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==Explanation==
 
==Explanation==
This comic shows the total weight of {{w|Human|mankind}} and all other land {{w|mammals}}. Only a few centuries ago, {{w|humans}}, their {{w|pets}} and {{w|livestock}} came to make up a great proportion of the earth's land mammal {{w|biomass}}. Note that only land-dwelling mammals are taken into account, so for instance {{w|whales}} and {{w|sea cows}} will not be included. (Whether this only covers animals that cannot live on land or any {{w|marine mammals}} like for instance {{w|Pinniped|seals}} and {{w|walrus}}, is not clear).
+
{{incomplete|The division of animal blocks are clear but only 6 are labeled. Some qualified guesses as to how the other (at least the largest) blocks are divided should be possible... What about the layout of the blocks?}}
  
The design of the blocks loosely resembles a {{w|Cell (biology)|cell}}. This could be a reference to how these animals support humans, analogous to a cell supporting a central nucleus. If so, it seems that all the animals in this diagram, {{w|wild animals|wild}} or {{w|Domestication|domestic}}, in some way support human activity.
+
This comic is a [[Nerd Sniping]] by [[Randall]] to his viewers. This explain tries to figure out the missing parts.
  
The title text states that {{w|bacteria}} outweigh us thousands to one, without counting the several pounds of {{w|Human microbiota|bacteria in our body}} that are considered part of our own weight (like {{w|Gut flora}}). The aforementioned cell could also be a bacterium, making it a possible reference to the title text, since 1256 blocks have been used to sketch the "cell", and bacteria outweigh us by about this factor.
+
The comic shows the total weight of mankind and all other land mammals.  
 +
Only a few centuries ago humans, and their pets and livestock, come to occupy such a great proportion of the earth's land mammal mass.
  
This comic may be a [[Nerd Sniping|nerd snipe]] from [[Randall]], challenging his readers to figure out the missing parts.
+
Per the diagram, there are 358 million tons of humans, 864 million tons of pets and livestock, of which 520 million tons comes from cattle, and 34 million tons of wild animals; for a total of 1.3 billion tons.
  
Randall also discusses animal biomass in [http://whatif.xkcd.com/123/ Fairy Demographics] in which he compares the biomass of "fairies" to humans, horses, and humpback whales.
+
As of March 2014, the world population was about 7.16 billion people<sup>[https://www.census.gov/popclock/ 1]</sup> and so the comic assumes an ''average human'' weighs 50 kg: 7.16 billion people &times; 50 kg = 358 billion kg = 358 million tons. The BMC Public Health 2012 (12:439) article "[http://www.biomedcentral.com/content/pdf/1471-2458-12-439.pdf The weight of nations: an estimation of adult human biomass]" estimated the average ''adult'' weighed 52.0 kg ([http://www.biomedcentral.com/content/pdf/1471-2458-12-439.pdf#page=3 Table 3]), but the authors  noted that their work "did not estimate the bio-mass in children who comprise a significant proportion of the population in many countries".  The 50 kg estimate in this comic includes the 25% or more of the [http://www.worldometers.info/world-population/world-population-gender-age.php worlds population below 15 years of age] making the 2 kg reduction a credible adjustment.
  
===Weight===
+
Cattle, in aggregate, are much heavier than the human population, but we do manage to outweigh both sheep and pigs - which may come as a surprise - as these animals probably by far outweigh the population in the countries that produce the main part of the worlds meat from such animals.
According to the diagram, there are 358 million tons of humans, 864 million tons of pets and livestock, of which 520 million tons comes from {{w|cattle}}, and 34 million tons of wild animals; for a total of 1.256 billion tons.
 
The number of blocks represents the weight of the group in millions of tons = billions of kg. Note that some entries have the same number of blocks, and thus have the same rank.
 
  
====Humans====
+
It is interesting to note that the world's heaviest land dwelling animal - the elephant - only takes up one square! It is the only type of wild animal to be singled out in the comic.
Cattle, in aggregate, are much heavier than the human population. Humans outweigh both {{w|sheep}} and {{w|Domestic pig|pigs}} put together. This may be a surprise for people in the countries that produce the majority of meat from such animals, because here these animals outweigh the population. But there are many parts of the world where especially pigs are not eaten, and it is not every where that sheep is in great demand. And especially in the some of the most populations dense regions in the {{w|Third World}} meat is not something you can afford to eat on a regular basis.
 
