Hey y'all. Lighter effort-post this week in the interest of not kerploding myself. I'm not gonna hold to a precisely weekly schedule because someday the effortposts will return and those will be biweekly by necessity. But in the meantime I can talk about lighter, less explain-y shit.

A Personal History of Crabs

So as someone who's worked a few years in coastal ecology, I have had to interact with crabs a bunch. They're abundant little fuckers and of pretty high interest to humans, whether because we like eating them, or because they like eating things we eat (i.e. oysters). Personally I find them kind of high effort for little meat compared to like, clams or lobsters, though I'd be lying if I said it wasn't fun to just crack one entirely open and scoop out the innards. The soft animal of my body enjoys eating whole seafood.[^1]

There are 4 kinds of crab I've had a lot of close contact with and therefore have warm fuzzy feelings about. Two of which were for science and job reasons, and the other two of which is for them being all over the place. Honorary mentions to these guys include:

Mud crabs (Panopeus herbstii)

and Fiddler crabs (several from the places I've worked, but the specific one here is Leptuca panacea)

Both these guys were all over the marshes and beaches. Mud crabs in particular are popular residents of oyster reefs, where they can use all the various nooks and crannies between the shellfish to hide. Which is good, because while they're still predators, they're tiny as hell and therefore common pickings for larger crabs, or fish. The fiddlers were fun because whenever I would walk down to the beach to see a particular field site, you'd see them all swarming away from the people, or the water when the waves came in. The oversized claw is a feature of sexual dimorphism, and the males use them to fight (and, occasionally, to plug the mud hole they've buried themselves into). You could look at a marsh bank when the water was low and see the mud all pockmarked with holes. There's lil guys in there.

As for the science buddies. These two are the crabs I have the most Thoughts And Feelings about, and they are hilariously different from each other.

Most everybody knows about the first one. The prototypical US east coast crab. The one, the only, the crabson,¹

Atlantic blue crab (Callinectes sapidus)

My current job has this exact photo as a big fabric print on campus somewhere. It's fantastic. I love it to bits. If I had more gumption and spare time I'd have gone and grabbed a photo of it myself.

Anyway. These are the first crabs I ever worked with. I have the scientific name memorized after working with and talking about them so much. Fun fact, the genus name Callinectes comes from the Latin for "beautiful swimmer". This is from the two paddle-like swim fins on their last set of legs, which they do in fact use to swim around. There is some irony to hearing them called "beautiful" when you've mostly seen them act derpy or try to kill each other, but having actually seen one swim in the wild, they move through the water incredibly smoothly. And yes they swim sideways too. Hydrodynamic body shapes for the win.

When you research clams and oysters, crabs are also a huge deal just because they eat the shit out of your study organism. Blue crabs are generalist scavengers who've made it their life's business to play garbage disposal to the entire rest of the estuarine food web. And as it turns out, oysters who make 5 million babies per spawning season (not accurate estimate) which then come down out of the water column and onto the seafloor en masse in tiny hard-shelled blister packages of meat, make for a fantastic food source. So they hang around reefs a fair bit, and will also come absolutely gunning for you if you've just put out a big restoration reef full of 2 week old babies. Dealing with predators is also one of the big reasons why restoration projects have low survival rates - you're dealing with the exact same reason why oysters and other clams make 5 million babies in the first place. You need 5 million babies to have 500,000 that make it.

Anyway. I've had a lot of run-ins with blue crabs both in the wild and in the lab. They're easy as hell to work with because you can put out baited crab traps and get 1-2 per week per trap depending on the weather and time of year.² And they're hardy fuckers who're therefore easy to keep en masse in a tank. If you're at a marine science lab you'll have plenty of oysters or dead fish to throw at them for food. The only problem is they're aggressive and cannibalistic. Feeding time at the lab was fun because when you threw stuff into the tank, they'd all go running and start tearing up chunks, or picking up the smashed oyster and walking them back to an unoccupied corner, waving claws the whole time. But also if a crab molted in a group tank, that poor fucker was going to be killed and eaten by their tankmates. In grad school we kept our blue crabs in big long aquaculture cages - big thick plastic mesh cages for farming clams. That way they could have individual "crab condos" (as my labmate put it), or else a duplex with a dividing wall in the middle. They'd get their own food, and could molt in peace without getting beaten to shit or claws torn off. Which did lead to funny incidents of walking into the tank room on feeding day and being startled by Two Crabs in the crab condo - a crab molt looks startlingly similar to just a regular crab.

My favorite photo of a fully intact molt is this one, which the postdoc saved as a present for his now-partner.³

And then, on the polar opposite end of the temperament scale, we have my now favorite crab,

Florida stone crab (Menippe mercenaria⁴)

There are few crabs better placed to snap your finger like a twig, but also few crabs that are less inclined toward violence than this guy. They're shellfish eaters and therefore are built like fucking tanks so that they can crack stuff open with relative ease. Unlike the blue crabs, however, which could and would try to fistfight us at every turn, stone crabs were comparatively mellow. You could pick them up and they wouldn't try to pinch at you, or at least they wouldn't flail with the full-body gusto for violence against your hands. Granted, when we had to extract urine from them for Science Reasons (more on that for a future post), you would need someone to hold them down lest they injure themselves on the lab equipment or they broke the aforementioned postdoc's fingers out of self-defense.

There's a fishery for them in Florida, specifically for their claws. I've never had stone crab, but I imagine with a claw that big they've got a good chunk of meat in there, not dissimilar to how king crabs are sold by the leg. Unfortunately this does also mean that there are a lot of one-clawed stone crabs in Florida, because they're basically caught and declawed before being thrown back. A crab can definitely get by with a single claw (and lots of crabs can and will just tear away from their limbs to escape capture), but it does put them a smidge at a disadvantage to have just the one (or else to have one full size claw and one freshly grown piddly looking new claw).

Anyway. I find these guys deeply charming, both because they look cool as hell, and because they're so well behaved. Not nearly as hardy as a blue crab, though. We had a couple of mass stone crab die-offs in our lab tanks over the field seasons we were keeping them. I have a stone crab-themed character in the ICON campaign I'm in, because I like them so much.

Sources:
https://www.chesapeakebay.net/discover/field-guide/entry/black-fingered-mud-crab
https://en.wikipedia.org/wiki/Leptuca_panacea
https://www.fisheries.noaa.gov/species/blue-crab
https://en.wikipedia.org/wiki/Florida_stone_crab
https://en.wikipedia.org/wiki/Menippe_adina

1. See Marine Science Mondays #4. Krabby Crabson is not a blue crab but it's extremely funny to make him act like one.

2. Alternatively, as I found out during my internship, you could catch a reproductive female, and have 7 males crowding in that cage with her, including one that's clambered on to guard her.

3. The biologist's propensity for dead things also makes for convenient gifting strategy during courtship.

4. I'm realizing only now that there are two species of stone crab - Menippe mercenaria which is the photogenic beastie here, and Menippe adina which is a much less colorful stone crab and the ones which I was dealing with on a regular basis.