globals [ tocks bass-caught average-yield ]
breed [ algaes algae ]
breed [ sunfishes sunfish ]
breed [ bass a-bass ]
breed [ gar a-gar ]
breed [ anglers angler ]
turtles-own [ energy ]
algaes-own [ grabbed? ]     ;; to prevent two sunfish from eating the same pondlife
sunfishes-own [ grabbed? ]  ;; to prevent two bass from eating the same sunfish
bass-own [ grabbed? ]       ;; to prevent two anglers from catching the same bass


;*********************** setup **********************

to setup
  ca
  set tocks 0
  set bass-caught 0
  ask patches [ set pcolor blue ]
    
  set-default-shape algaes "pondlife"
  create-custom-algaes initial-algae-biomass    ;; create the algae, initialize their variables
   [ set color green + 1
     set size 1
     set energy random 10                       ;; create an initial population with a random distribution of energy
     setxy random-xcor random-ycor
     set grabbed? false 
   ]

  if initial-sunfish-biomass > 0 [                   ;; if no initial sunfish, skip instructions
    set-default-shape sunfishes "sunfish"
    create-custom-sunfishes initial-sunfish-biomass  ;; create the sunfish, initialize their variables
    [ set color orange
      set size 1
      set energy random 60                           ;; create an initial population with a random distribution of energy
      setxy random-xcor random-ycor
      set grabbed? false 
    ] ]
  
  if initial-bass-biomass > 0 [                ;; if no initial bass, skip instructions
    set-default-shape bass "bass"
    create-custom-bass initial-bass-biomass    ;; create the bass, initialize their variables
    [ set color magenta
      set size 2
      set energy random 100                    ;; create an initial population with a random distribution of energy
      setxy random-xcor random-ycor
      set grabbed? false
    ] ]
  
  if initial-gar-biomass > 0 [                 ;; if no initial gar, skip instructions
    set-default-shape gar "gar"
    create-custom-gar initial-gar-biomass      ;; create the gar, initialize their variables
    [ set color black
      set size 2
      set energy random 100                    ;; create an initial population with a random distribution of energy
      setxy random-xcor random-ycor
    ] ]
    
  if hours-fishing > 0 [                       ;; if no initial anglers, skip instructions
    set-default-shape anglers "angler"
    create-custom-anglers hours-fishing        ;; create the anglers, initialize their variables
    [ set color black
      set size 5
      setxy random-xcor random-ycor
    ] ]
  
  do-plot1
  do-plot2
  do-plot3
end


;************************ run ************************

to go

   set tocks tocks + 1

   if tocks = 465 [                        ;; calculate average yield during a period of 365 tocks (days)
      calculate-yield ]
    
   ask algaes [
      if random-float 100 < 25 [ set energy energy - 1.5 ]  ;; some algae loose energy with each "tick"
      reproduce-algaes
      death ]
    
  if initial-sunfish-biomass > 0 [
      ask sunfishes [
       move
       set energy energy - (1 + (count sunfishes / 100))
       catch-algae
       reproduce-sunfishes
       death ] ]
         
  if initial-bass-biomass > 0 [            ;; if no initial bass, skip instructions
    ask bass [
      move
      set energy energy - (1 + (count bass / 5))  
      if count gar > 0 [
       set energy energy - 5 ]              ;; make bass less efficient preditors than gar
      catch-sunfish
      reproduce-bass
      death ] ]
      
  if initial-gar-biomass > 0 [             ;; if no initial gar, skip instructions
    ask gar [
      move
      set energy energy - (1 + (count gar / 5))     
      catch-sunfish
      reproduce-gar
      death ] ]
      
   if hours-fishing > 0 [                  ;; if no hours fishing, skip instructions
      ask anglers [
      catch-bass ]]
    
   do-plot1  ;; plot "producers"
   do-plot2  ;; plot "consumers"
   do-plot3  ;; plot "biomass"
   
   if ((count algaes = 0) and (count sunfishes = 0)) [ stop ]
    
end


; ********************** move ********************

to move  ;; for fish
  rt random-float 50 - random-float 50
  fd 1
end


; ************************ reproduce *************************

to reproduce-algaes
   if sunlight > 0 [
     if (random-float 100 < (3 + (int (2 * sunlight - (count algaes)) / 3000))) [
     if (count algaes) <= (sunlight * 2) [
     hatch 1 [ rt random-float 360 jump 20 set energy 10 ] ] ]       ]            ;; spread the new algae around the pond
end