  
====Our pets and livestock====
+
There are 8 distinct blocks of wild animal (elephants and 7 others). There are 13 distinct blocks of pets and live stock (only the top 5 are labeled - in order of weight they are: Cattle, Sheep, Pigs, Goats and Horses). Dogs would properly also take up a large part - but how detailed are the division of species...? 
There are 13 distinct blocks of pets and live stock; only the top 5 are labeled - in order of weight they are: Cattle, Sheep, Pigs, {{w|Goats}} and {{w|Horses}}. Cattle, in aggregate, are much heavier than the human population, which has been inserted in the table for comparison:
+
 
 +
{{W|Water buffalo|Water buffalos}} seem to be missing completely.  According to Wikipedia, there are {{W|List of even-toed ungulates by population|172 million}} of them with a weight of 300 - 550 kg each.  With an average between 300-400 kg (depending on the number of calves) there is 50-70 million tons of them - giving them a much larger weight than goats, which would put them in fifth place in the table below.
 +
 
 +
The comic references the book [http://vaclavsmil.com/the-earths-biosphere-evolution-dynamics-and-change/ The Earth's Biosphere: Evolution, Dynamics, and Change] by {{W|Vaclav Smil}} as the source for most of the data - although a few other sources has also been used. These other sources are not referenced.
 +
 
 +
Note that only land dwelling mammals are taken into account - thus no whales. It is not clear as to where, for instance, seals, sea lions and walruses belong -  although they could belong to land mammals as they spend a lot of time on land - as opposed to whales.
 +
 
 +
All other types of animals are not included. For instance, the weight of insects would outweigh us by far. Although not as much as the bacteria mentioned in the title text - they outweigh us thousands to one.
 +
 
 +
And that is without counting the part of our body weight that consist of bacteria: Several pounds. A fact that most people would properly like to ignore - which is a good reason to mention it here. These pounds are already counted as part of the total human weight.
 +
 
 +
There has been some speculation about the design of the blocks. They could be seen as resembling a cell (a bacteria). An extra joke in this could be that a little more than thousand blocks representing mammal weight has been used to sketch this bacteria and bacteria's outweighs the mammals on this order.
 +
 
 +
==Table of the block sizes==
 +
 
 +
*The table below ranks each group of blocks from 1 to 22 according to the size of the group = the number of blocks. The number of blocks represents the weight of the group in millions of tons = billions of kg.
 +
*The comic contains a total of 1256 blocks in three colors representing the 1.256 billion tons of land dwelling mammals.
 +
**358 million tons from humans - dark grey color
 +
**864 million tons from mammalian pets and livestock - light grey color
 +
**34 million tons of wild land dwelling mammals - green color
 +
 
 +
:Feel free to enter a comment on the groups especially those that are not already identified.
 +
 
 +
:The population should only be be stated (in millions) if it can found through references - the XKCD average weight (in kg) is then given from the number of blocks in the group.
 
{| class="wikitable sortable" style="width: auto; text-align: center; font-size: 95%; table-layout: fixed; line-height:1.25"
 
{| class="wikitable sortable" style="width: auto; text-align: center; font-size: 95%; table-layout: fixed; line-height:1.25"
 
|-
 
|-
! Total&nbsp;Rank
+
! Rank
! Weight&nbsp; (Millions of tons)
+
! #&nbsp;Blocks
! Name
+
! Type
 +
! Text
 +
!Population (millions)
 +
!Weight (kg)
 +
!Notes/comments
 
|-
 
|-
| {{sort|00001|1}}
+
| 1
| {{sort|00520|520}}
+
| 520
|  Cattle
+
| Pets/Livestock
 +
| Cattle
 +
| 1000
 +
| 520
 +
| They only outweighs us by weight - not by numbers - there has been a stable [http://www.statista.com/statistics/263979/global-cattle-population-since-1990/ population] of about {{W|List of even-toed ungulates by population|1 billion cattle}} since 2007.
 
|-
 
|-
| {{sort|00001|2}}
+
| 2
| {{sort|00358|358}}
+
| 358
| (Humans)
+
| Humans
 +
|  
 +
| 7152
 +
| 50.1
 +
| According to the U.S. Census Bureau's [http://www.census.gov/popclock/ population counter], there were 7.1516 billion people in the world as of March 4, 2014.
 
