Urchins

[juniormmm]

I have a ton of corraline on my back wall. I also have patches of hair algae throughout my 29g as well as this red wire type algae that is extremely tough and embeds itself into the rock. I tried to pluck the strands out with tweezers but they do not come out. It almost looks like a red brillo pad. Would the pencil urchin eat any of these? Also, which would they prefer? Meaning would they ignore the corraline and eat the hair algae 1st or vice versa?

[jeremai]

ime, coralline, then film algaes, then turf algaes. depends on the urchin of course, but I've never seen them mow down long strands of anything.

[ajmckay]

+1 to jeremai. If there's enough calcareous algae (coralline) they probably won't go after anything else.

 

Also, I believe pencil urchins aren't reef safe... They will eat corals, shrimp, and any fish it can catch (sleeping).

 

http://www.reefkeeping.com/issues/2003-11/rs/index.php

[johnmaloney]

i think there is some confusion with pencil urchins (mine urchins, slate etc...) There are more than one species of "pencil urchin", and that causes problems. One of the species from the Pacific eats corals, and it appears on the first page of a google search, so there is this new Internet belief that all pencil urchins eat coral. As with most things in this hobby though it depends on species, and the Carribean species do not eat coral. THey will eat smaller LR organisms, sponges, tunicates etc...but most people don't have them successfully for long anyway. As far as an urchin catching your fish or shrimp, it would have to be dead first, no pencil urchin is going to catch a moving meal, sleeping or not. It has no choice but to but into with its spines first. I think if there are any horror stories they probably start out like "I came home to find such and such dead and my urchin eating him, he must have killed my such and such". I hear a lot about how the nassarius snail killed such and such a fish before. In these cases it is far more likely that the snail/urchin was performing its scavenger job, rather than taking down fish. With an urchin, your greatest concern will be acrylic scratching, bulldozing and wearing frags and hermits as camoflauge. The pencil urchin can only really scratch acrylic and and bulldoze.

 

That said, we feed the urchins codium in the winter, gracilaria in the summer and filamentous green species when we can get the "surer" species in stock. They mow just fine IME. Jeremai, have you had long hair algae in your tank? What kind of urchin?

 

juniormn - what kind of red wire algae? like a gelidiopsis? (excuse the spelling) Pencils eat gelidiopsis sp., as do rock boring urchins. They would probably prefer the coralline and hair algae, but urchins aren't so picky as to leave one meal in search for something tastier down the road. Slow and blind doesn't lead itself to much of a nomad lifestyle. I think a lot of it has to do with initial placement in the tank and what they just find themselves on.

 

Urchins, like turbos are one of those items I would only add as a last resort, there bulldozing lifestyle isn't great for aquaria. Try some emeralds for the "red wire algae", and manual cleaning of the GHA on the glass, (it is easy enough on the glass, just twirl it up on a toothbrush), or the addition of a turbo. this might give you an alternative to urchins.

[juniormmm]

This is what it sort of looks like. Really tough and doesn't break off the rock. Stays in a small bunch that almost reminds me of a brillo pad. It doesn't grow tall, it stays close to the rock and grows very thick. The individual strands stay thin(thinner than chaeto) but the colony grows thick like a bush. Its good to hear that there is an urchin that will graze on some of my algae.

 

How fast of an eater are these Caribbean Pencil Urchins? My walls are covered with coraline and I have a few smaller patches of that red wire stuff along with the hair algae. What are the chances that 1 urchin in my 29g would strip itself of all it's food?

 

Thanks for your help

[johnmaloney]

in a 29? it would run out of food at some point. They get pretty big and live a long life for a cleaner. At some point it would run out of food...I guess it depends on how quickly new food grows. The differences you mention though are enough not only to put the algae as a different species as pictured, but possibly a different genus.

 

i have seen a single (adult) pencil urchin take down a 4x3x5 piece of gracilaria in an afternoon. It pooed most of it out, but what can you do?

 

are the red wire tufts accessible? have you tried peeling it off, or dental picking? (I know how difficult the short red algae can be to remove, just trying to see if a different method helps. Usually plucking gets you no where, they are hard to say the least.)