to reproduce-sunfishes
  if (count sunfishes) < ( (count algaes) / 10 ) [
  if energy > 120
   [ set energy ( energy / 2 )                  ;; energy of offspring will be 1/2 of reproduction energy
     hatch 1 [ rt random-float 360 fd 1 ] ] ]
end

to reproduce-bass
  if energy > 72 [
   set energy ( energy / 2 )                    ;; energy of offspring will be 1/2 of reproduction energy
     hatch 1 [ rt random-float 360 fd 1   ]  ]
end

to reproduce-gar
  if energy > 75 [
   set energy ( energy / 2 )                   ;; energy of offspring will be 1/2 of reproduction energy
     hatch 1 [ rt random-float 360 fd 1 ] ]
end


; *********************** catch prey ********************

to catch-algae
  let prey one-of (algaes-here with [not grabbed?])
  if prey != nobody
    [ set grabbed?-of prey true
      ask prey [ die ]
      set energy energy + 4 ]
end

to catch-sunfish
  let prey one-of (sunfishes-here with [not grabbed?])
  if prey != nobody
    [ set grabbed?-of prey true
      ask prey [ die ]
      if breed = bass                  
       [set energy energy + 100 ]
      if breed = gar 
       [set energy energy + 150 ]
    ]    
end

to catch-bass
  if tocks > 100 and tocks < 466 [
  let prey one-of (bass-here with [not grabbed?])
  if prey != nobody
    [ set grabbed?-of prey true
      ask prey [ die ]
      set bass-caught bass-caught + 1 ] ]
end

;; for instructional purposes the following code determines the average yield from fishing
      
to calculate-yield                                 
      if tocks = 465 and count bass > 0 [ 
      if hours-fishing = 0 [ set average-yield 0  ]
      if hours-fishing = 1 [ set average-yield ( count bass / 12 ) ]
      if hours-fishing = 2 [ set average-yield ( count bass / 3 ) ] 
      if hours-fishing = 3 [ set average-yield ( count bass / 12 ) ] 
      if hours-fishing = 4 [ set average-yield ( count bass / 24 ) ] 
      if hours-fishing = 5 [ set average-yield 0 ] ]
end

to death
  if energy <= 0 [ 
  die ]
  end


;; ****************** plot ********************
  
to do-plot1
  set-current-plot "Producers"
   if count algaes > 0 [
     set-current-plot-pen "algae"
     plot ((count algaes)) ]
end

to do-plot2
  set-current-plot "Consumers"
  if count sunfishes > 0 [               ;; prevent plotting of "zero line" if no sunfish
    set-current-plot-pen "sunfish"       
    plot (count sunfishes) ]
  if count bass > 0 [                    ;; prevent plotting of "zero line" if no bass
    set-current-plot-pen "bass"
    plot (count bass) ]
  if count gar > 0 [                     ;; prevent plotting of "zero line" if no gar
    set-current-plot-pen "gar"
    plot (count gar) ]
end

to do-plot3
  set-current-plot "Biomass"
  clear-plot
    if count algaes > 0 [
      set-current-plot-pen "algae"
      plotxy 0.5 ( count algaes )
      plotxy 0.55 ( count algaes )
      plotxy 0.6 ( count algaes )
      plotxy 0.65 ( count algaes )
      plotxy 0.7 ( count algaes )
      plotxy 0.75 ( count algaes )
      plotxy 0.8 ( count algaes )
      plotxy 0.85 ( count algaes )
      plotxy 0.9 ( count algaes )
      plotxy 0.95 ( count algaes )
      plotxy 1.0 ( count algaes ) ]
    if count sunfishes > 0 [
      set-current-plot-pen "sunfish"
      plotxy 1.5 ( count sunfishes )
      plotxy 1.55 ( count sunfishes )
      plotxy 1.6 ( count sunfishes )
      plotxy 1.65 ( count sunfishes )
      plotxy 1.7 ( count sunfishes )
      plotxy 1.75 ( count sunfishes )
      plotxy 1.8 ( count sunfishes )
      plotxy 1.85 ( count sunfishes )
      plotxy 1.9 ( count sunfishes )
      plotxy 1.95 ( count sunfishes )
      plotxy 2.0 ( count sunfishes ) ]
    if count bass > 0 [
      set-current-plot-pen "bass"
      plotxy 2.5 ( count bass )
      plotxy 2.55 ( count bass )
      plotxy 2.6 ( count bass )
      plotxy 2.65 ( count bass )
      plotxy 2.7 ( count bass )
      plotxy 2.75 ( count bass )
      plotxy 2.8 ( count bass )
      plotxy 2.85 ( count bass )
      plotxy 2.9 ( count bass )
      plotxy 2.95 ( count bass )
      plotxy 3.0 ( count bass ) ]
    if count gar > 0 [
      set-current-plot-pen "gar"
      plotxy 3.5 ( count gar )
      plotxy 3.55 ( count gar )
      plotxy 3.6 ( count gar )
      plotxy 3.65 ( count gar )
      plotxy 3.7 ( count gar )
      plotxy 3.75 ( count gar )
      plotxy 3.8 ( count gar )
      plotxy 3.85 ( count gar )
      plotxy 3.9 ( count gar )
      plotxy 3.95 ( count gar )
      plotxy 4.0 ( count gar ) ]
    
