musculo vivicare

my blog is a safe space for me. the rest of you are in danger i think

i’ve got Men at Arms open on Clara and Raven Stratagem open on my phone, which is a great combo to make a guy constantly pick up the wrong ebook device and go “what the fuck is HAPPENING”

I’m remembering why I never actually read most of the Discworld novels ... I have read SOME of Discworld, but not very much of it. as a child I read The Wee Free Men (charming, I love Tiffany), part of Eric (as a ten-year-old fan of Bartimaeus I was enticed by the description of demon deals and then thoroughly put off by Rincewind), and one of the city books, I don’t remember which one, possibly Feet of Clay, I’ll remember when I reread it probably. which is like juuuust barely enough Discworld to mostly grok the references. but I didn’t read any others. I got them all off Humblebundle for a steal recently and thought I’d try again, since I’ve been on a bit of a comfort read kick these last few months. I gave Colour of Magic a try to see if I still hate Rincewind, I read Guards! Guards!, I’m almost done with Men at Arms and...

they are just Okay. they’re Fine. one might even go so far as to say Good, insofar as I do think they’re very clever and fun and obviously earned their positions as classics of the genre (having thoroughly supplanted most of the earlier material that created the substrate that makes them funny), but I just don’t enjoy them that much. I don’t really want to read forty of them. the City Watch books particularly are very charming pieces of worldbuilding, a gem of a city to wander around in, I like Carrot, I like Vetinari, I like Vimes, but they are excruciating as mysteries. you figure it out around 100 pages in and then go, “god damn, you schmucks are going to take 200 more pages to get anywhere on this case??” and sort of slog onwards with the hope that at least maybe you’ll learn some more about Ankh-Morpork. and Rincewind is indeed still completely intolerable.

people do say Pratchett got better as he went on, and that tracks with how much more I remember liking Wee Free Men (#30) than the rest of these. i will probably finish out the City Watch series and also the rest of the Tiff books. and then if I am not any more enamored I will call it a Fair Shake and give up

Area Man Struggles with Choice Between Basic Morality and Homosexual Desire Toward Worst Person Alive

found an Abra today, which brings my collection of Pokémon cards sourced exclusively from the library book drop to 39

on the left you will see my pride and joy, Inexplicably French Psyduck From The Board Books Section. holo Galarian Moltres V 097/198 Chilling Reign is pretty cool too I guess

(not pictured: one each of Psychic, Fire and Electric energy cards)

i spent like. all day doodling cats

i'm still doodling cats

reblog if you need a hug

Reblog to give the person you reblogged this from a much needed hug

every time someone says “animals keep evolving into crabs” i’m like. head in my hands. no they fucking DON’T. carcinisation isn’t an animals thing. it’s a crustacean thing. it’s literally JUST CRUSTACEA

the thing is, carcinisation really isn’t about a tendency of convergent evolution in general. terrestrial vertebrates keep becoming vaguely shark-shaped in order to go back to being marine organisms (cetaceans, ichthyosaurs, mosasaurs, plesiosaurs, sirenians, thalattosuchians, seals, arguably otters, loosely demostylians), but we don’t have a cute little word for that because a bunch of guys independently coming up with the same body plan for the same niche is just, like, that’s how convergent evolution works. carcinisation is trying to describe something weirder, actually

The word is Pisciform.

There's not a word for the process, but Pisciforming, Pisciformation, or Pisciformisation would do in a pinch until some mad Icthyomancer divines a more appropriate incantation.

oh yeah, I’m well aware of what the general body plan is called (also sometimes ichthyomorphic). it’s just that the process of taking advantage of an aquatic niche by evolving a pisciform body plan isn’t really analogous to carcinisation, which is, rather than a broadly generalizable strategy for a certain niche, a very specific evolutionary tendency of the decapod infraorders Brachyura and Anomura (together clade Meiura).

per your other reblog:

the worm thing is literally so real though like. these are respectively a fish, a clam, a crustacean, and a cnidarian (jellyfish). there is only one step and it IS worm

(image sources: pearlfish, shipworm, tongue worm, myxozoan)

i wonder who in baru's life is completely different from tain hu except she finds her frustrating and doesn't agree with her but is utterly devoted to her in the end. i wonder who would be impressed by her having masts in her brain. a sailor, maybe

every time someone says “animals keep evolving into crabs” i’m like. head in my hands. no they fucking DON’T. carcinisation isn’t an animals thing. it’s a crustacean thing. it’s literally JUST CRUSTACEA

Silmarillion fans will hate to hear about this

kanafinwë makalaurë fëanorion, kinslayer, exiled and dispossessed, also sometimes known as Crablor, is indeed not of crustacean descent and his accursed fate shall bear no comparison to the natural inclinations of the crabfolk

every time someone says “animals keep evolving into crabs” i’m like. head in my hands. no they fucking DON’T. carcinisation isn’t an animals thing. it’s a crustacean thing. it’s literally JUST CRUSTACEA

the thing is, carcinisation really isn’t about a tendency of convergent evolution in general. terrestrial vertebrates keep becoming vaguely shark-shaped in order to go back to being marine organisms (cetaceans, ichthyosaurs, mosasaurs, plesiosaurs, sirenians, thalattosuchians, seals, arguably otters, loosely demostylians), but we don’t have a cute little word for that because a bunch of guys independently coming up with the same body plan for the same niche is just, like, that’s how convergent evolution works. carcinisation is trying to describe something weirder, actually

it's true. and part of it is just... how do you pick up a crustacean body plan and make it really mobile, ideally without risking drying out too fast? not just fast, but make it easy to quickly move in whatever direction you want, while also staying an invertebrate with a largely inflexible carapace?

