Urchin Hitchhiker: Pencil Urchin - 1/31/08
Hello Crew!
<Hi Andy!>
About 4 weeks ago, I purchased a large piece of cured Fiji rock to round out my LR aquascape. It is a neat piece, with a big, winding hole running the length of the piece. Even though my LFS claims that the water in the LR tanks are not mixed with other water, I have seen fish in the tanks from time to time, so I placed the LR in my 30
gallon QT for 2 weeks just to be on the safe side. During QT, I can't say that I stared at the LR much other than when checking water parameters, etc. After the QT period, I placed the LR in my tank. About 2 days later, I was shining a flashlight into my tank to check out the nighttime goings on. When I shined the light in the hole of the new piece of LR, I noticed an urchin that is about 2" in diameter (body) (thankfully, the lack of acclimation--twice--didn't kill it!). From browsing WWM, I can confidently tell you that it's some type of pencil urchin, either a Eucidaris tribuloides or a Heterocentrotus mamillatus (my guess, since the LR is pacific, but it has characteristics of the
former).
<Okay>
It is very elusive, so I haven't been able to get a picture of it (or even a good look at it). In fact, for about a week (and apparently, the entire time it was in QT) it didn't move from the cave. Since then, it has made an appearance outside the cave, but only briefly and then on the underside of this same piece of LR. It has now moved back into the cave (who knows where it goes at night).
<It goes out to eat! These urchins are nocturnal foragers that, once they’ve found a nice little protected spot, tend to use it as their “home base”. They wedge themselves into place during the day with the help of their thick spines.>
My research leads me to believe that it likely poses little risk to its other tank mates--a Sailfin tang, a Gold Stripe Maroon Clown, a Brown Combtooth Blenny, a Royal Gramma, a Copperband Butterfly, 2 cleaner shrimps, 15 or so mushrooms, some type of tree coral (I keep meaning to send in a pic for an ID), a Lemnalia tree coral, two small colonies of pulsing Xenia, and a Trachyphyllia geoffroyi. My tank is 110 gallons, with about 90
lbs of LR, under-the-cabinet trickle filter (in which I run activated carbon that I change out every 2 weeks), a 30 gallon fuge (LR, a huge tuft of Chaeto, and 5" DSB (with about 1 billion bristle/fire worms) on a reverse daylight cycle), and a Coral Life Super Skimmer. My water parameters are: ammonia, nitrite, nitrate and phosphate all 0, temp
80*F, alk is 3.5 meq/L, pH is 8.3, calcium is 400, and spg is 1.026 (I have a Salifert I2 test kit and a SeaChem iodine test kit, both of which show no appreciable levels, even after dosing with Kent Iodine over a period of days--I've since stopped adding Iodine until I can figure this out).
<Good thinking. Please read over the FAQ’s here at WWM, starting here:
http://www.wetwebmedia.com/iodfaqs.htm >
I use RO/DI water (mixed/circulated days in advance of water changes).
<Excellent>
I dose, as needed, with ESV B-Ionic 2-part buffer. Probably more than you need to know, but . . .
<Hey, it’s better to have too much information in these queries than too little!>
So, to my questions . . . I'm a little worried about this guy starving, because he doesn't seem to move around much and there's not much on the new piece of LR to feast on.
<Hmmmm, well he’s undoubtedly moving about at night to feed. That’s typical for these urchins. What we don’t know is which species it is. Some are mostly herbivorous, while others dine on corals, sponges, tunicates, bryozoans, snails, etc. Some even employ those spines to trap/kill fish, shrimp, and other organisms.>
I have tons of coralline algae (too much), but the urchin doesn't seem interested in finding it. An attempt to plant Nori would meet with immediate failure, as the Sailfin Tang and Blenny would make quick work of it.
<Well, the good news is that these fish aren't nocturnal. I'd rubberband some Nori, or a seaweed sheet, to a rock and place it near the cave after the lights go out.>
I have shrimp pellets that I use to feed my fuge--should I try dropping some of those in the display at night?
<You could certainly give this, or a bit of clam/squid/etc a try. It’s going to be tough though, to keep the shrimp and/or any other nighttime critters from running off with it. To get around this, try to put the food as close to the urchin as you can, and give the shrimp their own little bits to distract them.
Is it normal for these urchins to remain fairly stationary?
<During the day, yes, very normal.>
I would think not. Also, am I correct that the urchin poses little risk to my sessile inverts?
<Again, depends on the species/individual. These urchins are generally not considered reef safe. Not only because they can be predatory, but because they tend to bump into things with resulting damage to corals and sometimes your carefully arranged aquascape! For more information/photos on this family of urchins, please see these WWM links:
http://www.wetwebmedia.com/urchinsii.htm
http://www.wetwebmedia.com/urchinfdgfaqs.htm >
Thanks for the help/info.
Andy
<You're very welcome, Andy. Take care. -Lynn