 end

; *** NetLogo 3.1.4 Model Copyright Notice ***
;
; (C) Copyright 2007 Western Michigan University
; Permission to use, modify or redistribute this model is hereby granted,
; provided that both of the following requirements are followed:
; a) this copyright notice is included.
; b) this model will not be redistributed for profit without permission
;    from Western Michigan University.
; Contact Western Michigan University for appropriate licenses for 
; redistribution for profit.
;
; *** End of NetLogo 3.1.4 Model Copyright Notice ***
@#$#@#$#@
GRAPHICS-WINDOW
886
72
1388
595
26
26
9.3
1
14
1
1
1
0
1
1
1
-26
26
-26
26

CC-WINDOW
5
610
1397
705
Command Center
0

BUTTON
37
10
106
43
setup
setup
NIL
1
T
OBSERVER
T
NIL

BUTTON
38
49
105
82
go
go
T
1
T
OBSERVER
T
NIL

PLOT
257
299
867
596
Consumers
time   (days)
biomass (kg/ha)
0.0
100.0
0.0
100.0
true
true
PENS
"sunfish" 1.0 0 -955883 true
"bass" 1.0 0 -5825686 true
"gar" 1.0 0 -16777216 true

MONITOR
965
15
1068
64
Algae  (kg/ha)
count algaes
3
1

SLIDER
116
11
458
44
sunlight
sunlight
0
8000
8000
100
1
kilocal/ha

MONITOR
1079
15
1177
64
Sunfish  (kg/ha) 
count sunfishes
3
1

SLIDER
114
51
323
84
initial-sunfish-biomass
initial-sunfish-biomass
0
500
200
5
1
kg/ha

SLIDER
466
11
863
44
initial-algae-biomass
initial-algae-biomass
0
15000
4000
10
1
kg/ha

SLIDER
332
52
525
85
initial-bass-biomass
initial-bass-biomass
0
100
20
1
1
kg/ha

MONITOR
1188
15
1282
64
Bass  (kg/ha)
count bass
3
1

SLIDER
532
52
708
85
initial-gar-biomass
initial-gar-biomass
0
15
0
1
1
kg/ha

MONITOR
1293
15
1385
64
Gar   (kg/ha)
count gar
3
1

SLIDER
715
51
864
84
hours-fishing
hours-fishing
0
5
1
1
1
hr/day

MONITOR
889
15
958
64
Days
tocks
3
1

MONITOR
25
547
238
596
Average bass catch (kg/day) over 1 yr
average-yield
1
1

PLOT
258
114
865
282
Producers
time (days)
biomass (kg/ha)
0.0
100.0
0.0
5000.0
true
true
PENS
"algae" 1.0 0 -10899396 true

PLOT
42
114
231
532
Biomass
species
biomass (kg/ha)
0.0
5.0
0.0
10000.0
true
true
PENS
"algae" 0.1 1 -10899396 true
"sunfish" 0.1 1 -955883 true
"bass" 0.1 1 -5825686 true
"gar" 0.1 1 -16777216 true

@#$#@#$#@
WHAT IS IT?
-----------
NetLogo-Population Dynamics introduces students to the concept of a carrying capacity by means of an open-ended problem, namely how to create the best bass fishing pond possible. To begin addressing this question, students are invited to consider a very simple pond ecosystem containing only algae, the producer in this system. Students will explore how the carrying capacity of the pond for algae is affected by available sunlight. Students then study the effects of predation and competition by systematically introducing sunfish (a predator on pondlife), bass (a predator on sunfish), and gar (a competitor with bass for sunfish). As a final activity, students explore the effect of fishing on the system. 

