Horseshoe Crabs?

[velvetundergrowth]

As is probably obvious by now, I really have a thing for obscure and ancient invertebrates. And in around 2 weeks I will be receiving one of the most interesting and iconic of the "Living Fossils" - a Horseshoe Crab!

For those of you that don't know, Horseshoe Crabs (Xiphosura) are not crustaceans but in fact close relatives of the Arachnids, with recent genetic research placing them closer to Ricinulei than any other living animal. If fact, it may transpire that Horseshoe Crabs do in fact belong in Arachnida, however this is the subject of much debate.

It has been a long time since I have experienced one of these incredible chelicerates as they are very seldom imported here. I have kept one of the Asian species, Carcinoscorpius rotundicauda, in a brackish community tank for a while but sadly that tank no longer exists and its inhabitants were returned to the LFS (That is, the ones who were not devoured by the puffer!).

What I want to know is any of you have any experience with Horseshoe Crabs? I know they have a less-than-flattering reputation as additions to reef tanks, however it will be housed in a species-specific tank.
I'd love to hear from anyone who has kept these creatures before, there must be at least one of you on here!

 

[pannaking22]

There was a pet store I went to regularly that would have horseshoe crabs from time to time. Super cool inverts, if I wasn't a broke college student with no space at the time I probably would have gotten one.

 

[mantisfan101]

Keep us updated on this; how big are the horseshoe crabs? What species? Also don’t they grow extremely large? What size tank do you have setup? I’m eager to see how this’ll work; I’ve only occasionally seen them for sale.

 

[velvetundergrowth]

There was a pet store I went to regularly that would have horseshoe crabs from time to time.

From what I can tell they are commonly offered over there in the States, but most LFS have no idea about their actual care requirements (they are sold as 2-3 inch juves) and the majority die within months from starvation, lack of a deep sand bed, high temperatures (most species are temperate) or a combination of the three. Also, 3 of the 4 species, although slow-growing, reach sizes well over a foot in length so require large aquaria in the long run.

In other words, they are not ideal additions to the general marine aquarium. In my opinion tho, they are unique and interesting enough to earn their own tank

 

[velvetundergrowth]

Keep us updated on this; how big are the horseshoe crabs? What species? Also don’t they grow extremely large? What size tank do you have setup? I’m eager to see how this’ll work; I’ve only occasionally seen them for sale.

I'll be sure to update.

I'm rehoming an unwanted HSC. The guy who posted the classified wants rid of it as he wants to stock more Coral in his reef tank, and is therefore free to a good home. I'm hoping to provide a better home than a cramped cube with minimal sand bed!

I am not sure as to the species but research has told me most of the HSCs imported to this part of the world are C. rotundicauda. Judging by the photos it seems it is indeed this species; the colour of the carapace and overall shape seem consistent with C. rotundicauda.
I'm crossing my fingers for the Mangrove HSC as it is smaller and I already have some experience.
If it is an Atlantic HSC I will have to modify my plans slightly, but seeing as I will be keeping it by itself that will mostly consist of removing the heater and letting the tank remain at a cool, Irish room temperature. This species requires a tank of at least 1,000 gallons as an adult and would require a significant investment... although the idea of a huge, Bond-Villain-esqúe feature tank along one wall housing a large Horseshoe Crab is oddly tempting

The tank will for now consist of a 50g (shouldn't be too uncomfortable for a 2" specimen for a year or two) long with some minimal live rockery in one corner and a 3-4in unobstructed live sand bed.

 

[Salmonsaladsandwich]

I'm not so sure high temperatures are a factor that would do horsheshoe crabs in. Atlantic horseshoes not only spend quite a bit of time in shallow estuaries that get warm in summer, when they spawn they crawl up on the beach and frequently become stranded. They can survive quite awhile baking in the sun before the water rises high enough or they finally die of dehydration.

When you see horsheshoe crabs like this, often they are still alive and will survive just fine if you flip them over so they can return to the water.