Purple Spined Sea Urchin... Arbacia punctulata   7/30/07
Hi Crew.
<Hi Rick, Mich here.>
I was walking the beach in Florida the other day on the Gulf of Mexico side and found a purple spined sea urchin.
<Lucky you... the walking on the beach part... I seem to be good at finding urchins with my feet! Ouch!>
I did a web search on them and they are, according to them Arbacia punctulata- purple spined sea urchin.
<Is endemic to Florida, and generally live on rocky bottoms as opposed to sandy bottoms.>
I was thinking about putting him in my FOWLR tank. Is he safe?
<Mmm, I doubt that you will be able to provide suitable nutrition for him. These animals typically eat sessile invertebrates which he will likely consume your current tank population quite quickly. Gut content analyses have show bryozoans, hydroids, barnacles and tunicates and limited algae. The algae are typically only those growing on the rubble. but the diet is usually more heavily weighted with animal matter>
I have a coral shrimp and a tang. goby and clown. Right now I have him in my QT tank. Would he benefit my tank?
<I don't think the tank would benefit nor do I think it the urchin would benefit. I think it would be best to return him to where he was found.>
I also found some large hermit crabs, about 2 1/2 inches and was wondering if these would be good substrate cleaners?
<A big no go there! Usually any large hermit crabs are highly predatory, capable of killing fish and even well protected animals such as urchins.>
Those I didn't bring home
<Wise.>
but the urchin was too pretty to pass up and they do sell them locally.
<I do not have personal experience with this species, but from what I have read, I obviously have concerns, perhaps those in your local market may be able to guide you better, but with the information I found describing the typical diets of these urchins, I would be concerned about starvation.
More here: http://www.int-res.com/articles/meps2005/295/m295p171.pdf >
Thanks for all info past and present you guys are great and make my hobby so much easier. Rick
<You're welcome and thank you for the kind words. Mich>

Urchin foods 7/15/05
What is the diet (what do they eat) of an Asthenosoma ijimai, Diadema  
paucispinum, Asthenosoma Varium and a Astropyga radia
<Please see Baensch Marine Atlas, Marine Invertebrates v.2. Bob Fenner>

Hungry Urchin? (11/21/04)
Hi <Hello. Steve Allen with you tonight.>
I've been reading your brilliant Marine section for months & wonder if you can help with an urgent problem. Our reef tank is about 6 months old. One of our early purchases was a lovely little black spiny sea urchin. He helped clean up the tank as it cycled & settled down. We have very little "nuisance" algae now & are beginning to wonder is "Spike" is hungry... <I'm not sure if they get "hungry" per se, but rather they eat anything the deem edible that is in their path. The pretty much eat all the time.> Two nights ago he ate our small but healthy pulsing xenia, last night he had a go at the Gorgonia. <Did you see it eat these or are you guessing?> We always have seaweed in the tank for him, the Mithrax crabs & the tangs (& most of the other fish who also seem to eat it) which he seems quite happy with in the day but obviously gets bored with at night. We have only recently started putting soft corals in the tank although have had green star polyps in the tank for about 4 months - he's shown no interest in that! We think we're going to have to take him back to the LFS unless you can suggest any other solution.
Any advice welcome. <If the urchin is eating these desirable organisms, your only option is to take it back. There is no way to compel or persuade it not to.> Thanks, Mandy Thomas <Good luck.>