USING THE SIMULATION
-----------
1. Elements of the ecosystem are introduced by several sliders. Set sunlight to some value greater than 1000 and algae to some number greater than 0. Click on the light blue SETUP button to populate the pond with the chosen initial starting biomass value for algae. Click the light blue GO button to start the simulation. Clicking the GO button a second time stops the simulation.

2. The BIOMASS bar graph displays currrent information regarding the relative biomasses of all living organisms. Two line graphs chart fluctuations in the relative biomasses of PRODUCERS and CONSUMERS as they change over time. (Note that to faciliate study a smaller y-scale is used to measure consumer biomass because biomasses associated with producers (plants) are always much larger than that associated with consumers in any stable ecosystem.

3. One can think about the dynamics of this ecosystem in terms of energy flow as follows:

SUNLIGHT ==> ALGAE ==> SUNFISH ==> BASS ==> FISHING

The flow of energy through almost all ecosystems requires the conversion of radiant energy from the sun into chemical energy by plants (producers) through the process of photosysnthesis. The presence of plants makes it possible for other organisms that lack the capacity to directly use sunlight energy (aka consumers) to survive in this ecosystem. Herbivores get energy from plants; carnivores get energy from herbivores and other carnivoes. Transfer of energy between levels as well as the use of energy by organisms results in its conversion from one form (e.g. chemical energy) to another form (e.g. mechanical energy). Such transformations are never perfect, they always involve the loss of energy in the form of heat, which dissipates into the surrounding environment and ultimately outer space. In the NetLogo-Population Dynamics simulation. algae represent producers, sunfish represent herbivores, and bass, gar and fisherman all represent carnivores. 

The following step-wise appraach to this simulation can be cast as an attempt to figure out how to create the bess bass fishing pond possible. We know that a bass fishing pond will miniimally include sunlight, algae, sunfish, bass and the presence of fishermen. How do we determine which values will ensure the best bass fishing pond possible? We can figurre out how the elements of the bass pond are related to one another by systematically creating a series  of ever more complicated pond ecosystems, beginning with a very simple system composed of sunlight and algae.

A SIMPLE ECOSYSTEM: A POND COMPOSED OF ALGAE
-----------
Algae (green) is the producer for this ecosystem. The first stage in our inquiry is to figure out what relationship (if any) exists between algae and sunlight. To do this we will study the effects of two different independent variables (amount of sunlight, initial-algae-biomass) on two dependent variables, the carrying capacity of the system for algae, A(k), and the time it takes to reach this carrying capacity, A(kt).

1. Stop the simulation if you haven't already done so by clicking on the GO button.
2. Set the sunlight value to 4,000 kilocalories per hectare and the initial-algae-biomass slider to 10 kilograms per hectare. Make sure all other sliders are set to zero and click the SETUP button to introduce algae into the pond.
3. Click the GO button to start the simulation. Observe the growth of the algae over time in the PRODUCERS graph. 
4. After about 500 days, stop the simulation by clicking on the GO button once more. The curve depicted on the PRODUCERS graph is a classic example of a logorthmic growth curve. 

The carrying capacity for a species represents an upper limit on the total number of organisms representing that species that can coexist together in that ecosystem once the system stabilizes. It is important to think of carrying capacities as dynamic equilibrium, in which the number of births is roughly equal to the number of deaths. 
Thus, although the algae population continues to fluctuate over time, these fluctuations appear to converge upon a single biomass value, namely 6,200 kg/ha.This occurs after about 375 days.

At this point one can ask a series of "What if?" questions that represent separate experimnents, e.g. What if the sunlight value were higher (i.e. we considered a pond that was closer to the equator where it would receive more direct sunlight)? Will this affect the carrying capacity or the time it takes the system to reach it? Predict what you think will happen and then run the simulation using those values. Do at least three experimental runs and then analyze the results of your trials to see if you can detect any patterns. If you do, consider how an ecologist might explain the trend(s) you observe.

One can similarly ask what would happen if one chose a different initial-algae-biomass value to seed the pond. Predict what you think will happen and then run the simulation using those values. Do at least three experimental runs and then analyze the results of your trials to see if you can detect any patterns. If you do, consider how an ecologist might explain the trend(s) you observe.

