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FAQs about Horseshoe Crabs 2

Related FAQs: Horseshoe Crabs 1, & FAQs on: Horseshoe Crab ID, Horseshoe Crab Behavior, Horseshoe Crab Compatibility, Horseshoe Crab Selection, Horseshoe Crab Systems, Horseshoe Crab Feeding, Horseshoe Crab Disease, Horseshoe Crab Reproduction, & Crustaceans 1, Micro-Crustaceans, Amphipods, Copepods, Mysids, Hermit Crabs, Shrimps, Cleaner Shrimps, Banded Coral Shrimp, Mantis Shrimp, Anemone Eating Shrimp

Related Articles: CrustaceansMicro-Crustaceans, Amphipods, Copepods, Mysids, Isopods, Shrimps, Coral Banded Shrimp, Cleaner ShrimpP. holthuisi Pix, Mantis "Shrimp", Lobsters, Slipper Lobsters, Hermit Crabs, Squat Lobsters, Crabs, Arthropods, Pycnogonids (Sea Spiders),

Need sandy bottoms, of depth...

Horseshoe Crab questions       4/6/15
Hello guys, im Patrik, I have a 40B <G?> saltwater tank that's been running for a year and a half with a 10 refugium, all levels as low as stability allows salinity 1.026. The 40 has my salt cat and snowflake eel and the fuge is for my nems crabs and shrimp, well in my travels I was given a horseshoe crab about the size of a quarter in a gallon pickle jar. Its molted once in the 8 months I've had it and is now 2 1/2 inches. He eats shrimp pellets and crab meat and any krill that are left from the nems and seems pretty happy never had a single issue with him. In the past month I've noticed he likes to come out around noon and midnight, so lights on and off, and lay upside down on the sand in one particular corner with low flow. Im worried because it is strange but he stays still if I try to flip him
<Don't do this>
over like doesn't react at all for a minute, then even if im still messing with him he starts wiggling his legs so maybe sleeping or something and I have a 4' by 4' pool for him to grow into one day so id like him to live as long as possible.
Any and all help is very much appreciated, thank you.
<See (i.e. READ) on WWM re these animals.... You likely have a cold water (temperate) species (there are tropical ones though)... NOT suitable for a tropical setting. Bob Fenner>

horseshoe crab, fdg., sys. gen.     2/5/13
I have been reading and researching your site on horse shoe crabs and had a few things i wanted to discus with you. I have a little horse shoe crab
<The eastern seaboard species I'll assume>
 in a 10gal salt water tank. he was about 2 inch's when i got him, and now he is about 3 to 3 and a half. I have had him in the tank for about a year at this point and he has not starved to death. My salinity is between 1.024 and 1.025, ammonia and nitrites are both at 0 or close to, my nitrates are kinda hi, but they have always been high in my tank and despite anything i do i cannot get it to come back down.
<Not so important w/ these relic species>
 So far the only adverse affects to the high nitrates is a bit more red hair algae than i would like (the snails keep in under control for the most part) and my plant seems to like it as well (not sure what kind, obviously saltwater plant, its kind of  like a vine and it raises little stocks that disk shaped "leafs" grow on).
There is a very healthy bristle worm population in the tank as well as he seems to enjoy algae wafers made for Plecos and other such fish as well as high protein wafers made for catfish and other bottom feeders. He does seem to come out and eat with everything else in the tank and chasses around bits of flake food but his favorite seems to be Hikari Multi-Vitamin Enriched Brine shrimp. As for the trace elements in the tank, i use Kent Marine Nano Reef two part supplement. It is recommended for use every day, but i don't use it that way, i add that about one a week, sometimes twice if I'm feeling spunky. Tank mates include a mis-bar clown fish, a blue-green Chromis, peppermint shrimp, two Astrea snails, two dwarf blue legged hermit crabs and a group of about 9 Zoas. There was at one time a mini brittle star that came in with the Zoas, but i have not seen hide nor hair of that little guy in over 7 months so i think he died and got ate, or just got ate. There was a narsis snail and another Astrea snail, but the hermits wanted bigger shells and they didn't like any of the upgrades that i provided for them.
There is about 6 to 7 pounds of live rock, and about 20 pounds of live sand to make a sand bed of about 3 inches deep. The sand is larger grain, not fine grain, but he really does not seem to mind. I really love this little guy, he is awesome and by far the best purchase i have made. Hours of entertainment watching him walk around the sand eating, and swimming (not very well) upside down around the tank. And yes i know how big they get, i have already located tanks that he can be transferred to as he grows, including a fine grain, 6 inch deep sand bed in a 180gal tank with plenty of Spionid worms for him to break up and eat. I guess what i want to know is is there anything else i need to be doing for this little guy?
<Doesn't appear to be; no>
As i have stated he has had no problems so far, but i want to keep him this way. I have not found anything on your site with anything i really need to change so I'm just double checking that i have not over looked anything. its hard to know what your looking for when there is no problem to solve. thank you for your time and for your help! i greatly appreciate it.
<Well, the other life, fishes and invertebrates would likely appreciate lower nitrate... not easily done in the size/type setting w/ the horseshoe... All will appreciated the larger habitat. Bob Fenner>
Re: horseshoe crab    2/6/13

