#anomura

[alphynix]

Strange Symmetries #13: The Hermit Crab Cycle

Hermit crabs are crustaceans that first appeared at the start of the Jurassic, about 201 million years ago. Despite their common name they aren't actually true crabs, instead being a classic example of convergently evolving a crab-like body plan via carcinization.

They also have noticeably asymmetric bodies, with abdomens that coil to one side and differently-sized front claws.

Pagurus bernhardus by Arnstein Rønning | CC BY 3.0

And while modern hermit crabs are famous for inhabiting scavenged snail shells, their fossil record suggests this wasn't always the case.

Originally, they seem to have lived in ammonite shells.

Palaeopagurus vandenengeli lived in what is now northern England during the Early Cretaceous, about 130 million years ago. Around 4-5cm long (~1.6-2"), it was found preserved inside the shell of the ammonite species Simbirskites gottschei.

Its left claw was much larger than its right, and together they would have been used to block the shell opening when it was hiding away inside. And while the exact shape of its abdomen isn't known, it probably asymmetrically coiled to the side to accomodate the spiralling shape of the host shell.

Hermit crabs seem to have switched over to using gastropod shells by the Late Cretaceous, around 90-80 million years ago, possibly due to marine snails developing much stronger sturdier shells during this period in response to the increasing prevalence of specialized shell-crushing predators. The more upright snail shells would also have been much easier to drag around the seafloor than ammonite shells – and meant that they were ultimately less affected by the total disappearance of ammonites during end-Cretaceous mass extinction.

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[ketrinadrawsalot]

Decapocember Day 4: The infraorder Anomura is full of decapods called crabs that aren't actually crabs (brachyurans are true crabs). Carcinization led to many of them becoming crab-shaped. One feature common in anomurans is that two of their appendages are significantly smaller than the others, making them look like they have eight limbs.

[patheticmosasaur1]

today's invertebrate..........albunea speciosa

albunea speciosa tends to the growth, trimming it whenever it pulsates and glibling to it when needed

however if the growth starts to popumble and shape then it'll have to be measured geometrically!!

I know this is really sad, but it has to be done, for albunea speciosa's safety, and for the many winds that gumb on unwanted skin

glorpiness rating: {{★☆★♤, but really unfortunate

source

[frumpytaco]

Got out on the rocks this weekend to celebrate Tiny Crustacean Fest.

Top: the tide was really fuckin low

2nd row: A very distressed mother and the brood of babies she released from her marsupium when I put her in the water to look at. :( Absolutely refuse to make an ID on her.

3rd row, left to right: Ischyroceridae (Ischyrocerus?), Aoridae (Aoroides?), Sphaeromatidae

4th row, left to right: Melitidae, Ericthonius sp.

5th row, left to right: Petrolisthes cinctipes, Romaleon branneri, Cancer productus

6th row, left to right: Hemigrapsus nudus (I've never seen one so big in CA!), Lophopanopeus bellus, some weird orange thing without an exoskeleton idk (jk i'm pretty sure it's Triopha maculata)

[birdblues]

Three-lobed Porcelain Crab

[typhlonectes]

Aeglidae

The Aeglidae are a family of freshwater crustaceans currently restricted to South America. They are the only anomurans (hermit crabs, squat lobsters, et al.) to be found in fresh water except for a single hermit crab species, Clibanarius fonticola, on Espiritu Santo, Vanuatu. 

Aeglids resemble squat lobsters in that the abdomen is partly tucked under the thorax. The notable sexual dimorphism in the abdomen is related to the behaviour of carrying fertilised eggs on the pleopods.

Aeglids are omnivorous, preferring plant matter, but also eating adult insects, molluscs, fish and fly larvae...

Read more: https://en.wikipedia.org/wiki/Aeglidae

photograph by Jaocowiki | Wikipedia CC

[crabmeiser]

THIS IS NOT A CRAB

THIS IS AN ANOMURA AND IF I HAVE TO EXPLAIN TO ONE MORE PERSON THAT COCONUT CRABS ARENT ACTUALLY CRABS, I AM GOING TO GO INSANE.

crab of the day is...

the coconut crab (birgus latro)

fun fact: i have reoccurring nightmares about these things!

real fun fact: they are the largest known terrestrial arthropod!

[anomura]

achelata –> anomura

[forsuperbang]

I couldn't be a carcinologist, it seems too overwhelming (but awesome!)

[historicalbookimages]

🔭 Report on the Crustacea (Brachyura and Anomura) collected by the North Pacific exploring expedition, 1853-1856 City of Washington, Smithsonian Institution, 1907.