A SLIGHTLY MORE COMPLICATED ECOSYSTEM: ADDDING SUNFISH
-----------
We can simulate the introduction of sunfish likewise by setting the initial-sunfish-biomass value to some number greater than zero. Again, try predicting what the effects of this introduction will be. It may be that the relationships previously observed between sunlight and initial-algae-biomass values on the carrying capacity and time it takes to reach the carrying capacity will no longer hold. We also want to consider what the effect of changing sunlight or the initial biomass values for algae and sunfish will be on the sunfish carrying capacity and the time it takes to reach its carrying capacity. For each of the independent variables (sunlight, initial-algae-biomass, initial-sunfish-biomass) conduct three experimental runs using different values. Measure the effects of each of these on the carrying capacities of the algae and sunfish, as well as the time it takes them to reach their carrying capacities. Do the patterns you observed in the simpler system still hold? Do you see any new patterns? Once more consider how an ecologist might explain your findings.


A MORE COMPLICATED ECOSYSTEM: ADDDING BASS
-----------
We can simulate the introduction of bass likewise by setting the initial-bass-biomass value to some number greater than zero. Again, try predicting what the effects of this introduction will be. It may be that the relationships previously observed between sunlight, initial-algae-biomass and initial-sunfish-biomass values on the carrying capacity and time it takes them to reach the carrying capacity will no longer hold. We also want to consider what the effect of changing sunlight or the initial biomass values for algae, sunfish and bass will be on the bass carrying capacity and the time it takes to reach its carrying capacity. For each of the independent variables (sunlight, initial-algae-biomass, initial-sunfish-biomass, initial-bass-biomass) conduct three experimental runs using different values. Measure the effects of each of these on the carrying capacities of the algae, sunfish and bass, as well as the time it takes them to reach their carrying capacities. Do the patterns you observed in the simpler system still hold? Do you see any new patterns? Once more consider how an ecologist might explain your findings.

AN EVEN MORE COMPLICATED ECOSYSTEM: ADDDING GAR
-----------
We can simulate competition in this ecosystem by adding gar, which like bass preys upon sunfish, by setting the initial-gar-biomass value to some number larger than zero. Predict what the effects of this introduction will be. Can bass and gar coexist over time in this system? Or does one go extinct? If the latter, is there some way (by changing the starting values for sunlight and initial-biomasses) to prevent this from happening? If you want to create the best bass fishing pond possible, what do these experiments tell you to do?

FINAL STEP: THE EFFECTS OF FISHING
-----------
The preceding steps will give students insight into how to maximize the bass population. As a final step we need to consider how much time per day the fisherman should fish on average to maximize his catch. After setting the other values to what you think will result in the largest bass population possible, shift the hours-fishing slider to one, two, three or four hours per day. Fishing begins on day 100 (after the system has stabilized), average yields are computed after one year on day 465. Is there a best amount of time the fisherman should fish to maximize his catch? If so, how might an ecologist explain this?

CREDITS AND REFERENCES
----------------------
This is based on elements from the several WolfSheep Predation NetLogo Programs by Uri Wilensky and was inspired by an earlier simulated ecosystem program called "Environmental Decision Making", originally developed as part of the BioQuest Library by Elizabeth C. Odum, H.T. Odum, and Niles S. Peterson.

RELATED MODELS
---------------
Look at "Rabbit Grass Weeds" and "Wolf Sheep Predation" for other models of interacting populations with different rules.

VERSION
-------
$Id$


@#$#@#$#@
default
true
0
Polygon -7500403 true true 150 5 40 250 150 205 260 250

link
true
0
Line -7500403 true 150 0 150 300

link direction
true
0
Line -7500403 true 150 150 30 225
Line -7500403 true 150 150 270 225

airplane
true
0
Polygon -7500403 true true 150 0 135 15 120 60 120 105 15 165 15 195 120 180 135 240 105 270 120 285 150 270 180 285 210 270 165 240 180 180 285 195 285 165 180 105 180 60 165 15

angler
false
0
Polygon -1 true false 89 163 95 190 236 191 266 159
Polygon -7500403 true true 154 113 168 114 175 137 170 163 152 162 147 140 148 125
Circle -7500403 true true 149 91 22
Line -7500403 true 174 132 228 83

arrow
true
0
Polygon -7500403 true true 150 0 0 150 105 150 105 293 195 293 195 150 300 150

bass
true
0
Polygon -5825686 true false 74 136 62 123 51 109 35 120 50 150 35 180 51 195 63 179 74 162
Polygon -5825686 true false 144 179 134 197 117 194 96 187 78 184 88 167
Polygon -5825686 true false 115 96 103 104 93 115 94 131 155 108 132 96
Polygon -2674135 true false 74 136 153 109 225 108 266 121 270 144 265 158 253 166 234 177 195 180 143 179 74 164
Circle -16777216 true false 214 118 30