Thank you for the quick reply! any quick tips for lowering nitrates in a small tank other than moving them to a big tank? i would like everything to be as happy in the tank as can be.
<Read here: http://www.wetwebmedia.com/nitratesmar.htm
and the linked files above. The mechanisms, techniques of nitrate control are the same regardless of size of the system. BobF>
Re: horseshoe crab    2/6/13

thank you very much!
<Ah, welcome. B>

Touch Tank: Limulus polyphemus     6/17/11
To whoever receives this e-mail, I am seeking advise from the knowable marine invert expert who wrote the Horseshoe crab article here (http://www.wetwebmedia.com/hshoedis.htm)  . If you could point me in his/her direction I would very much like to ask him my quick questions:
I work at a museum that acquired a touch tank through the program (Touch Tanks for Kids) and want to use it to house horseshoe crabs from our local Chesapeake Tank. I have been placed as one of the lead members of this project however I have no experience with these magnificent animals and recently became aware of their intense upkeep. I was hoping that you could assist me in this matter because written below is what we have been brainstorming so far:
The tank is a little over a 100 gallons so we will keep one crab in at a time and rotate every other month or so.
<Mmm, I'd do this more frequently... even daily. Very stressful to be touched, confined in such a small volume>
Also since museum hours are noon-4pm we figured their stress levels wont be as high as other major aquariums. But the tank came with large rocks and we will remove it and add fine gravel/sand so the animal can dig.
We don't want to add sand in from the Chesapeake because we fear the microbes, worms and algaes will clog up the protein skimmer and filter units quickly (hundreds of dollars down the tubes).
<What will the animal/s eat then?>
The crabs in the main tank right now feed off the bottom as normal, but when they switched into the touch tank we will feed them bloodworms and diced molluscs. The tank has a chiller unit but I am thinking that a sudden change in temperature may shock the guys so we will try to make the touch tank only a few degrees cooler than the main one. This is as far as I have gotten, I do not know what sorts of chemicals to look out for or if we need to grow a bacterial culture for nitrates,
<What sort of filtration system does this unit have? You need circulation through this, to measure, assure that this system is cycled... Ammonia, nitrite>
also if adding other smaller life forms like shrimp or oysters could affect their oxygen requirements.
<Mmm, yes>
Any info you can add would be greatly appreciated. Thanks.
*John C*
<John... there is a bit of a steep learning curve ahead of you... I would ask for assistance from an aquarist/docent... Hopefully one with coldwater, local sea life keeping experience. Are you familiar w/ written works of David Wrobel re these? Please do a search for: Keeping Native Marine Fish in the Home Aquarium
Bob Fenner>

help ! What you find on/at the beach, stays at the beach...   8/20/09
Hi WWM crew,
This past Sunday morning about 7:30 am, I found a large horseshoe crab on the beach of Stone Island N.J. It was still alive and had just been washed ashore. I thought at first it was dead, but after I picked it up to look at it the legs moved a little and I walked back to show my family. This thing is so incredibly awesome and I want to save it's shell but how do I do that ?
<The shell or the whole animal? Take it back>
Is it too late for some one to use it for research ? It looks very old and it is 23 inches long and seems to have sandy looking disease on the top along with other spots and marks. Right now it stinks and I put it in a bag to toss but I'm sure some one can guide me to preserve the shell. The entire crab is intact. Also , can a disease be passed to humans from a sick sea animal ?
<... Please read here: http://wetwebmedia.com/hshoecrabsart.htm
and the linked files above. Bob Fenner>