|-
 
|-
| {{sort|00003|3}}
+
| 3
| {{sort|00135|135}}
+
| 135
 +
| Pets/Livestock
 
| Sheep
 
| Sheep
 +
| 1000
 +
| 135
 +
|There are about {{W|List of even-toed ungulates by population|1 billion sheep}} according to Wikipedia. The {{W|Domestic_sheep#Description_and_evolution|average sheep}} weight of 135 kg seems highly exaggerated as only the rams can weigh more then that.
 
|-
 
|-
| {{sort|00004|4}}
+
| 4
| {{sort|00090|90}}
+
| 90
 +
| Pets/Livestock
 
| Pigs
 
| Pigs
 +
| 1000/2100?
 +
| 90/43?
 +
| According to Wikipedia, the {{W|Pig#Distribution_and_evolution|population of pigs}} is about {{W|List of even-toed ungulates by population|1 billion}}. According to the [http://apps.fas.usda.gov/psdonline/psdReport.aspx?hidReportRetrievalName=Swine+Summary+Selected+Countries&hidReportRetrievalID=1649&hidReportRetrievalTemplateID=7 2nd reference] given for this in the wiki article, there is, however, 1.3 billions, and then 0.8 billion more (probably piglets) for a total of 2.1 billion? The piglets will not weigh much though.
 
|-
 
|-
| {{sort|00005|5}}
+
| 5
| {{sort|00039|39}}
+
| 39
 +
| Pets/Livestock
 
| Goats
 
| Goats
 +
| 864
 +
| 45
 +
| The goat population can be summed to 864 million from {{W|Goat#Worldwide_goat_population_statistics|Wikipedia's goat article}}. According to this list there are {{W|List of even-toed ungulates by population|850 million goats}}.
 
|-
 
|-
| {{sort|00006|6}}
+
| 6
| {{sort|00029|29}}
+
| 29
 +
| Pets/Livestock
 
| Horses
 
| Horses
 +
| 58
 +
| 500
 +
| According to Wikipedia there is a population of {{W|List of odd-toed ungulates by population|58 million}} horses. Horses can {{W|Horse#Size_and_measurement|weigh from 400-1000 kg}}. There are probably not that many foals compared to adults, as for instance for cattle and pigs.
 
|-
 
|-
| {{sort|00007|7}}
+
| 7
| {{sort|00013|13}}
+
| 13
| Unlabeled
+
| Pets/Livestock
|-
 
| {{sort|00009|9}}
 
| {{sort|00008|8}}
 
| Unlabeled
 
|-
 
| {{sort|00010|10}}
 
| {{sort|00007|7}}
 
| Unlabeled
 
|-
 
| {{sort|00010|10}}
 
| {{sort|00007|7}}
 
| Unlabeled
 
|-
 
| {{sort|00013|13}}
 
| {{sort|00006|6}}
 
| Unlabeled
 
|-
 
| {{sort|00014|14}}
 
| {{sort|00005|5}}
 
| Unlabeled
 
|-
 
| {{sort|00017|17}}
 
| {{sort|00003|3}}
 
| Unlabeled
 
|-
 
| {{sort|00019|19}}
 
| {{sort|00002|2}}
 
| Unlabeled
 
|-
 
|}
 
 
 
====Wild Animals====
 
There are 8 distinct blocks of wild animal ({{w|elephants}} and 7 others). The elephant is the only type of wild animal to be singled out in the comic. This may possibly be due to elephants being the largest land mammal. And yes, the world's heaviest land animal only takes up one square. Also interesting is that the largest group of wild animals only comes in on the 8th place in the ranking (which is shared between the two tables).
 