box
false
0
Polygon -7500403 true true 150 285 285 225 285 75 150 135
Polygon -7500403 true true 150 135 15 75 150 15 285 75
Polygon -7500403 true true 15 75 15 225 150 285 150 135
Line -16777216 false 150 285 150 135
Line -16777216 false 150 135 15 75
Line -16777216 false 150 135 285 75

butterfly
true
0
Polygon -7500403 true true 150 165 209 199 225 225 225 255 195 270 165 255 150 240
Polygon -7500403 true true 150 165 89 198 75 225 75 255 105 270 135 255 150 240
Polygon -7500403 true true 139 148 100 105 55 90 25 90 10 105 10 135 25 180 40 195 85 194 139 163
Polygon -7500403 true true 162 150 200 105 245 90 275 90 290 105 290 135 275 180 260 195 215 195 162 165
Polygon -16777216 true false 150 255 135 225 120 150 135 120 150 105 165 120 180 150 165 225
Circle -16777216 true false 135 90 30
Line -16777216 false 150 105 195 60
Line -16777216 false 150 105 105 60

car
false
0
Polygon -7500403 true true 300 180 279 164 261 144 240 135 226 132 213 106 203 84 185 63 159 50 135 50 75 60 0 150 0 165 0 225 300 225 300 180
Circle -16777216 true false 180 180 90
Circle -16777216 true false 30 180 90
Polygon -16777216 true false 162 80 132 78 134 135 209 135 194 105 189 96 180 89
Circle -7500403 true true 47 195 58
Circle -7500403 true true 195 195 58

circle
false
0
Circle -7500403 true true 0 0 300

circle 2
false
0
Circle -7500403 true true 0 0 300
Circle -16777216 true false 30 30 240

cow
false
0
Polygon -7500403 true true 200 193 197 249 179 249 177 196 166 187 140 189 93 191 78 179 72 211 49 209 48 181 37 149 25 120 25 89 45 72 103 84 179 75 198 76 252 64 272 81 293 103 285 121 255 121 242 118 224 167
Polygon -7500403 true true 73 210 86 251 62 249 48 208
Polygon -7500403 true true 25 114 16 195 9 204 23 213 25 200 39 123

cylinder
false
0
Circle -7500403 true true 0 0 300

dot
false
0
Circle -7500403 true true 90 90 120

face happy
false
0
Circle -7500403 true true 8 8 285
Circle -16777216 true false 60 75 60
Circle -16777216 true false 180 75 60
Polygon -16777216 true false 150 255 90 239 62 213 47 191 67 179 90 203 109 218 150 225 192 218 210 203 227 181 251 194 236 217 212 240

face neutral
false
0
Circle -7500403 true true 8 7 285
Circle -16777216 true false 60 75 60
Circle -16777216 true false 180 75 60
Rectangle -16777216 true false 60 195 240 225

face sad
false
0
Circle -7500403 true true 8 8 285
Circle -16777216 true false 60 75 60
Circle -16777216 true false 180 75 60
Polygon -16777216 true false 150 168 90 184 62 210 47 232 67 244 90 220 109 205 150 198 192 205 210 220 227 242 251 229 236 206 212 183

fish 2
false
0
Polygon -1 true false 56 133 34 127 12 105 21 126 23 146 16 163 10 194 32 177 55 173
Polygon -7500403 true true 156 229 118 242 67 248 37 248 51 222 49 168
Polygon -7500403 true true 30 60 45 75 60 105 50 136 150 53 89 56
Polygon -7500403 true true 50 132 146 52 241 72 268 119 291 147 271 156 291 164 264 208 211 239 148 231 48 177
Circle -1 true false 237 116 30
Circle -16777216 true false 241 127 12
Polygon -1 true false 159 228 160 294 182 281 206 236
Polygon -7500403 true true 102 189 109 203
Polygon -1 true false 215 182 181 192 171 177 169 164 152 142 154 123 170 119 223 163
Line -16777216 false 240 77 162 71
Line -16777216 false 164 71 98 78
Line -16777216 false 96 79 62 105
Line -16777216 false 50 179 88 217
Line -16777216 false 88 217 149 230

flag
false
0
Rectangle -7500403 true true 60 15 75 300
Polygon -7500403 true true 90 150 270 90 90 30
Line -7500403 true 75 135 90 135
Line -7500403 true 75 45 90 45

