|
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
will describe your animals in the Land Animals Assignment, including
their weight. From the animal's weight you can calculate how many
calories each animal needs per day.
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 KiloCalories per day. Of course, we
do not know anything about the needs of the life forms on other worlds,
although they, too, will need 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 =
K0.75
(BodyWeight)
|
This
means that
|
the
number of Kilocalories that your animal needs per day = |
K0.75
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 pounds (a puppy, maybe)
|
Kilocalories per day for a 5 pound mammal = |
K0.75
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 K0.75
.
|
Kilocalories per day for 5 pound mammal = |
K0.75 X (weight in pounds X 0.45)
24.7 X (5 X
0.45) =
24.7 X 2.25 =
55.57
Kilocalories |
What if your animal weight is in ounces? Instead of
weight in pounds, type
(Weight
in Ounces divided by
16).
Multiply
your
answer by 0.45 to make it into Kilograms.
|
Choose Your Animal Type |
K
|
K0.75
Use this number
|
| Reptile:
lizard, snake, 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
|
Non-passerine
bird: ostrich, chicken, non-perching 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.
NOTE
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. They would need to eat many more KiloCalories
than the calculations here show.
NOTE
The numbers of calories required by an animal are related
to the amount of energy. Extremely active animals, such as race
horses, or animals living in very cold climates, burn more calories than
animals that are moderately active.
|