Fun fact: horseshoe crabs are not only not crabs (infraorder Brachyura), not only are they not decapods (order Decapoda), and not only are they not class Malacostraca, they’re not even crustaceans (subphylum Crustacea).
Instead, they’re in the subphylum Chelicerata, making them more closely related to a tarantula, a daddy longlegs, and a tick than they are to any crab.
They are part horse though, right?
Actually, part shoe.
And like many a shoe, has 10 eye-let
My favorite horseshoe fact is that they have nine eyes, of all different types. And that’s not even counting the tail which is itself covered with photoreceptive cells - so it’s essentially a tenth eye.
be not afraid
I was under the impression that chelicerates were categorized as crustaceans, along with hexapoda. I’m not an expert in this, I just watch the phylogeny videos of Clint’s Reptiles and AronRa.
Close. Arthropoda is the phylum under Animalia. From there you have the four subphyla Crustacea (crustaceans), Hexapoda (insects), Myriapoda (centipedes and millipedes), and Chelicerata (chelicerates). So they are closely related relatively speaking, but they’re separate subphyla.
If anything, funnily enough, the clade Pancrustacea is comprised of just crustaceans and hexapods to the exclusion of myriapods and chelicerates. Even more messy – I learned just now that – is that Arthropoda can be divided into two clades Chelicerata and Mandibulata (where Mandibulata contains myriapods and Pancrustacea), so in reality, not only are horseshoe crabs more closely related to a black widow spider than to crabs, but crabs are substantially more closely related to a mosquito than to horseshoe crabs.
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Welcome to Arthropod Facts! Did you know that king crabs aren’t actually crabs? King crabs (family Lithodidae) sit in the hermit crab superfamily Paguroidea in the decapod infraorder Anomura, whereas true crabs comprise the decapod infraorder Brachyura. The current strong and widespread scientific consensus is that king crabs are hermit crabs which originated in the North Pacific about 15 million years ago and evolved a crab-like, calcified exoskeleton through carcinisation.
Evidence for this includes:
- King crabs exhibit the same asymmetries that hermit crabs do, such as the asymmetrical abdomen (underside) found in females but not males.
- Lithodidae can be divided into the two subfamilies Lithodinae and Hapalogastrinae. Respectively, these have a calcified abdomen and an uncalcified/partially calcified abdomen. This suggests that Lithodinae fully calcified whereas Hapalogastrinae only partially calcified.
- Many king crabs (mainly Hapalogastrinae) are exclusively distributed in the North Pacific and are adapted to only living in cold waters.
- Molecular phylogenetics (the study of things like how species differ in their DNA) strongly suggests that Lithodidae is most closely related to the hermit crab family Paguridae.
An easy way to distinguish a king crab from a true crab is to look at the number of visible legs it has. While all decapods have ten legs, the last (hind) pair of legs in king crabs are dramatically reduced in size and usually sit inside the branchial chamber – used for cleaning rather than walking. By contrast, crabs always have their last pair of walking legs, although in the crab superfamily Portunoidea these are flattened and used as paddles for swimming. Thus, when counting the chelipeds (claw-bearing arms) as legs, you’ll see eight legs on a king crab (four rows of two) and ten legs on a true crab (five rows of two).
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Thank you so much!
Thanks for the info, I love learning this kinda stuff.
A fellow Clint’s reptiles enjoyer?
Is that a YouTube channel?
It is! he’s a biologist that has gone through phylogenies of many living creatures with the goal of hitting every clade I believe. I’ve found him recently, so I can’t say I really know. But, I’ve been watching a lot of it. It’s fascinating.
Omg that’s so cool. New thing to binge at work on slow days. 😎
Thanks!
Well that checks out, considering they are more terrifyingly stranger then any other crab.
That would honestly make my fucking year!
That’s a two full size Snickers bars worthy costume.
Yep, reward the creativity!
This is why I love Halloween. Some kid wants to be an umbrella. Another wants to be a tornado. Then, Yoshi to shows up to get candy, but right behind him is his little brother dressed like the elderly ghost of Tupac. Bro wut.
I fucking love it.
One of my favorite Halloween costumes is still a college acquaintance who came to the party as a banana slug. It was so sincere and heartwarming!
Do you want Aubrey Plazas, Lana? Because that’s how you get Aubrey Plazas.
(I put way too much into pondering if it should be Aubries Plaza.)
“Surgeons general” energy.
Oh we should definitely be encouraging this then (I do mean this sincerely, I feel like this could read sarcastically but it isn’t meant to be)
If I saw her crawling after me, I might actually shit my pants. Seeing that thing crawling around a suburban street would be way scarier than some disheveled clown
Why wait?
Twist is she grows up, starts menstruating blue
I’d fucking love both the creativity as well as the effort involved getting the background knowledge. That’s why it’s two full size milky ways.
I’m just wanting somebody to post a link on how to make that costume. It’s awesome
Couple of Hula hoops maybe?
I am so impressed at the construction of the costume! Damn I wish there was a video of it being made.
Right? Look at the craft!
This girl is going places in life.
Door to door?
And the floor!
Fuck it, she wins Halloween. She gets the whole bowl. Turn off all the lights and lock the door.
Careful, people might try to steal her blood!
First thing I thought about the skateboard is that he’ll not be watching where he’s rolling, and just gets driven over by a car