[Urchinhead]

+1 to What John said with the addition that Tux's will also go after hair and I have found it best to "trim" it down to a more manageable length as well as put the urchin in the path of the algae. When it runs out of food you can supplement with Nori aka seaweed used to wrap sushi rolls. Cheaper than trying to track down various forms of algae.

[johnmaloney]

tuxedos are cool, they look awesome for sure. they have more of a "wear things as camo" tendency then I like, but I am still recovering from an incident that happened 6 years ago with a variegated pincushion wearing almost everything I had in my tank at the time, so take it with a grain of salt.

[Urchinhead]

Oh yes! I had mine walk a zoa colony (went from a few heads to about 20) all around the tank! It would also grab the odd hermit which was always fun to watch. Hermit would have to exit shell, pull shell off of Urchin, re-enter shell and it took the hermit a while to figure this out. They don't get too big which makes them good for Nano's and have about the same destructive/bulldozer effect as a turbo so its a good alternative in my book.

[johnmaloney]

hah! at least your hermit was smart enough for that. I have some rock boring in a tank with hermits and the few that are rounded up just kind of try to kick out of the urchins clutches to no avail. i guess the micro sized hermits haven't learned all the trick yet. they get dropped eventually though.

[juniormmm]

I would LOVE a blue tux, but I would end up throwing it out the window after it messed with my zoas. So that's a no go. I was thinking about getting a lawnmower blennie, but their diet isn't as broad as the urchins, and I really don't want to add anymore fish. I would love to have an urchin not only for some of the algae, but also to give my tank some variety. I have no problem with them getting bigger as I would just transfer it to a bigger tank.

 

Somebody told me to look up a pincushion urchin. Does anybody know anything about those? Would it be better than the pencil urchin?

 

And as for the red wire algae...I cannot pluck it. The tweezers just can't get a strong enough grip without cutting the strand. It is not in a mat so peeling would not work. The only way I've been able to remove any was to use a pair of bone cutters and shave off the 1st few millimeters of the rock. I've gotten most of it out but there are some spots on the backside of my rockwork that I cannot get to with any tools due to my tank's height and depth of the tank. I'm just not able to get my arm far enough down into the tank to get at it.

 

As for the pencil urchins. Is there a way to tell if one is from the Pacific or the Carribean? I don't trust my LFS with specific info on species. And if I saw some pencils in a store I would wanna know whether for sure if it is reef safe.

[juniormmm]

So after looking up some more info I ran into Echinometra lacunter (Rock Boring Urchin). John do you have any info on these. I read that they tend to not be "bulldosers" and that they stay relatively small. Would they work for macro algaes? Do they have any drawbacks besides their sharp spines?

[johnmaloney]

you want this guy: (Eucidaris tribuloides)

http://reefcleaners.org/components/com_vir...b742cd532df.jpg

 

and i think not this guy:

http://www.reefs.org/library/aquarium_net/...ages/urchin.jpg

 

the urchins has a "ma" something in the species name I think....I will look it up. [Edit] I think it is Heterocentrotus mammillatus. There are a lot of "pencil/slate/club" urchins in the pacific, so you may want to double check it, but that is what I am thinking.

 

 

Rock boring urchins eat a ton of food, and they have the "bee sting" spines which are very sharp. You can still handle them if you are delicate though and not all clumsy about it. Eats coralline, scratches acrylic and wears things as camo. Not as bad as a tuxedo about it, and certainly not as bad as a regular (variegated) pincushion, but they do camo themselves all the same. They get pretty big, spines included about the size of a softball. They usually are small in the trade though because they tend to be inexpensive and transport of a larger specimen costs monies. The wholesaler's tend to send out golfball sized specimens, but they can grow to a decent size. The same thing happens with imported long spines. They easily grow to volley ball size, but you usually see them baseball size. Queen conchs are the same way. In a 29 gallon any of the urchins, (pencil or rock boring), would end up needing to be fed, and then eventually moved from the tank. Just give it back to the pet store.