Horseshoe crab, leave at the beach  8/9/09
I have questions because of a very stupid situation, as probably evidenced by the title, that I need to resolve.
Recently my family brought home a live horseshoe crab this past Friday (along with about a dozen horseshoe crabs which died upon the touch of chlorinated water-- the horseshoe crab I managed to get some spring water for which I added salt).
<They are very sensitive to water chemistry, unless the salt levels are at the appropriate level, 35PPM, pH, and composition (marine salt not table salt) then they will quickly die.>
He is literally surviving in a clear plastic storage tub over this weekend, and we attempted to dump some sardine in there and now a piece of chicken, as well as one of the dead hermit crabs.
<I would not try to feed him, more likely to just foul the water.>
There is no sand of which to speak and I have changed the water twice since then. We are hoping to get him back to the beach today but we are wondering if we will end up shocking the crab, as many marine animals get easily shocked by temperature changes.
<Getting him back to the beach is his best and probably only chance, a difficult species to keep even or dedicated hobbyists.>
I've put the crab out on the fire escape in the hope that the water will more closely match the outside (I realize this is unrealistic but I still feel it's better than my guesswork).
<Temperature is probably the least of his concerns to be honest.>
Since I am assuming he ate neither the sardine or the chicken, we are also wondering how long he can go without food, and have we inadvertently debilitated him too long to survive upon his return.
<He can go several days at least without food, best to just get him back to the ocean as quickly as possible.>
Re: Horseshoe crab, 8/10/09
Thank you very much for your advice. He was returned today, and very quickly burrowed himself into the sand of the wet shore, which I assume means he is healthy enough to recover speedily.
<A good sign.>

Horseshoe crab; taxidermy - 01/26/09  My granddaughter found a horseshoe crap <crab> fully intact on the beach at Clearwater FL..she would like to be able to preserve it for a school project..she would like to be able to keep it intact but is afraid it is going to start to smell...is there anything we can do to prevent that from happening... any help would be greatly appreciated..thank you!! Cheri <The horse shoe crabs I have prepared myself were more than 250 million years old, I used hammer and chisel. But, I have also tried to preserve dead aquarium crabs. On large crabs it is useful to cut the body open, remove the internal organs in order to avoid smell, stuff them with some man-made fibre wool that does not rot. Smaller crabs can be dried on a radiator as a whole without much smell. Another method to avoid smell is injecting 50% denatured alcohol and 50% dry preservative with a syringe prior to drying. Parts falling off during the drying process like legs have to be clued, e.g. with epoxy glue. After the drying process the specimens can be protected by clear lacquer, but only airbrush or other paint applied prior to the lacquer will keep them colored for many years. A internet search for "taxidermy crab technique" will bring up more ideas, there are actually many ways to do that, some easier, some for professionals, some incorporating more toxic substances like formalin. Cheers, Marco.> 

About Horseshoe Crabs  12/11/08 I understand that they need a large environment to survive, however my question is about the possibility of raising them in an aquarium to be released back into the oceans, and whether this would in some small way help populations. <Mmm... not wanting to encourage this sort of well-intentioned activity... Such efforts are not only almost always unsuccessful (the animals aren't "well-adapted" to wild living conditions, the root problems with the environment aren't solved thereby... And the hypocrisy of using other resources to favor some other species... Better to advocate longer term real fixes... Like our species getting out of the death business (more than a quarter of collective GDP is spent/wasted on "defense") and improving the life still here... including urging other humans not to reproduce... Really> I realize that they lay thousands upon thousands of eggs, but due to their rapid declines in numbers it would seem logical to assume that if many could be kept from predation, raised to a suitable size for survival, and then released, it could help their numbers. So here are the questions: 1. How large would a H.S.C. need to be to have a good chance of surviving (or how old/many moltings)? <... this information is available on the Net> 2. Would it be best to release them in warmer weather, and on beaches to avoid temperature shock? <It would likely be illegal to introduce any cultured animal thus... Please, don't do this> 3. Out of the four surviving species are any capable of survival in salinity deprived conditions (freshwater) or in Salt Lakes (such as the famous Salt Lake in Utah)? <Not as far as I'm aware... and again... not only is this an extremely poor idea in terms of likely success, ethos, but also likely criminal... Release NOTHING cultured or non-indigenous to ANY environment> 4. Are any found on the West Coast of the United States - as I have yet to find any material mentioning whether they are off the coast of California to Washington, and only one species is mentioned as being around the United State's East Coast and Gulf Coasts. <None on the west coast> 5. If any are on the West Coast would it be Carcinoscorpius rotundicauda, rather than the listed species of Limulus polyphemus in the Atlantic and Gulf - and if none are, could they be introduced to possibly help the other Horseshoe Crab species since they are already in the Pacific (same would apply for both Tachypleus tridentatus and Tachypleus gigas)? <Please...> Sorry for the many questions, but for years I have been fascinated with what is likely the oldest species living on the planet, <Not the oldest species...> unchanged and living since the rise of the Synapsids some 300 or more million years ago. Thanks! <I do want to encourage you to further consider, re-direct your efforts... What can we do to preserve what is here? Bob Fenner>

