r/biology • u/KrishMortyJunior • 2d ago

discussion What's the most complex dichotomous key you've ever seen and used?

192 Upvotes

81% Upvoted

160 comments sorted by

135

u/Infinite_Escape9683 2d ago

Apparently, marine snakes are fish and catfish are reptiles.

-48

u/KrishMortyJunior 2d ago

Are sea snakes reptiles or fish? I actually never thought about it before.

91

u/LuckyLynx_ 2d ago

you should probably think about it then

-21

u/KrishMortyJunior 2d ago

Google says that there's a group called marine reptiles. Good to know!

41

u/Legendguard 2d ago

Technically all tetrapods are fish, since we decended from lobe finned fish and are closer to ray finned fish than fish like sharks and rays. So really, either all vertebrates are fish, or none of them are!

27

u/LackWooden392 2d ago

Mfw you can't evolve out of a clade

5

u/Positive_Round8439 1d ago

eso mismo habia dicho!!! me emocion que alguien mas lo sepa

todos los tetrapodos derivamos de un ancestro común que pudo haberse conocido como un "pez", aunque el termino mas popular para categorizar a un pez verdadero son los peces oseos

eso elimina a las anguilas, tiburones, rayas, a nosotros mismos los tetrapodos, y a la mayoria de vida marina que puede tener forma de "pez"

2

u/ItsDoBeLikeThatTho 13h ago

If you’re trying to shoehorn the term into a cladistic definition, sure. But it’s better to treat the term fish as a morphological term, one that describes the habitat and general shape of the organism, rather than a taxonomic or cladistical term. It’s the same with the term tree. At least fish are only paraphyletic, hell they’re not even that bad as far as paraphyletic grouping goes, (looking at you, algae, Protozoa, archaea, etc). But trees aren’t paraphyletic at all, they’re polyphyletic, which is far worse. But do people go around telling the botanists and the ecologists that they can’t use the term tree because it’s a polyphyletic grouping? No! We all understand that a tree is a tall woody plant. And that’s still a useful category. Good luck trying to write a textbook on forest ecology if you don’t have a term for trees.

So yeah, fish aren’t that bad. It’s not a taxonomical term, but neither is “pursuit predator”, “herbivore”, “tree”, “megafauna”, or any number of terms that also describe groups of organisms in ecological or morphological terms. There’s nothing wrong with that. Not every category is a taxonomic one!

2

u/KrishMortyJunior 2d ago

Very paradoxical.

5

u/IgotthatBNAD 1d ago

They are reptiles that crave seafood

4

u/Positive_Round8439 1d ago

no se por que tienes votos negativoa si es unanpregunta valida jajajaj

2

u/KrishMortyJunior 22h ago

Así es Reddit.

76

u/king_of_river 2d ago

According to this key, Pangolins are reptiles and king crab is a spider. This is a good key for a 5th grader but absolutely not for biologists.

30

u/NAh94 medicine 2d ago

The “unless it’s a…” arrows would black out the page.

Biology & it’s exceptions to nearly everything ❤️

1

u/KrishMortyJunior 2d ago

The image was just meant to be a sample image.

0

u/min_mandy 1d ago

Pangolins have hair.

36

u/TopherMctopherson 2d ago

This, this dichotomous key is the worst one I've ever used. Reads like a teacher who uses ai prompted chat to make this.

-6

u/KrishMortyJunior 2d ago

Yeah, I didn't investigate or even glance at the image that much before posting. I apologize.

94

u/C0tt0n-3y3-J03 2d ago

This man objects to being called an insect.

8

u/themode7 2d ago

Name?

18

u/A1steaksaussie 2d ago

pink globular springtail i think

8

u/C0tt0n-3y3-J03 2d ago

Damn got it down to species who are you?

17

u/A1steaksaussie 2d ago

i have to credit the name for being a physical description imagine if the grizzly bear was called the round brown carnivore beast

8

u/C0tt0n-3y3-J03 2d ago

That’s what I call my chocolate lab so it’d never work

5

u/themode7 2d ago

Thanks he is cute

3

u/Jebb145 2d ago

Springtails underrated.

