What
Do Food Pyramids Really Tell Us?
If
we know the Primary Productivity
of our plants, we can estimate how many animals that biome can support
and what sizes those animals can be.
You
should have described your animals in the Land Animals Assignment,
including their weight.
For
the purposes of this class we will assume that your animals have metabolic
rates similar to our earthly animals, which means that under similar
conditions they will need about the same number of calories per day.
Of course, we do not know anything about the needs of the life forms
on other worlds, although they, too, will need some energy.
Now
let's figure out how many KiloCalories (food calories) your animals
will need per day.
There
is a law called Kleiber's Law which can help us with this. The Formula
is
Kilocalories per day = K^{0.75}
(BW) 
This
means that
the
number of Kilocalories that your animal needs per day = 
K^{0.75}
multiplied by the Body Weight of the animal in kilograms. 
1 pound =
0.45 kilograms
Multiply
the number of pounds by 0.45 to get Kilograms
Now,
let's do it! For an animal that weighs 5 pound (a kitten, maybe)
Kilocalories
per day for a 5 pound mammal = 
K^{0.75}
X (5 pounds X 0.45 to convert to
Kilograms) 
Find
the type of animal from the chart below. Go to the last column on
the right and get K^{0.75}.
Kilocalories
per day for 5 pound kitten = 
K^{0.75}
X (weight in pounds X 0.45)
24.7
X (5 X 0.45) =
24.7 X 2.25
= 55.57 Kilocalories

Choose
Your Animal Type 
K 
K^{0.75
Use this number} 
Reptile 
lizard, snake, turtle  Cold Blooded
Ectotherm 
K
= 10 
5.6 
Marsupial
 kangaroo, opposum  has baby in pouch 
K
= 49 
18.5 
Placental
Mammal  dogs, cats  baby grows in mother 
K
= 72 
24.7 
Nonpasserine
bird  ostrich, chicken  nonperching birds

K
= 78 
26.2 
Passerine
bird  little perching birds  robins, sparrows 
K
= 129 
38.2 
NOTE
"Cold blooded" animals
that do not heat their bodies, (for example: lizards and crocodiles,)
require many fewer calories per day than endotherms, who are "warm
blooded". Warm blooded animals try to keep their bodies at a
constant temperature, and this uses many Kilocalories.
The numbers above do not apply to very
small animals such as mice and humming birds, that weigh less than
half a pound,. These animals have a large surface area compared with
their volume, and so lose a lot of heat.
Copyright © 1999, 2003.
Elizabeth Anne Viau and her licensors. All rights reserved. This material
may be used by individuals for instructional purposes but not sold.
Please inform the author if you use it at eviau@earthlink.net