sharks-seals-fish-simple

1 collaborator

WHAT IS IT?

This model is a simplified version of the relationships between algae, fish, seal, and shark populations.

HOW IT WORKS

Algae patches can be eaten and regrow based on user input. Turtles use energy to move around the area, and gain energy by eating other populations. If they do not gain enough energy, they die. If they survive, they reproduce. Fish populations gain energy by eating algae. Seal populations gain energy by eating fish. Shark populations gain energy by eating both seals and fish.

HOW TO USE IT

You can set the initial populations of seals, sharks, and fish using the sliders. You can also set how quickly you want the algae to regrow. A larger regrowth time will result in slower growing algae.Be sure to hit "setup" whenever changing these settings. Then, click the "go" button everytime you wish to pass time and collect new data.

THINGS TO TRY

Consider setting different populations to their minimum and maximum starting levels and observe how these changes in one population can affect the other populations.

RELATED MODELS

The Wolf Sheep Predation model and Rabbits Grass Weeds model both use turtles and patches to represent interacting populations.

Comments and Questions

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Click to Run Model

breed[fish fishes]
breed[seals seal]
breed[sharks shark]

patches-own [ countdown]
turtles-own [ energy]

to setup
  clear-all
  reset-ticks

  ask patches [
    set pcolor one-of [green black]
    ifelse pcolor = green
        [set countdown algae-regrowth-time]
    [set countdown random algae-regrowth-time]]

  create-sharks initial-number-sharks
    [set shape "shark"
     set color blue
     set size 2
     setxy random-xcor random-ycor
    set energy random 10]
  create-seals initial-number-seals
     [set shape "seal"
      set color white
      set size 1.5
      setxy random-xcor random-ycor
    set energy random 10]
  create-fish initial-number-fish
       [set shape "fish 3"
      set color orange
      set size 1
      setxy random-xcor random-ycor
    set energy random 10]
end 

to go
  ask sharks
     [move
      eat-seals
      eat-fish
      death
      reproduce]
  tick
  ask seals [move
    eat-fish
    death
    reproduce]
  tick
  ask fish [move
    eat-algae
    death
    reproduce]
  tick
end 

to move
    rt random 50
    lt random 50
    fd 1
  set energy energy - 1
end 

to eat-seals
  let prey one-of seals-here
  if prey != nobody
    [ask prey [die]
      set energy energy + 1]
end 

to eat-fish
  let prey one-of fish-here
  if prey != nobody
    [ask prey [die]
      set energy energy + 1]
end 

to eat-algae
  if pcolor = green
      [set pcolor black
  set energy energy + 1]
end 

to death
  if energy <= 0 [die]
end 

to reproduce
  if energy > 0 and random-float 100 < 20
  [hatch 1 [ rt random-float 360 fd 1] set energy random 10]
end

There is only one version of this model, created about 1 year ago by Siobhan Sheehan.

Attached files

File	Type	Description	Last updated
sharks-seals-fish-simple.png	preview	Preview for 'sharks-seals-fish-simple'	about 1 year ago, by Siobhan Sheehan	Download

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