{| class="wikitable sortable" style="width: auto; text-align: center; font-size: 95%; table-layout: fixed; line-height:1.25"
 
|-
 
! Rank
 
! Weight&nbsp; (Millions of tons)
 
! Name
 
|-
 
| {{sort|00008|8}}
 
| {{sort|00010|10}}
 
| Unlabeled
 
|-
 
| {{sort|00010|10}}
 
| {{sort|00007|7}}
 
| Unlabeled
 
|-
 
| {{sort|00014|14}}
 
| {{sort|00005|5}}
 
| Unlabeled
 
|-
 
| {{sort|00016|16}}
 
| {{sort|00004|4}}
 
| Unlabeled
 
|-
 
| {{sort|00017|17}}
 
| {{sort|00003|3}}
 
| Unlabeled
 
|-
 
| {{sort|00019|19}}
 
| {{sort|00002|2}}
 
| Unlabeled
 
|-
 
| {{sort|00019|19}}
 
| {{sort|00002|2}}
 
| Unlabeled
 
|-
 
| {{sort|00022|22}}
 
| {{sort|00001|1}}
 
| Elephants
 
|-
 
|}
 
 
 
====References====
 
The comic references the book ''[https://www.amazon.com/exec/obidos/ASIN/0262692988/vaclavsmil-20/ The Earth's Biosphere: Evolution, Dynamics, and Change]'' by {{W|Vaclav Smil}} as the source for most of the data. A few other sources have also been used, but were not referenced.
 
On page 186 of Smil's book, there is a bar chart with the following values:
 
{| class="wikitable sortable" style="width: auto; text-align: center; font-size: 95%; table-layout: fixed; line-height:1.25"
 
|-
 
! (Millions of tons)
 
! Name
 
|-
 
| {{sort|00008|0.8}}
 
| Elephants
 
|-
 
| {{sort|00400|40}}
 
| Horses
 
|-
 
| {{sort|01000|100}}
 
| Pigs
 
|-
 
| {{sort|04500|450}}
 
| Cattle
 
|-
 
| {{sort|02800|280}}
 
|  People
 
|-
 
| {{sort|00800|80}}
 
|  Whales
 
|-
 
| {{sort|00300|30}}
 
| all&nbsp;wild&nbsp;{{w|vertebrates}}
 
|-
 
| {{sort|06500|650}}
 
| all&nbsp;domesticated&nbsp;vertebrates
 
|-
 
|}
 
Note that all labelled non-human animals are in this table. It seems that this table was the source of most of the data in the comic.  Only land dwelling mammals are taken into account. Whales, wild vertebrates, and domesticated vertebrates are not included in the comic.
 
 
 
====Unlabeled Animals====
 
These are guesses about the identity of the unlabeled animals
 
{| class="wikitable" style="width: auto; text-align: center; font-size: 95%; table-layout: fixed; line-height:1.25"
 
|-
 
! Rank
 
! Comic weight (Millions of tons)
 
! Type
 
! Guess
 
! Actual Population (Millions)
 
! Average Weight (kg)
 
! Total weight (Millions of kg)
 
! Explanation
 
|-
 
| rowspan="1" |7
 
| rowspan="1" |13
 
| rowspan="1" |Pets/Livestock
 
 
|  
 
|  
|
 
 
|
 
|
 
|
 
|
 
|
 
|
 
|-
 
|-
| rowspan="1" |8
+
| 8
| rowspan="1" |10
+
| 10
| rowspan="1" |Wild animals
+
| Wild animals
 
|  
 
|  
 
|
 
|
 
|
 
|
|
+
| The largest grouping of wild animals, less than 1/50 of the weight of cattle - although representing almost a third of all the wild land mammals.
|
 
 
|-
 
|-
| rowspan="1" |9
+
| 9
| rowspan="1" |8
+
| 8
| rowspan="1" |Pets/Livestock
+
| Pets/Livestock
 
|  
 
|  
|
 
 
|
 
|
 
|
 
|
 
|
 
|
 
|-
 
|-
| rowspan="2" |10
+
| T10
| rowspan="2" |7
+
| 7
| rowspan="2" |Pets/Livestock
+
| Pets/Livestock
| {{w|Camel}}
+
| Camel?
| 17
+
|17
| 412
+
|412
| 7004
+
|Wikipedia lists 17M as the number of camels. An average based on wikipedia numbers for male and female is about 500kg. So including the non-adult camels an average around 400 kg seems as a realistic estimate.
| Wikipedia lists the number of camels as 17 million. An average weight, based on Wikipedia's numbers for male and female, is about 500&nbsp;kg. So, including the non-adult camels, an average around 400&nbsp;kg seems to be a realistic estimate.
 