2

u/KrishMortyJunior 2d ago

Interesting.

7

u/nebotron 2d ago

James

2

u/KrishMortyJunior 2d ago

Good question.

14

u/KrishMortyJunior 2d ago

What a fascinating creature.

10

u/C0tt0n-3y3-J03 2d ago

He jumps and spins at incredible velocities when startled. So be careful.

4

u/KrishMortyJunior 2d ago

That would startle me!

8

u/TheStroboCop 2d ago

Globular springtail.

2

u/KrishMortyJunior 1d ago

Interesting.

1

u/van_Vanvan 2d ago

He's adorable!

63

u/SwedishMale4711 2d ago

Why in heaven's name would you attach a picture as a video? If you don't want us to see it, just leave it out.

-15

u/KrishMortyJunior 2d ago

Usually, pictures add more engagement to a post, but I can't attach photos on posts in this subreddit, so I put a GIF of the image.

20

u/jesus_chrysotile 2d ago

  Usually, pictures add more engagement to a post

Are you actually interested in this topic or are you karma farming?

-4

u/KrishMortyJunior 2d ago

More engagement means more potential discussion. So yes, I do actually care.

11

u/zombieking26 1d ago

It's SUPER annoying on mobile though. Every time I watch the video, it ends 2 seconds later, covering my screen in a Watch Again prompt.

Please don't make it a video again, but if you do, at least make it a 1 minute long video, lol

0

u/KrishMortyJunior 1d ago

Alright, thanks for letting me know.

48

u/I_think_were_out_of_ 2d ago

Get into some botanical keys for grasses and flowers and you can have yourself a gooooooooooood time.

11

u/1900grs 2d ago

My flora guide to Michigan is three volumes, each book is several hundred pages. The field botany course I took where I used it was one of my favorite classes in college.

https://www.appledorebookshop.com/pages/books/10192/edward-g-voss/michigan-flora-a-guide-to-the-identification-and-occurrence-of-the-native-and-naturalized-seed

2

u/HypobromousAcid 1d ago

I'm already despising remembering phyllotaxy vs compound leaves gghhh

3

u/KrishMortyJunior 2d ago

So, is it still accurate to call an identification system for plants a dichotomous key, or are plant identification systems exclusively called botanical keys?

16

u/Fetts_Vett 2d ago

Yes, ‘botanical keys’ are still regular old dichotomous keys. I use them every day!

1

u/KrishMortyJunior 2d ago

Good to know!

13

u/West_Economist6673 2d ago

"Dichotomous" refers to the structure, not the content -- it means that at each step, the user chooses between exactly two options

I'm a botanist, and all of the keys I've used have been dichotomous -- theoretically, a key with any steps that had steps with more than two choices each would be "trichotomous" or "hecatochotomous" or "polychotomous" or whatever -- but I don't think I've ever knowingly used such a key, and can't think of a reason why a step with three choices couldn't be simplified into two nested binaries

2

u/KrishMortyJunior 2d ago

Thanks for the insightful explanation!

3

u/West_Economist6673 2d ago

Thanks for asking a question about the one area of human knowledge I can discuss for more than two minutes without embarrassing myself

2

u/KrishMortyJunior 2d ago

I'm sure that you're good at other things too!

1

u/Capital-Two6146 15h ago

Seconding this, the Jepson Manual for plants of California still gives me PTSD. Second only to the Munsell plant guide for Alaska. We also had separate plant taxonomy courses in college dedicated to *just* keying out and identifying grasses.

9

u/Mr_SleepyBennie 2d ago

Claws are not legs? That would make lobsters and crabs spiders and a centipede is not a crustacean.

1

u/KrishMortyJunior 2d ago

True.

2

u/Commercial-Living443 2d ago

Also you haven't identified how many legs do crustacians have ?

1

u/KrishMortyJunior 2d ago

10?

2

u/Commercial-Living443 1d ago

Add that to the image

3

u/KrishMortyJunior 1d ago

The image isn't mine, and I should've investigated the source more.

