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^{0.75Use
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