 
|-
 
|-
| &nbsp;
+
| T10
|
+
| 7
|
+
| Pets/Livestock
|
 
|
 
|-
 
| rowspan="1" |10
 
| rowspan="1" |7
 
| rowspan="1" |Pets/Livestock
 
 
|  
 
|  
 
|
 
|
|
 
 
|
 
|
 
|
 
|
 
|-
 
|-
| rowspan="1" |10
+
| T10
| rowspan="1" |7
+
| 7
| rowspan="1" |Wild animals
+
| Wild animals
|
 
 
|  
 
|  
 
|
 
|
Line 241: Line 154:
 
|
 
|
 
|-
 
|-
| rowspan="2" |13
+
| 13
| rowspan="2" |6
+
| 6
| rowspan="2" |Pets/Livestock
+
| Pets/Livestock
| {{w|Dogs}}
+
| Dogs?
 
| 400
 
| 400
 
| 15
 
| 15
| 6000
+
|According to Wikipedia, there are 400M dogs worldwide. Assuming an average size at 15kg, gives 6 blocks. Small dog=2&nbsp;kg large dog = 100&nbsp;kg the log average is about 15&nbsp;kg. 
|According to Wikipedia, there are 400 million dogs worldwide. If the average weight is 15&nbsp;kg, there would be 6 blocks.<!-- Small dog=2 kg large dog = 100 kg the log average is about 15 kg. -->
 
|-
 
| &nbsp;
 
|
 
|
 
|
 
|
 
 
|-
 
|-
| rowspan="2" |14
+
| T14
| rowspan="2" |5
+
| 5
| rowspan="2" |Pets/Livestock
+
| Pets/Livestock
| {{w|Donkeys}}
+
| Donkeys?
 
| 41
 
| 41
 
| 122
 
| 122
| 5002
+
| There are roughly 41 Million {{w|Donkey#Present status|donkeys}} on earth and the average weight is about 125&nbsp;kg  
| There are roughly 41 million {{w|Donkey#Present status|donkeys on Earth}}, with an average weight of about 125&nbsp;kg.
 
 
|-
 
|-
| &nbsp;
+
| T14
|  
+
| 5
 +
| Wild animals
 
|  
 
|  
|
 
|
 
|-
 
| rowspan="1" |14
 
| rowspan="1" |5
 
| rowspan="1" |Wild animals
 
|
 
|
 
 
|
 
|
 
|
 
|
 
|
 
|
 
|-
 
|-
| rowspan="1" |16
+
| 16
| rowspan="1" |4
+
| 4
| rowspan="1" |Wild animals
+
| Wild animals
 
|  
 
|  
|
 
 
|
 
|
 
|
 
|
 
|
 
|
 
|-
 
|-
| rowspan="1" |17
+
| T17
| rowspan="1" |3
+
| 3
| rowspan="1" |Pets/Livestock
+
| Pets/Livestock
 
|  
 
|  
|
 
 
|
 
|
 
|
 
|
 
|
 
|
 
|-
 
|-
| rowspan="1" |17
+
| T17
| rowspan="1" |3
+
| 3
| rowspan="1" |Wild animals
+
| Wild animals
 
|  
 
|  
|
 
 
|
 
|
 
|
 
|
 
|
 
|
 
|-
 
|-
| rowspan="2" |19
+
| T19
| rowspan="2" |2
+
| 2
| rowspan="2" |Pets/Livestock
+
| Pets/Livestock
| {{w|Cats}}
+
| Cats?
| 500
+
|500
| 4
+
|4
| 2000
+
|Wikipedia quotes 500M domestic cats worldwide, with an average weight of 4.5&nbsp;kg. So with kittens 4 kg may seem very realistic.
| There are 500 million domestic cats worldwide. The average weight of an adult cats is 4.5&nbsp;kg. Factoring in the lighter weight of immature cats, 4&nbsp;kg as an average for all cats, (adult and immature) is within the range of possibility. (According to [[526: Converting to Metric]] cats do weigh 4 kg, only with caption do they reach 4.1 kg).
 