How to preserve a Horseshoe Crab 7/14/08 <Hi Bill> Please let me know. <If its a clean and dry shell, Id spray it with a few coats of clear Polyurethane (or similar lacquer-type product) in the sheen/finish of your choice. Just make sure you get the non-yellowing variety. If the crab still has soft tissue and is starting to decompose (as in extreme pew), Id find the nearest anthill and let the ants do the job. If you dont have an anthill nearby, just taking the carcass out into the backyard should be enough to bring in every ant, bug, and fly within a three mile radius. Together they should make fairly quick work of the crab. Unfortunately, the smell may also attract any number of varmints (domestic and otherwise), so keep that in mind. Another alternative method that I've heard people use involves burying the carcass and letting whatever assorted life forms/bugs that are in the soil do the job (but it could take a while). Either way, once all the tissue is gone, Id scrape/clean out the shell, let it dry completely, then spray it. I really have my fingers crossed for you that what you have is an already clean shell!> Bill Hurley <Take care and good luck! -Lynn>

Horseshoe crabs keep dying, 5/20/08 Hello. I purchased 27 horseshoe crabs at the end of April and am keeping them in a 270 liter tank with sand and water made from Instant Ocean. <Not nearly large enough for one crab, let alone 27.> Since purchasing, 13 have died. I feed them a diet of algae pellets and shrimp pellets with occasional frozen mysis shrimp. <Not appropriate food and likely indigestible by them.> The water temp is 74-76*F. <Too hot for most species.> The salinity is 25-30ppt. I haven't had any hits on the water quality and do water changes every other week. <Parameter numbers please.> The tank is filtered with 7 corner filters spaced evenly throughout the tank. Of the 13 that have died, at least 3 have had black book gills at time of death. Also, some have a white spot located near the compound eyes. I am not sure what it is or if it is harmful. I looked at my notes from my marine invert class but we looked at adults not juveniles so I have no clue of what it is. Is there anything you can think of that will save the rest of my horseshoes? <A very large, specialized tank.> I hate seeing them die and can't afford to have them die since I am studying them for my thesis. I can attach pictures if necessary but I'd have to resize them and don't have access to them from this computer. Thanks for your time. Whitney <Please see here for more on these crabs, they have very specialized needs and do poorly in captivity. http://www.wetwebmedia.com/hshoecrabsart.htm .> <Chris>

Re: horseshoe crabs keep dying, 5/20/08 I am moving them to a 2000L tank with sand and real seawater. Do you think that will help? <As stated in the article linked in the previous e-mail, it will help, each crab needs about 10 square feet to feed from.> As far as the food goes, the company I purchased them from feeds them algae pellets and they apparently do fine. Why are shrimp pellets and frozen shrimp not appropriate food and how does it make it indigestible? They seem love it and its always gone in a few minutes and they're pooping it out so obviously they're digesting it. <Also posted in the article, mostly eat small crustaceans from the sand, and have mouth parts appropriate for this, not larger shrimp pellets and algae wafers. Takes most about 1 year to stave in captivity, so difficult to determine what they are actually eating.> The water temperature is the temperature of the water right now in Florida. They crabs came from Florida so they're use to it but what do you suggest it being? <Most species prefer cooler water, and are just temporary visitors to the warmer parts.> When you say "a very large specialized tank" what do you mean? I know specialized for horseshoes but what should it include? <Lots of live sand, DSB, little rockwork to get in their way, also listed in the article.> Thanks for your time. Whitney <Please read here http://www.wetwebmedia.com/hshoecrabsart.htm > <Chris>

Preserving a Horseshoe Crab Shell - 4-11-08 Hello. I recently found a horseshoe crab shell. When I found it in our barn, it was filled with dust , dirt and some cobwebs. I rinsed it off with some cool water and set it out to dry. Now it is completely dry and looks very dull. How is the best way to care for the shell. I think that it will make a great addition to my sea shell collection and would love to preserve it. Thank you. Carolyn <Mmm, once you get it very clean and dry, I'd "spray lacquer" it... Do see the paint area in a good-sized hardware store, or a paint store period... re various finishes/reflectivities... I'd go with something with a low sheen... make a "box" of sorts to keep down errant spray, and apply in a few coats/passes outdoors on a nice day. Bob Fenner>

Horseshoe Crab: Feeding Frequency -12/17/2007 Hey Guys, Quick question, I have a 2 inch horseshoe crab. How often do you think I should directly feed him with meaty foods (ex: krill, Mysis, carnivore preparations)? Thanks!!! <Hmmm... how often does one feed a giant prehistoric predatory marine arthropod? Good question. I presume it will feed as it wishes (as much as it can find - both on the food you try to give it and on your benthic critter populations) despite whatever schedule you try to put it on. In any case, what will you do with this beautiful creature once it's the size of a small cat? Best,
Sara M.>

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