the millions of years, it can't all be because early man was more aggressive and developed language.

Although I understand people's desire to know things, "Shit happens" isn't such a bad explanation until we have some conclusive proof otherwise. If everyone on Earth began to specualate as to causes of things, we'd sure have a lot of "theories", wouldn't we?

Oh, wait, speculation without any evidence or infor is one of the things humans do best, ain't it? (Sorry, couldn't resist!)

Baron Max

[pjdude1219]

i figured reasonable people would infer i was onlt talking about hominds in this instance

[Baron Max]

i figured reasonable people would infer i was onlt talking about hominds in this instance

Interesting that you say that. I was talking about hominids, too ...or didn't you read my post?

Baron Max

[pjdude1219]

i think we have wandered off topic

[Wisdom_Seeker]

i think we have wandered off topic

Well, the topic said: "why are there more small animals than large animals? "
and some people argued that bigger animals need more food, space, etc...
And there had been bigger animals in a prehistoric past, so there goes that theory...

[spidergoat]

Any given amout of land will support more small animals than large, more herbavores than predators. That is a constant even when there were dinosaurs.

[Wisdom_Seeker]

Any given amout of land will support more small animals than large, more herbavores than predators. That is a constant even when there were dinosaurs.

I stand corrected, you are right.

[River Ape]

Well, look at it this way: Why are there more grains of sand than large boulders?

[Just_Not_There]

....

[Chatha]

They require less energy(food) generally...

Good idea

fun fact: whales can live up to 200 years

[Baron Max]

Well, look at it this way: Why are there more grains of sand than large boulders?

I don't know ....but are there more grains of sand than boulders?

Baron Max

[fatandlazyfool]

I've been considering the ration of large animals to small ones lately with a startling idea. There are less large animals because it takes them longer to birth, mature, reproduce and finally die. The life span is undeniably longer for an elephant than a hare. Now, think of what this means in each life cycle. There would be no advantage to the evolutionary stand-point for longer lives, now would there? But what about an ecological one? Besides genes, each animal holds dozens of different miniscual symbiotic relationships. Some are only helpful for the carier and harmful to others while vice versa for other times.
The point I'm getting at is that with all the larger animals being removed (larger being relative to humans, our perspective, the biggest population difference) in the last thousand years, what about the antibiotics that these larger animals held onto? Or maybe the balance of microscopic life that were given after birth?
But in response to the title, small and large are relative. Consider a 3 dimensional chart over time of the size and population of all animals (size > 1 cm), calculate a usable formula and take the center of gravity for it. Heh, just messing. But really, that would give you the reason...it all balances out to about the same point.
It's the circle of life (I love the Lion King...)
Scott

[valich]

Think Gravity. Some sea turtles can live two hundred years. Hydra (Cnidarians) can eternally regenerate, thus live forever.

[Smellsniffsniff]

The reason for the small animals is that we can take the most effective genes in every area, alter them and put them in a totally new lifeform that we let evolve by itself.

[valich]

aka, the eternal reign of Bacteria, Archaea and other simple protists when we all go extinct.

[Starthane Xyzth]

Didn't they have their day (or rather, their 2 billion years) of dominance BEFORE muticellular life popped up? Who knows, perhaps they will reign again one day. One of my university lecturers used to say that viruses will ultimately snuff out all other life on Earth - it's just a question of when.

[Orleander]

link (http://media.www.stateronline.com/media/storage/paper867/news/2007/03/01/ScienceAndTech/Americans.No.Longer.Tallest.People.In.World-2750128.shtml) Well, some humans are getting smaller. Namely Americans. Are we changing our own evolutionary destiny?

Americans no longer tallest people in world

LINCOLN, Neb. (U-WIRE) - It's official: Americans are no longer the tallest people on Earth. That honor now goes to Europeans, including the Dutch, Norwegians, Danish and Germans.

According to the Annals of Human Biology, Europe has overtaken the United States in the height department, a distinction the Americans had for the last 200 years.

