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Finally got my PPC Urchin to eat

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I was noticing my new angel picking at everything the other day, so I figured ,perhaps I should keep him better fed to leave the corals alone. I put a small slice of romain lettuce in there from the dinner I was making that night to see if he would eat that instead. He was afraid of it and wanted nothing to do with it.


Then I forgot about it.


I came home last night and noticed it was all gone except for a small piece that was out of the water. Then I noticed the urchin was right up at the top as far out of the water as he could go trying to get to the last piece of lettuce. He was completely upside down with his mouth out of the water trying to reach it.


I took the lettuce off the clip (it was just clothes pinned to the tank rim) and set it on top of his mouth. immediately he clung to it and the lettuce made it's way to his mouth where he sat happily at the top of the tank eating it for the next hour.


I've not actually seen him eat up until now, the only thing he was feeding on in almost a year (as far as I know) was the coralline algae. He always seemed to refuse the nori I put in there in various places (tied to a rock ,placed him on it, I tried everything).


So, I am happy to say that it looks like these strange critters will eat romain lettuce.

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Might not be very good for it... Lettuce is mostly water(freshwater), and as well unless it's organic it might have several nasty chemicals sprayed on it.


::edit:: If you want to experiment a bit, I've seen several health food stores carrying a number of different seaweed varieties.


Actually, if I can get out today I might jot down the names for researching...

Edited by carbon-mantis

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Try feeding him dried seaweed or Nori. Be sure to get the unroasted unsalted kind. You can find it pretty cheep in most healthfood stores. Feed about a 1x1 inch square once a week and he'll be a happy urchin.

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Sigh. I have to bug CM about getting this either stickied or posted in the articles section...


Sea Urchins


Scientific Information:


Phylum: Echinodermata

Class: Echinoidea

Order: Multiple. See below


Common Names:

Pin Cushion, Tuxedo, Long Spine(v), Short Spine, Pencil(sn), Flower(vv), Fire(vv), Sand Dollar(sn)


v = venomous

vv = very venomous

sn = special needs



Pin Cushion - Caribbean

Tuxedo - Indo-Pacific

Long Spine - Indo-Pacific

Short Spine - Indo-Pacific

Pencil - Indo-Pacific



This article is divided into four sections. General Information, Reef Safe Urchins, Special Needs Urchins, and Urchins to avoid. General Information contains general notes on husbandry while the other sections deal with specific species broken out by type of urchin and contains specific details on tank size, diet requirements, special needs, and the like.


General Information:

There are about eight different kinds of urchin, including the sand dollar, sold in the trade. Their habitats range from the Atlantic to the Indo-Pacific and Caribbean. Most urchins are reef safe with the notable exception of the Pencil Urchin which is carnivorous and will eat corals as well as fish and the very pretty but very venomous flower and fire urchins.


Urchins tend to be some of the more unusual and potentially entertaining additions to a cleanup crew and actually cut down substantially on the required number and diversity of said crew. In general one urchin can handle the job of several glass cleaning snails and several rock cleaning snails and hermits. They are no harder than other invertebrates, like crabs and hermits, to keep and do a good job relative to their size of keeping control of algae. While urchins tend to be nocturnal, many will come out during daylight hours.


The best Urchin for Nano tanks are the Tuxedo's as they remain relatively small while still providing entertainment and high cleaning to relative size value. Watching them work is interesting especially when they are on the glass and their mouth can be seen in operation. They will eat all kinds of algae including diatoms, green hair, etc and there is anecdotal evidence of them eating cyno as well.


There are three downsides to having an urchin in the tank. If the urchin selected is a Pinchushion or Tuxedo and there are small loose bits of rock, small bits of coral or frags, or hermits and snails in the tank the Urchin may take them for a free ride around the tank on its back. The reason for this is that this subspecies uses shells and loose strata as tactile and visual camouflage from their natural predators. Urchins are also very strong for their size and can inadvertently topple corals and/or rocks as they move about the tank. The caution used when putting a turbo snail into a tank would be the same for an urchin. Make sure the rocks and corals are stable and not easy to move. Finally, urchins eat all kinds of algae including coraline.



Urchins are not recommended in a tank that contains any:




some types of larger wrasse








parrot fish



as urchins are a natural prey of these animals.



Most Urchins are either herbivores or omnivores with the notable exception of the Pencil Urchin which is carnivorous. Urchins will eat all forms of micro-algae from all surfaces including rock work, glass, and substrate.


If algae is not prolific in the tank it is best to supplementally feed urchins with some form of sea weed such as Nori. A 2"x2" sheet about once every week or so should be sufficient.


Feeding can be handled in one of two ways. First, hang it on the glass or rock where they will find it. Second, hand feed them. If hand feeding the urchin will do something called an "urchin kiss" where their spines will gently grasp the tip of your finger as their sensory tentacles explore if you are worth eating. Press the sea weed gently on the spine or place it in the urchin's path and allow it to roll up on it. Both need to be done when the urchin has its feeder tentacles extended. they look like little sweeper things about the diameter of a human hair.