 
|-
 
|-
| &nbsp;
+
| T19
|
+
| 2
|
+
| Wild animals
|
 
|
 
|-
 
| rowspan="1" |19
 
| rowspan="1" |2
 
| rowspan="1" |Wild animals
 
 
|  
 
|  
|
 
 
|
 
|
 
|
 
|
 
|
 
|
 
|-
 
|-
| rowspan="2" |19
+
| T19
| rowspan="2" |2
+
| 2
| rowspan="2" |Wild animals
+
| Wild animals
| {{W|Rat#Species and description|Rat}}
+
| Rats
| 4000
+
|4000
| 0.5
+
| 500
| 2000
+
|A rat in the wild {{W|Rat#Species_and_description|seldom weigh over 500 g}}. {{W|World Health Organization|WHO}} estimate of 4 Billion rats (citation needed) and a comparable number of mice (The {{W|House_mouse#Characteristics|House mouse}} weighs only about 20 g and mice would thus only fill 0.08 block).
|The {{W|World Health Organization}} estimates 4 billion rats{{Actual citation needed}} worldwide. The average weight of an adult rat is under 500 g.  
 
 
|-
 
|-
| &nbsp;
+
| 22
|  
+
| 1
|  
+
| Wild animals
|
+
| Elephants
|
+
| 0.75
 +
| 1300
 +
| The only wild animal to be singled out with text - also the heaviest land dwelling animal - but still only take up one block. According to Wikipedia the wild poulation of the {{W|African elephant}} is around 700,000 (decreased from 1.3 mill in the 90s). For the {{W|Asian elephant}} it is as low as 40-50,000. For a total of 750,000 individuals. Any animals in the zoo or domesticated Asian elephants should not be counted. As adult African female elephants (who is probably the most abundant) weigh 2-3 ton, 1.3 ton seems a little low, especially since their is not a lot of calves as the elephants have a long lifespan. However, even with an average weight of 2 ton, the total weight would only be 1.5 million ton, and could be rounded down to 1 block...
 
|-
 
|-
 
|}
 
|}
  
 
==Transcript==
 
==Transcript==
:[Caption at the top of this chart:]
+
:'''Earth's LAND MAMMALS by weight'''
:<big>'''Earth's <big><big>Land Mammals</big></big> by Weight'''</big>
 
  
:[Below the caption is a light gray block with a label (in light gray as well) to indicating the value of each block:]  
+
:[A block indicating the value of each block:] = 1,000,000 tons
:<font color="gray">= 1,000,000 tons</font>
 
  
:[Below this there is a row with three blocks each in a different color, dark and light gray and green, each block is labeled to the right:]  
+
:[Dark gray block:] Humans
:'''Humans'''
+
:[Light gray block:] Our pets and livestock
:'''Our pets and livestock'''
+
:[Green block:] Wild animals
:'''Wild animals'''
 
  
:[The rest of the comic consist of a chart with different groups made up of these individually and differently colored blocks, each grouping representing the weight of a different mammals, except the center part, the only one with dark gray block, which represent humans. The largest group to the left is the only one larger than the humans group in the center. There are 22 groups in total, 1 human group with 358 dark gray block, 13 groups of light gray with a total of 864 blocks and 8 green groups with a total of 34 blocks for a total of 256 blocks. Both the light gray and the green groups are spread out on all sides of the human center group. Only difference is that all the green are on the very outside, whereas some of the smaller light gray groups are close to the core, far from the outside. The five largest groups of light gray blocks are labeled, as well as the smallest group consisting only of a single green block. All the labels has a line pointing to the relevant group and all of them are on the outside of the entire block. Going clockwise from the top left the labels are:]
+
:[The rest of the comic consist of blocks representing the weight of mammals. Some of the blocks are labeled:]
:<big><font color="gray">Cattle</font></big>
+
:*Cattle
:<big><font color="gray">Pigs</font></big>
+
:*Pigs
:<big><font color="gray">Goats</font></big>
+
:*Goats
:<big><font color="gray">Sheep</font></big>
+
:*Sheep
:<big><font color="gray">Horses</font></big>
+
:*Elephants
:<big><font color="gray">Elephants</font></big>
+
:*Horses
  
:[At the bottom right of the comic is the following gray text with a reference:]
+
:Data from Vaclav Smil's ''The Earth's Biosphere: Evolution, Dynamics, and Change'', plus a few other sources.
:<font color="gray">Data from Vaclav Smil's ''The Earth's Biosphere: Evolution, Dynamics, and Change'', plus a few other sources.</font>
 
  
 
{{comic discussion}}
 
{{comic discussion}}
 
[[Category:Charts]]
 
[[Category:Animals]]
 

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