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Submitted on
November 26, 2005
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Based on an article by A. K. Dewdney ("Sharks and Fish on the Planet Wa-Tor"), this is a simple ecology simulation.

In this simulation, fish swim and reproduce while sharks swim, reproduce, and eat the fish.

About the parameters...

Breed Time: How old a fish or shark needs to be before it will reproduce. (On Wa-Tor, fish and sharks all reproduce by parthenogenesis, like amoebae.)

Starve: How long a shark can go without eating before it will starve to death.

Initial Population: The total number of each species with which to start the simulation.

World Size: The world wraps around so that, when a fish or shark swims off an edge, they come back on the opposing edge. The world can be anywhere from 2x2 to 20x15.

What parameters will provide a self-sustaining eco-system in which the sharks never hunt the fish to extinction but never starve to extinction themselves?

The original program Dewdney described in the article, back in the mid-1980's, used a simple text display in a grid with 0 . and * to indicate sharks, water, and fish.

Update: The simulation has been updated to remove the upper limit on world size. Very large worlds may cause the simulation to slow down but think about experimenting with the effect using larger worlds or long, thin worlds.
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HaoAsakura16 Featured By Owner Oct 26, 2014  Student Traditional Artist
Sharks: Breed=10 Starve=5 In Population=30
Fishes: Breed=1 Population=120

Size: 40x20

They were alive (sometimes almost enxtinct, but still alive) for a few hours until I just stopped it D:
101joee101 Featured By Owner Jun 14, 2014
I got An Infinite Cycle. Set:
Ini. Pop: 1
Starve: 1
Breed: Some really big number

Breed: 1
Ini. Pop: 4

Size: 2x2
AGV120395 Featured By Owner Jun 6, 2014
MaxterandKiwiKing Featured By Owner Nov 22, 2013  Hobbyist Digital Artist
The first time I played, the sharks went extinct at 804 seconds.
Kheelaia Featured By Owner Aug 22, 2013  Hobbyist Digital Artist
2014 seconds!
gonernow Featured By Owner Jan 14, 2013
Have you had any requests from fish scientists or biology teachers to do other simulations? This could be a very good learning tool.
SilverclawPetShop Featured By Owner Oct 18, 2012  Hobbyist Artist
1629 seconds!
Roxie-the-Charizard Featured By Owner Aug 21, 2012
Very interesting. In my case sharks got overpopulated, the fish almost got excint, but then most sharks starved to death so fish started populating again. And then sharks got overpopulated again, and it became a big endless cycle.
Detrimentality Featured By Owner Oct 30, 2011  Student General Artist
this is so cool
Proudgeek8 Featured By Owner Jan 5, 2011
it seems as if this could be rather useful for some science classes, because of the way it shows the basic predator-prey patterns (Predator rises, prey falls, predator falls, prey rises, predator rises......)
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