flower
false
0
Polygon -10899396 true false 135 120 165 165 180 210 180 240 150 300 165 300 195 240 195 195 165 135
Circle -7500403 true true 85 132 38
Circle -7500403 true true 130 147 38
Circle -7500403 true true 192 85 38
Circle -7500403 true true 85 40 38
Circle -7500403 true true 177 40 38
Circle -7500403 true true 177 132 38
Circle -7500403 true true 70 85 38
Circle -7500403 true true 130 25 38
Circle -7500403 true true 96 51 108
Circle -16777216 true false 113 68 74
Polygon -10899396 true false 189 233 219 188 249 173 279 188 234 218
Polygon -10899396 true false 180 255 150 210 105 210 75 240 135 240

gar
true
0
Polygon -7500403 true true 136 193 128 216 116 222 92 217 81 206 80 187
Polygon -7500403 true true 37 130 23 116 8 122 0 142 0 161 2 178 17 195 33 186 36 155
Polygon -7500403 true true 37 128 92 116 196 112 271 121 295 153 286 166 294 172 271 181 206 197 155 196 33 187
Circle -1184463 true false 244 128 26
Circle -16777216 true false 248 135 14
Polygon -7500403 true true 139 114 129 89 120 86 98 87 83 94 86 118
Polygon -16777216 true false 192 117 171 118 162 126 158 148 160 165 168 175 188 183 211 186 217 185 206 181 172 171 164 156 166 133 174 121
Rectangle -1 true false 90 135 90 180
Rectangle -1 true false 120 135 120 180
Rectangle -1 true false 60 135 60 180
Rectangle -1 true false 150 135 150 180
Line -1 false 15 135 30 150
Line -1 false 15 165 30 165
Line -1 false 15 180 30 180
Rectangle -7500403 false true 60 135 75 180
Rectangle -7500403 true true 60 135 135 180
Rectangle -7500403 true true 15 150 30 165
Line -7500403 true 15 165 30 180
Rectangle -7500403 true true 15 165 30 180
Line -1 false 30 165 15 180

house
false
0
Rectangle -7500403 true true 45 120 255 285
Rectangle -16777216 true false 120 210 180 285
Polygon -7500403 true true 15 120 150 15 285 120
Line -16777216 false 30 120 270 120

leaf
false
0
Polygon -7500403 true true 150 210 135 195 120 210 60 210 30 195 60 180 60 165 15 135 30 120 15 105 40 104 45 90 60 90 90 105 105 120 120 120 105 60 120 60 135 30 150 15 165 30 180 60 195 60 180 120 195 120 210 105 240 90 255 90 263 104 285 105 270 120 285 135 240 165 240 180 270 195 240 210 180 210 165 195
Polygon -7500403 true true 135 195 135 240 120 255 105 255 105 285 135 285 165 240 165 195

line
true
0
Line -7500403 true 150 0 150 300

line half
true
0
Line -7500403 true 150 0 150 150

pentagon
false
0
Polygon -7500403 true true 150 15 15 120 60 285 240 285 285 120

person
false
0
Circle -7500403 true true 110 5 80
Polygon -7500403 true true 105 90 120 195 90 285 105 300 135 300 150 225 165 300 195 300 210 285 180 195 195 90
Rectangle -7500403 true true 127 79 172 94
Polygon -7500403 true true 195 90 240 150 225 180 165 105
Polygon -7500403 true true 105 90 60 150 75 180 135 105

plant
false
0
Rectangle -7500403 true true 135 90 165 300
Polygon -7500403 true true 135 255 90 210 45 195 75 255 135 285
Polygon -7500403 true true 165 255 210 210 255 195 225 255 165 285
Polygon -7500403 true true 135 180 90 135 45 120 75 180 135 210
Polygon -7500403 true true 165 180 165 210 225 180 255 120 210 135
Polygon -7500403 true true 135 105 90 60 45 45 75 105 135 135
Polygon -7500403 true true 165 105 165 135 225 105 255 45 210 60
Polygon -7500403 true true 135 90 120 45 150 15 180 45 165 90

pondlife
true
0
Circle -7500403 true true 138 132 26

sheep
false
0
Rectangle -16777216 true false 166 225 195 285
Rectangle -16777216 true false 62 225 90 285
Rectangle -7500403 true true 30 75 210 225
Circle -7500403 true true 135 75 150
Circle -16777216 true false 180 76 116

square
false
0
Rectangle -7500403 true true 30 30 270 270

square 2
false
0
Rectangle -7500403 true true 30 30 270 270
Rectangle -16777216 true false 60 60 240 240

star
false
0
Polygon -7500403 true true 151 1 185 108 298 108 207 175 242 282 151 216 59 282 94 175 3 108 116 108