Lobophora (Brown Wafer Algae) Eating Urchins
Trying not to bother you guys, but time to go to the experts.
<MikeD here and not an expert, but a long time urchin aficionado>
75G FOWLR
DAS H99 in-tank sump/skimmer
Lights - 2x40W NO (today replaced 9 month old 50/50, and 11 month old full spectrum with Coralife 50/50 and 10000K)<It was time>
NO2/NO3 0.0
pH 8.1
Believe I have the nutrients under control, using RO/DI and have a good size patch of Halimeda that I crop.<Sounds good>
Lobophora is taking over my tank. After agonizing over what urchin to get, settled on a Blue Tuxedo after seeing a monster size Long Spine.
Well, after watching the Blue Tux eat coralline for a week and going out of it's way to not even touch the Lobophora, it's now decided to spite me by packing around pieces of it.<It's not spiting you, but rather, like many short-spined urchins, camouflaging itself to escape notice of fish predators, such as triggerfish.>
Talked to the LFS and they are willing to exchange for a Diadema.
Diadema questions:
-how realistic a Diadema will eat Lobophora?<It depends on whether it is obtainable or growing on irregular surfaces that the urchin can't easily adhere to.  Flat, open surfaces will almost always be preferentially grazed due to the ease with which the tube feet can hang on.  Many will learn to go to the surface of the water to be hand fed, should you so desire.>
-they're ~5" diameter now, how big, how fast?<This depends upon available food within reach, the type of food and the water chemistry.  Urchins were long used as "miner's canaries" to monitor water parameters before the advent of cheap, easy, reliable test kits, proceeding to shed their spines as water conditions deteriorate long before most fish show adverse reactions.>
-how does a Long Spine's appetite for coralline compare to a Blue Tux?<Again, it depends upon what's easiest to reach, although if it helps any, the Long Spine's aren't usually camouflagers.>
-can they be exposed to air (transferring to quarantine)? For short periods. The waste discharge hole (anus) in the top usually prevents trapped air bubbles.>
-if the Long Spines a bust, how do I handle the Lobophora?< Pruning with tweezers and shears is what I usually resort to.  Foxfaces will usually remove ALL vegetation to an extent that makes most tangs look like carnivores.>
Mark in snowy Edmonton, Alberta,<Brrrrrrrr>

Urchin Question (10/4/04)
Hello! <Hi! Steve Allen with you tonight.> I have a question about a purple urchin. <Do you know the scientific name, purple is a rather common color among urchins.> I recently got him and he used to cruise all over the tank. Now I notice he keeps falling off the walls and he ends up upside down then I have a hard time getting him latched on again. <this is worrisome. They usually adhere firmly.> I have to prop him up but his spines keep him from being flush with the tank on the underside. Is he sick? I am thinking he's malnourished cause I don't feed him anything separate. I feed flake food and frozen krill and I also have some type of algae in the tank that floats around and is also starting to attach to a rock I have. <Do you have coralline? Urchins eat algae off of rocks.> Is this enough food? <Most urchins eat detritus and usually do not require supplemental feeding unless the tank is incredibly clean.> I read that you suggest that stuff from the oriental food place, is there anything else that I can buy in a regular store? <I'm a big fan of Sea Veggies for tangs and other herbivores. Spirulina wafers might work.> Thank you for your help. My urchin will be grateful!!! <Hope this helps. You can try these feeding options, but I'd also recommend checking all of your water parameters and making sure that you keep steady, ocean water chemistry. Echinoderms to best with pH and SG at normal seawater values and very stable.>