Acclimation Process:

Gradual. If the delta between the salinity level they are used to and your tank is too high they can get salinity shock. An example acclimation method would be to place the urchin in a bucket or container with the water it came with, a heater, and a very small power head. Over a 30 to 40 minute period remove 4 oz of old water and replace it with 4 oz of water from your tank repeating every 7-10 minutes for about 30-40 minutes. (Note this assumes you have more than 12 oz of original water and that the original water is not fouled or contaminated. Drip method would be best if you do not have at least 12 oz of original water)


Things to watch out for:

If an urchin's spines fall off they are most likely dying and there isn't much that can be done to save them. While it is possible to attempt rehabilitation via a hospital tank coupled with offering allot of food like nori usually by the time the spines are falling off it is too late and humane euthanization such as via freezing is more appropriate. It is important to remove the urchin from the tank as soon as spine loss is observed as delay could cause the urchin to expire in a location difficult to access or see which would cause a spike in the tank.


As with all invertebrates copper based medications are fatal to urchins.


Urchins are also sensitive to rapid shifts in salinity and can get salinity shock which can be fatal.


Urchins do not tolerate high nitrates. If there are high nitrates in the tank an urchin will shed its spines.


Wound treatment from an urchin stick:

Spine sticks from urchins can be quite painful and in the case of flowerpot or fire urchins or with people who have allergies fatal. Prompt treatment is important to reduce pain and swelling as well as the risk of infection.


If stuck by a flame or flowerpot urchin, if you have a allergy, or feel unwell or concerned seek appropriate treatment immediately from a medical professional.


If stuck by an urchin spine remove the spines as quickly as possible. You will not get all of the spine and this will hurt but it is important to remove them quickly to minimize pain. Do not dig out the spine as this can do more damage and cause higher risk than leaving it in and allowing it to work its way out. Next soak the affected area with vinegar followed by a hot water soak at the highest temperature you can stand followed again by a vinegar soak. This should minimize the pain and swelling/stiffness associated with an urchin stick.


Reef Safe Urchins:


Common Name: Long Spine(v)

Scientific Name: Diadema

Max size: 8+ Inches

Tank size: 50 gallon+

Food: All kinds of algae

Reef safe: Yes if well fed


Spines are venomous and getting stuck hurts allot so handle with care

The spines can puncture some corals

Very good for controlling filamentous algae including hair algae


Common Name: Short Spine/Rock

Scientific Name: Echinometra

Max size: 3 Inches

Tank size: 30 gallon+

Food: All kinds of algae

Reef safe: Yes if well fed


Very good at controlling hair algae


Common Name: Tuxedo (blue or black)

Scientific Name: Mespillia Globulus

Max size: 2 Inches

Tank size: 15 gallon+ (with feeding)

Food: All kinds of algae

Reef safe: Yes if well fed


Will pick up debris/shells/rocks/etc as camouflage. If it isn't then it may be sick or dying

May need supplemental feeding with nori if in 30+ gallon tank and will need supplemental feeding if in smaller tank


Common Name: Pin Chushion

Scientific Name: Lytechinus Vaniegatus

Max size: 8 Inches

Tank size: 30 gallon+ when small 75 gallon+ when over 5 Inches

Reef safe: Yes

Food: All kinds of algae


Will pick up debris/shells/rocks/etc as camouflage. If it isn't then it may be sick or dying

May need supplemental feeding with nori


Special Needs Urchins

(need special conditions or will eat your coral and fish)


Common Name: Sand Dollar

Scientific Name: Clypeaster, Encope, Mellita

Max size: 6 Inches

Tank size: 30 gallon+

Food: All kinds of algae, bacteria, and diatoms

Reef safe: Yes


Needs a deep sandbed 4"+

may suffocate in fine sand/mud

Verify origin before purchase as cold water species will die in reef temp tanks

This is a hard to keep species so be aware of that before purchase


Common Name: Pencil

Scientific Name: Eucidaris Tribuloides & Heterocentrotus Mammillatus

Max size: 6 Inches for ET & 13 Inches for HM

Tank size: 100 gallon+

Food: Omnivorous but trends towards carnivorous

Reef safe: No


Will eat sessile(corals) animals and will try to catch mobile ones as well

Good for a species specific tank with lots of room


Urchins to avoid unless you know what you are getting into and are comfortable with the risks:


Common Name: Flower (vv)

Scientific Name: Toxopneustes

Max size: 6 Inches

Tank size: 100 gallon+

Food: All kinds of algae but needs occasional meat feedings

Reef safe: yes if well fed




May need supplemental feeding with nori


Common Name: Fire (vv)

Scientific Name: Asthenosoma

Max size: 6 Inches

Tank size: 100 gallon+

Food: All kinds of algae

Reef safe: Yes if well fed



May need supplemental feeding with nori

Edited by Urchinhead

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1 - he doesn't touch the various Nori's I've offered him. But the health food store seaweed idea is pretty good actually. I might look into that.


2 - Thanks urchinhead, but you've already posted that to me multiple times in the last year whenever I make a comment on my urchin LOL. It's helped tremendously though last year when I got the little guy. I agree it does need to be a sticky ;)


I've had him almost a year now and he's provided many entertaining moments for us :)

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