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.>