In the United States, the current average height of an adult man is 5 feet, 9 inches, and for an adult woman, it is 5 feet, 3 inches, according to the Centers for Disease Control and Prevention.

In the Netherlands, though, men average 6 feet tall while the average woman is 5 feet, 7 inches, according to the Leiden University Medical Centre in the Netherlands.

Though there are many reasons for the disparity in height, the Annals of Human Biology suggest the shift in growth trends might have something to do with the amount of junk food Americans consume in comparison to Europeans.

Jennifer Snyder, a marketing specialist at the University Health Center at the University of Nebraska-Lincoln, agreed that the eating habits of Americans could have some effect on growth patterns.

"We (Americans) eat a lot more preservatives and additives (than Europeans), and the food is processed differently here," Snyder said.

Another reason why Americans are on average shorter than Europeans could be the result of more pollution in the air, Snyder said.

Although Americans as a whole are getting shorter, some are looking for ways to combat shortness.

In 2003, the Food and Drug Administration approved the use of synthetic growth hormone for youth with idiopathic short stature, or shortness for no apparent medical reason.

The treatment consists of an injection every day for many years, but the procedure is expensive, not usually covered by insurance companies and sometimes yields disappointing results - the average increase in height is about two inches.

While being extremely short can be a hindrance in everyday life, not everyone who uses growth hormones does so out of necessity. Many patients who opt to take a growth hormone choose to undergo the therapy for cosmetic reasons.

"For some people, taking it is more of a self-esteem issue," Snyder

[decantemix]

It has to do with predator-prey relations. You have to have a support system, on which the bio-sphere can sustain itself. As the larger predators expand in numbers, the prey begins to dwindle, and then the larger cannot sustain on the given resources.

[Raize]

Thermodynamics


Predator-prey relations

Longer generation times
- law of allocation
- slower rate of adaptation

Larger animals require larger habitats and more resources
- Any given amout of land will support more small animals than large

[Fraggle Rocker]

It's official: Americans are no longer the tallest people on Earth. According to the Annals of Human Biology, Europe has overtaken the United States in the height department, a distinction the Americans had for the last 200 years. Though there are many reasons for the disparity in height, the Annals of Human Biology suggest the shift in growth trends might have something to do with the amount of junk food Americans consume in comparison to Europeans.This is just the Melting Pot at work, isn't it? Until a few decades ago, America's gene pool came primarily from those tall countries: England, Scotland, Ireland, France, Germany, Holland, and Scandinavia. Now we're having a wave of immigration from places where people aren't especially tall, like Latin America, and from places where they're downright short, like East Asia. It isn't just height, look at what's happening to clothing sizes: The big department stores have to carry ladies' dresses in Size 2.

We aren't getting shorter. Short people are coming to live with us so their children can be taller. :)

[Orleander]

I thought since America is getting fatter, they were eating more but not better. You need vitamins and healthy food to grow.
I never considered immigration.

Are people from island countries smaller because they have a smaller environment?

[iceaura]

This is just the Melting Pot at work, isn't it? Until a few decades ago, America's gene pool came primarily from those tall countries: England, Scotland, Ireland, France, Germany, Holland, and Scandinavia. Now we're having a wave of immigration from places where people aren't especially tall, like Latin America, and from places where they're downright short, like East Asia. That has recently been shown to not explain the trend.

I'll try to find a link, but a few people have done some exhaustive data mining and concluded that Americans really are getting a bit shorter, and even more dramatically not getting taller as Europeans are.

After all the immigration and ethnicity and whatever has been allowed for

(America is not the only country with lots of short first generation immigrants, and first generation is all that matters - by the second and third generations, after allowing for income status pretty much every ethnic group is the same average height in any given country)

Europeans are now taller than Americans, in general, and the gap is widening.

The strongest correlation is with income inequality. Countries with large inequality of income have shorter citizens.

Another, smaller, correlation is with junk food.

edit in: http://en.wikipedia.org/wiki/John_Komlos A start for the intrigued, with literature citations.

http://www.newyorker.com/archive/2004/04/05/040405fa_fact Expository article