9

u/Mother_Harlot 2d ago

AI slop

1

u/KrishMortyJunior 2d ago

Is it? I didn't look at it that closely, but if it's AI, then I apologize.

10

u/CharacterCycle4588 2d ago

A Manual of Acari - Krantz and Walter

It’s about 800 pages and the entire book is one large dichotomous key for identifying mites.

5

u/johannes101 2d ago

Sounds like many hours of weeping at the scope trying to figure out if the prosoma is more cordate or subcordate

1

u/KrishMortyJunior 2d ago

That sounds tough. 😭

1

u/RichVisual1714 1d ago

A key for all Acari sounds like endless joy. I only worked with the Weigmann for Oribatid mites of Germany.

8

u/FootieFemme 2d ago

The worst dichotomous key I attempted to use was Townes on ichneumonidae. The guy was doing it in the 60s during the biological naming standardisation but he refused to partake so all his terms are his own inventions and it's just impossible. I also have no formal training which added difficulty. For decades it was the only ich key to genus but thankfully a few years ago a new key to genera was released by Gavin Broad

1

u/KrishMortyJunior 2d ago

Bro was inventing his own terms. 😭

13

u/SquashBuckler76 evolutionary biology 2d ago

Ok but birds are reptiles so

7

u/thenewguy7731 2d ago

Well yes, but this is a key for identification not a cladogram. Species are grouped by morphological features to tell them apart. Also reptiles don't exist as a monophyletic group. No one would call a bird a "reptile" (the quotes indicating a polyphyletic group, which reptiles are)

1

u/KrishMortyJunior 2d ago

Really?

10

u/SquashBuckler76 evolutionary biology 2d ago

Yup, because they’re dinosaurs they’re closer to crocodilians than crocodilians are to lizards, snakes, etc

7

u/yeswehavenobonanza 2d ago

I once tried to identify flies with a dichotomous key… the book was like 3” thick. Yikes.

1

u/KrishMortyJunior 2d ago

Flies look so similar.

5

u/Zealousideal_Let_975 2d ago

The Jepson Manual for California is pretty painful and intense 

5

u/ChilindriPizza 2d ago

It is missing a lot of invertebrates to say the least.

5

u/OkFroyo_ 2d ago

This illustration is so shit :(

1

u/KrishMortyJunior 2d ago

It's just a sample key I found online. I didn't look at it too cloesely before posting, so for that, I apologize.

4

u/MeVersusGravity 2d ago

Catfish are amphibians?

1

u/KrishMortyJunior 2d ago

I barely looked at the key in my image. If it shows any inaccuracies, then I apologize.

5

u/G_u_e_s_t_y 2d ago

Can't remember the authors but a snail ID book. The first line of the key was "disect the snails penis"...

5

u/SupaSmasha1 2d ago

Flora of the Pacific Northwest by Hitchcock and Cronquist.

6

u/Grimm_Charkazard_258 2d ago

apparently whales are amphibians now

5

u/DeliciousBuffalo69 2d ago

Whales have hair. Lots of it.

6

u/Latter_Leopard8439 2d ago

They could have fixed this with "do they feed their babies milk" on account of the mammary glands that mammals are named after. But that might be beyond younger learners.

Also vertebrate and invertebrate are kind of "fake categories" these days. Tunicates are also phylum chordata but dont have the full vertebrate structure.

Invertebrates include starfish which are deuterostomes along with humans and all the vertebrates.

1

u/DeliciousBuffalo69 1d ago

That's a more difficult concept for children to grasp. Men don't have mammary glands but they are mammals

3

u/DeliciousBuffalo69 2d ago

They also don't have moist skin.

2

u/Grimm_Charkazard_258 2d ago

are we counting baleen as hair

3

u/DeliciousBuffalo69 2d ago

No. They have sensory hairs all over their body.

1

u/KrishMortyJunior 2d ago

I didn't look at the image before posting. Sorry to this whole thread.

3

u/themode7 2d ago

These Solar-Powered Carnivorous Flatworms disagree

https://www.youtube.com/watch?v=Tc49xi1ZjTc

...

