freshwater horseshoe crabs

[nmonks]

Folks,

Someone e-mailed me this week about a "freshwater horseshoe crab" he bought from the Waterlife Centre near Heathrow, West London. Turns out that these are indeed the elusive Carcinoscorpius rotundicauda or mangrove horseshoe crab. This species is truly euryhaline, and while it is primarily an estuarine animal, it has apparently been collected 50km upstream in one river, as well as being found in shallow marine environments.

For anyone after a brackish water invert, this would make an outstanding choice. Supposedly quite hardy, though all horseshoe crabs do need things like sand for digging and suitably sized meaty foods to eat. They're also pretty big, around 20 cm across the shell, and as much again for the tail.

If you aren't local, then at least you can take comfort that these things are on exporters' lists. Quite possibly worth asking your retailer to obtain.

Cheers,

Neale

[The Fisherman]

Sweet, I might have to look into that.

[Peregrine]

That would be really interesting to have one...but dont have a tank large enough...yet

[OraLacerta]

That is so exciting! I love horseshoe crabs- they have always fascinated me. I will definitely have to look into that, thanks for the heads up!

[Jason]

i've been looking into marine horse shoes for awhile since the last time i saw some come in at work. i'll have to ask around and see what i can come up with. if i ask the wrong person they'll just acclimate marine species and double the price....i hate some dealers at times.

though a BW horse shoe would be cool i'm not even sure about the long term survival of marine species...hard to find husbandry info on them.

jason

[PetPirate]

Very cool.... but horseshoe crabs are a bit too "spider-like" underneath for my tastes....

[Boxermom]

How much is known about caring for them in aquaria?

[Pufferpunk]

Would a toby eat a SW one?

[The Fisherman]

Would a toby eat a SW one?

If the Horseshoe crab was big enough, I doubt it. But then again, i'm mostly guessing here. You could try it and tell us how it goes

[Jason]

most of the marine species i've observed at work (probably just a bunch of the same species, i'll try and figure out which one next time we get some in) spend most of their time nearly buried in the sand. i'm not sure most tobies....errm...tobys..well anyhow i'm not sure the would notice them unless they happen to come up for something.

jason

PS though they are really determined hunters at times (tobies that is) so they might wonder what the ambulatory bump in the mud is.

[nmonks]

As Jason said, these things basically stay in the sand. It needs to be pretty deep for them to be happy, or else they have problems because the water current tips them on their backs. Also, they only eat very small animals (no jaws) and so you need to bury things like bloodworms into the sand for them to sift out. There's a nice FAQ on caring for horseshoe crabs at the Wet Web Media web site in the marine inverts section.

None of these horseshoe crabs are "easy", and if you're considering one, get one shipped in as a marine and then adapt it to brackish water. Specimens kept too long in freshwater don't seem to last long, though this may be more about not feeding properly than anything else. Also, bear in mind they get pretty big.

Cheers,

Neale

[Pufferpunk]

I suppose a toby would eat one (the SW kind)?

[nmonks]

I can't see how; a happy horseshoe crab is an invisible horseshoe crab. The shell is big and smooth, and unless the puffer dug the crab out from the sand and flipped it over, it's pretty impervious. At least, this is true for adults, which have a shell length of 20 cm. Juveniles are obviously much more at risk.

Cheers,

Neale

[The Fisherman]

I agree, a toby would have to work really hard to even get a chunk out of it. Espeacially if they are that big.

Neale, have you kept horseshoe crabs before?

[Pufferpunk]

I plan on keeping a Dusky jawfish in my new tank, that requires a 5" sandbed to dig around in. I've seen these crabs at my LFS. What should I look for in a healthy one?