Weell, the best way to increase agility and make lateral movement easier is to shorten the length of the abdomen and make legs real long, so you can quickly move in any of several dimensions at once and easily adapt to new places.

bluntly you could equally argue that it's spidericization within arthropods rather than carcinization broadly, you get the same patterns of "make abdomen real short / leggies real long" there among arthropods too, it's just that I don't think other terrestrial arthropods have faced that level of selection on terrestrial mobility.

you could also make up a line like "burrow snakicization" to refer to the way that digging, burrowing, or underground-living vertebrates tend to develop shorter legs and longer bodies: snakes, glass lizards, salamanders, mole rats, any number of rodents really, mustelids.. and so forth.

well, actually, it’s even weirder than that, because like, all of that is true, those are some of the selective pressures driving this specific example of convergent evolution. but 1) "shorten abdomen, lengthen legs" is not actually what carcinisation is and 2) carcinisation is not even a phenomenon of crustaceans. it's just one fucking clade in the decapods. i'll come back to that.

wrt what carcinisation is: most crustaceans are pelagic, swiming in open water, where shrimp and shrimp-adjacent shapes are king and are never gonna carcinise. in these circumstances, the "typical" crustacean body of Basically A Shrimp is plenty mobile. The pelagic shrimp bauplan only becomes a mobility issue for demersal or ground-associated species.

compare: Melicertus canaliculatus and Pandalus borealis, respectively a dendrobranchiate prawn and a caridean (true) shrimp, which both primarily locomote by swimming. Note long, powerful pleon (the entire abdominal section including the tail fan).

In contrast, the reef-associated species Gnathophyllum americanum, Heptacarpus palpator, and Stenopus hispidus all have shortened abdomens (although leg length is variable). Similarly to spiders, they're overall shorter and they concentrate their legs into the middle segments in front of their squat pleons. Just like crabs, they can move forwards and sideways, and they're way better at "backwards" than crabs are. They also retain the uropod escape response (tail goes flick, shrimp goes elsewhere) to get places in a hurry, something crabs have lost. If you're an inflexible arthropod and you want a demersal body plan that allows for movement along multiple vectors, be a shrimp!

If we're talking "spiderization" (arachnidization?), then most of the demersal shrimp qualify. But these are not crabs. This isn't carcinisation.

What carcinisation is (Keiler, J., Wirkner, C. S., & Richter, S. (2017). One hundred years of carcinization – the evolution of the crab-like habitus in Anomura (Arthropoda: Crustacea). Biological Journal of the Linnean Society, 121(1), 200–222. doi:10.1093/biolinnean/blw031):

what's really fucking weird about carcinisation: most of the crustaceans aren't doing it.

for those not up on crustacean taxonomy, there are like, twelveish big groups in Crustacea, the most popular being Eumalacostraca, which is most of the main guys people think of when you say “crustacean.” there are thirteen extant orders in Eumalacostraca. the only relevant one is Decapoda, which contains prawns, other prawns, slipper lobsters, regular lobsters, not lobsters, true shrimp, boxer shrimp, burrowing shrimp, burrowing shrimp two electric boogaloo, guys with four pinchers, and our two Main Characters, Brachyura and Anomura, which form a clade together called Meiura. the decapods are collectively a very diverse and successful clade!

and of all those different groups, those last two are the ONLY ONES which make crabs. Brachyura is the True Crab infraorder: they figured the body plan out in the early Jurassic and took off. there are ~14,000 living decapod species and 7,000 of them are brachyurans. they are the ur-example of carcinisation.*

* the only earlier example I know of is Cyclida, formerly Cycloidea, which 1) is incertae sedis and 2) has been extinct since roughly the time Brachyura showed up.

Anomura is Brachyura’s weird younger sister; they diverged from Brachyura in the late Triassic, when they started doing weird shit. namely they turned into hermit crabs, which are bizarre because unlike basically all other crustacean groups, the hermit crabs are skimping on the calcium. they've got soft squishy pleons! this is cheaper growth-wise, but requires them to find environmental armor to make up for it. they also did some other weird shit like mole crabs and squat lobsters.

every single group that evolved the crab shape after Brachyura is from Anomura.

every single one! all of them! the king crabs, the porcelain crabs, the hairy stone crab, the coconut crab—all anomurans. there are true crabs and then there are anomuran crabs and NOBODY ELSE is doing crabs. None of the other crustacean groups make crabs. None of the other decapod groups make crabs. it’s JUST FUCKING ANOMURA. they’re still doing it, too; king crabs came out of the hermit crabs only recently, in the Cenozoic. It's not clear exactly what the common ancestor of Anomura looked like—because they split from Brachyura, it's possible they originally looked like crabs, lost the crab shape, and secondarily re-evolved it. it might have been a bit like a frog crab, which are quite primitive. there's some good evidence that, whatever its ancestors looked like while they were still counted as part of Brachyura, the ancestral anomuran was a "symmetrical" hermit crab like Pylochelidae, which have a soft pleon but are not "handed" and have no abdominal curl. (These guys armor with hollow wood, tusk shells, sponges, and bamboo instead of snail shells.)

and it turns out that the hassle of locating and maintaining all that environmental armor is annoying enough that the anomurans have, four separate times, changed their minds and decided that tucking their soft parts underneath and returning to the tanky Crab strategy is a better option. six times, if you count the two separate times they went from the squishy symmetrical hermit body plan above to squat lobsters, which are sometimes considered an example of "partial" carcinisation.

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so carcinisation is not about convergent evolution as a general phenomenon. I would hesitate to even analogize it to phenomena like the strong evolutionary trend of teleosts towards skeletal fusion; most examples like that are really big trends, across broad clades, you know? carcinisation is One Weird Thing that Meiura is doing. and boy is it fucking weird