[daily-crabbys]

hello!! i have a crab fact!! (sorry if you arent taking submissions for crab facts i just thought i would supply a fact!)

the main difference between "true" and "false" crabs is how many legs they have. true crabs have eight legs, while false crabs have six!

around 250 million years ago, crab lineage split into two main groups, Brachyura (true crabs) and Anomura (false crabs)!

https://www.abc.net.au/news/science/2022-09-18/crab-convergent-evolution-crustacean-australia-marine-biology/101388282

^ this is the source i found it from by the way, i would recommend reading it since i'm not the best at explaining it! thats all from me :)

Crab Fact(summarized): The difference between true and false crabs is the number of legs that they have.

[wrmhles]

describe yourself with 10 photos already on your phone!!

tagged by @survivedthenight and @drylite lalala love u guys

tagging @medarda @anomura @pauliemartins and im double tagging @galetops but no pressure anyone heheee <3

[survivedthenight]

tagged by @london-cowboy thank you sm!!

Last song: whiplash by aespa. it's been on repeat for like a week.

Currently watching: ER! half watching half rewatching as i've already seen the later seasons. and it's SO GOOD. need people to talk about it with if anyone has seen it

Last movie: .... this was a struggle to remember. think it was dune 2???

Relationship status: single

Current obsessions: mota... also sudoku

Last thing you googled: "persistent cough not sick" lmaooooo why won't it go away

Silver or gold jewelry: silver

Do you have any tattoos: no but i would like some!

Piercings: none! used to have my ears pierced by they got badly infected a few times so i gave up.

Currently reading: nothing atm! last book i read was in memoriam by alice winn back in september. liked it a lot! have a stack of unread books waiting for me to pick from. i'm thinking of the sparsholt affair by alan hollinghurst but who knows. i'm so terrible at reading atm

Hobby you would like to try: pottery!

Coffee or tea: tea 100%

Favourite video games: i am not a gamer girl

Star sign: sagittarius. i'm not really into starsigns but from what i've read i'm not too sure how well sag fits me lol

tagging @onceandfuturebitch @anomura @drylite @wrmhles @juneebugs @onyxsboxes but no pressure! and whoever else would like to do it!

[majorbuckyegan]

5 (more) boring facts about me

Thank you for the tags @caustinen and @caterina07121 🫶

I can't cook to save my life, but I can bake

I used to have a bracelet made of john taylor's (from duran duran) bass strings, but I lost it :(

I'm left handed

I've only ever lived in one house my entire life

I've worked in a hospital for the last eight years

Tagging: @swifty-fox @spaceshipkat @angelfruittree @anomura @amiserableseriesofevents @whirlpool-blogs

[typhlonectes]

Description of a new species of the Petrolisthes galathinus complex from the Caribbean Sea, and resurrection of Petrolisthes occidentalis from the East Pacific (Crustacea, Anomura, Porcellanidae)

Alexandra Hiller, Bernd Werding

Abstract The Petrolisthes galathinus complex currently consists of six American species distributed in the West Atlantic, including the amphi-American P. galathinus. All species in the complex are similar in their adult morphology but differ in colour, size, larval morphology, and shape of the adult sternal plate. The West Atlantic species have different geographic ranges, which overlap in the southern Caribbean. Previously published molecular data support the monophyly of the complex, and the reciprocal monophyly of each described species and further clades corresponding to different colour morphs. Here, the morph P. caribensis “Blue” is described as Petrolisthes coeruleus sp. nov., and Petrolisthes occidentalis is formally resurrected for the Pacific individuals of P. galathinus. By adding these two species to the P. galathinus complex, this now consists of eight species. Colour illustrations of all species and colour morphs are provided and their geographic distributions and ecological ranges are discussed and updated.

Read the paper here:

Description of a new species of the Petrolisthes galathinus complex from the Caribbean Sea, and resurrection of Petrolisthes occidentalis from the East Pacific (Crustacea, Anomura, Porcellanidae) (pensoft.net)

[wwasted]

thank u for the tag @polifandom, my beloved <3

last song: gay rude boys unite by leftover crack bc this line is speaking to my queer rage in these trying times "so, come on, leave the closet / on your way out, grab a bat" (also tw I guess? jsjakkas it feels so dumb to put that for leftover crack song but this is tumblr so)

favorite color: sage green, burgundy, or dark brown.

currently watching: just finished the pacific... need 90 days to process.

currently reading: nothing bc i can't read while writing fic. my brain won't Allow it.

last movie: A Lot Like Love... (more on that later js)

sweet/spicy/savory: depends on the mood. I have a killer sweet tooth but I also love savory foods.

relationship status: married! to my beautiful little gremlin of a husband, he's my bbygirl for life.

current obsessions: mota lmao I tried having other obsessions but they beat the shit out of them in my head until they were the only ones left.

last thing you googled: dispensaries near me kdkaskdsa

tagging @blixabargelds @middlingmay @wayrad @anomura honestly everyone bc i am nosy and would love to be fed lil tidbits of info about cool people