sunfish
true
0
Polygon -1 true false 56 133 34 127 12 105 21 126 23 146 16 163 10 194 32 177 55 173
Polygon -7500403 true true 156 229 118 242 67 248 37 248 51 222 49 168
Polygon -7500403 true true 30 60 45 75 60 105 50 136 150 53 89 56
Polygon -7500403 true true 50 132 146 52 241 72 268 119 291 147 271 156 291 164 264 208 211 239 148 231 48 177
Circle -1 true false 237 116 30
Circle -16777216 true false 241 127 12
Polygon -1 true false 159 228 160 294 182 281 206 236
Polygon -7500403 true true 102 189 109 203
Polygon -1 true false 215 182 181 192 171 177 169 164 152 142 154 123 170 119 223 163
Line -16777216 false 240 77 162 71
Line -16777216 false 164 71 98 78
Line -16777216 false 96 79 62 105
Line -16777216 false 50 179 88 217
Line -16777216 false 88 217 149 230

target
false
0
Circle -7500403 true true 0 0 300
Circle -16777216 true false 30 30 240
Circle -7500403 true true 60 60 180
Circle -16777216 true false 90 90 120
Circle -7500403 true true 120 120 60

tree
false
0
Circle -7500403 true true 118 3 94
Rectangle -6459832 true false 120 195 180 300
Circle -7500403 true true 65 21 108
Circle -7500403 true true 116 41 127
Circle -7500403 true true 45 90 120
Circle -7500403 true true 104 74 152

triangle
false
0
Polygon -7500403 true true 150 30 15 255 285 255

triangle 2
false
0
Polygon -7500403 true true 150 30 15 255 285 255
Polygon -16777216 true false 151 99 225 223 75 224

truck
false
0
Rectangle -7500403 true true 4 45 195 187
Polygon -7500403 true true 296 193 296 150 259 134 244 104 208 104 207 194
Rectangle -1 true false 195 60 195 105
Polygon -16777216 true false 238 112 252 141 219 141 218 112
Circle -16777216 true false 234 174 42
Rectangle -7500403 true true 181 185 214 194
Circle -16777216 true false 144 174 42
Circle -16777216 true false 24 174 42
Circle -7500403 false true 24 174 42
Circle -7500403 false true 144 174 42
Circle -7500403 false true 234 174 42

turtle
true
0
Polygon -10899396 true false 215 204 240 233 246 254 228 266 215 252 193 210
Polygon -10899396 true false 195 90 225 75 245 75 260 89 269 108 261 124 240 105 225 105 210 105
Polygon -10899396 true false 105 90 75 75 55 75 40 89 31 108 39 124 60 105 75 105 90 105
Polygon -10899396 true false 132 85 134 64 107 51 108 17 150 2 192 18 192 52 169 65 172 87
Polygon -10899396 true false 85 204 60 233 54 254 72 266 85 252 107 210
Polygon -7500403 true true 119 75 179 75 209 101 224 135 220 225 175 261 128 261 81 224 74 135 88 99

wheel
false
0
Circle -7500403 true true 3 3 294
Circle -16777216 true false 30 30 240
Line -7500403 true 150 285 150 15
Line -7500403 true 15 150 285 150
Circle -7500403 true true 120 120 60
Line -7500403 true 216 40 79 269
Line -7500403 true 40 84 269 221
Line -7500403 true 40 216 269 79
Line -7500403 true 84 40 221 269

wolf
false
0
Rectangle -7500403 true true 195 106 285 150
Rectangle -7500403 true true 195 90 255 105
Polygon -7500403 true true 240 90 217 44 196 90
Polygon -16777216 true false 234 89 218 59 203 89
Rectangle -1 true false 240 93 252 105
Rectangle -16777216 true false 242 96 249 104
Rectangle -16777216 true false 241 125 285 139
Polygon -1 true false 285 125 277 138 269 125
Polygon -1 true false 269 140 262 125 256 140
Rectangle -7500403 true true 45 120 195 195
Rectangle -7500403 true true 45 114 185 120
Rectangle -7500403 true true 165 195 180 270
Rectangle -7500403 true true 60 195 75 270
Polygon -7500403 true true 45 105 15 30 15 75 45 150 60 120

x
false
0
Polygon -7500403 true true 270 75 225 30 30 225 75 270
Polygon -7500403 true true 30 75 75 30 270 225 225 270

@#$#@#$#@
NetLogo 3.1.4
@#$#@#$#@
setup
set grass? true
repeat 75 [ go ]
@#$#@#$#@
@#$#@#$#@
@#$#@#$#@