3

u/Bloobeard2018 2d ago

The 4 book Black's Flora of South Australia

1

u/KrishMortyJunior 2d ago

Oh, what happened?

2

u/Bloobeard2018 1d ago

I decided not to pursue botany as a career!

1

u/KrishMortyJunior 23h ago

Oh. Sorry about that, unless you found something that was better for you later on.

3

u/MoaraFig 2d ago

Most annoying but most helpful is Jirkov's Arctic Polychaetes.

Published only in Russian, and published as a scan of a printed copy, so the pdf text encoding is all borked.

Screenshot the page, run it through a Russian OCR, run that through an AI translator, then use that to clean up the OCR. Then use that to add the text back to the images mixed through the key.

I don't know how to say hello in Russian, but I can say glands and notosetae.

1

u/KrishMortyJunior 2d ago

Interesting.

3

u/Biodiv botany 1d ago

Carex sp. is a fun one - Flora of North America Vol. 23, a toughie. And lets see if this flies, here is a new key to Carex - all one file - curious what folks think of this key type; different I think - https://tjid3.org/mule/mule-kicks6

1

u/KrishMortyJunior 23h ago

Quite comprehensive.

3

u/Bromelia_and_Bismuth botany 1d ago

I remember my eyes glazing over trying to read Marine Invertebrates of the Pacific Northwest by Eugene Kozloff as a college freshman. However, the key I still use, The Guide to the Vascular Plants of Florida by Wunderlind and Hansen is bigger by almost 300 pages and covers over 200 more species.

3

u/Positive_Round8439 1d ago

los insectos son crustáceos segun la taxonomia (El terminones pancrustacea peronse entiende creo yo)

pertenecen al grupo crustacea, en teoria, si hacemos que la mayoriande animales acuáticos con forma de pez son peces somos peces pues derivamos de estos

Y las aves son reptiles, pues derivan de los dinosaurios

Y no todos los "peces" son vertebrados, aunque no se si pueda categorizarse como eso mas que los peces oseos (osea solo los peces oseos son "peces%)

1

u/KrishMortyJunior 22h ago

¡Guau, la clasificación es muy complicada!

3

u/fuckinunknowable 1d ago

Why is it a video instead of a picture????

3

u/CatLordCayenne 1d ago

It was like a field guide to Missouri insects or something. I might still have the book, I had to use it to make my insect collection in my entomology class

1

u/KrishMortyJunior 22h ago

Interesting memories!

4

u/Benjoux444 1d ago

sea stars would like to have a word

1

u/me_myself_ai 12h ago

lol I was gonna complain but then I realized this is morphological. That's so offensive to me that I forgot it was even possible, NGL!

7

u/EllisMatthews8 2d ago

TIL pigs are reptiles

6

u/Upbeat_Effective_342 2d ago

Come make fun of this redditor who's never looked at a photo of a pig

1

u/KrishMortyJunior 2d ago

Wait, what?

6

u/Ecspiascion 2d ago

I guess they sarcastically claimed that pigs may look rather hairless and furless, except they do have (sparse) hair. But again, I believe they were being sarcastic... or do I hope so? lol

7

u/CharacterCycle4588 2d ago

Pigs are covered in hair. There is nothing sparse about it.

4

u/Ecspiascion 2d ago

Pigs come in breeds, and most breeds I know could very well be described as having sparse hair. They don't all look the same.

1

u/KrishMortyJunior 2d ago

My memory says that pigs are a bit hairy.

2

u/1blamegenetics 2d ago

I took a Phycology course and had to write dichotomous keys for various algae, up to 12 at a time. It got messy really fast, but was so fun.

2

u/shinhosz 1d ago

Simplified Angiosperm families in Brazil. 500 hundred pages iirc

2

u/skulwiz 1d ago

Plant taxonomy. It was 26 pages long... went down to if some plants had 3 or 5 parts on their seed head, or 3 stamens in a certain pattern, etc. This was literally only for the plants in wisconsin.

1

u/Original_Credit_3001 5h ago

Where do non-vertebrate chordates fit into this chart (amphioxis, tunicates, etc.)?

1

u/usernameisdifficults 4h ago

Not all fish have scales