Give or trade for the EWOF meeting.

[Ben]

Maybe some of our leaders would rather raffle these, but I'm trying to judge interest.
- 1 large or 2 smaller frags of finger leather / colt coral.
- Several Xenia frags.
- Several Green star polyp frags.
- Urchins.

I have (at last count) 18 Echinometra mathaei sea urchins in my 45 gallon tank. The tank is just not big enough to support that many adult urchins, so I'd like to give 6-12 away if I can manage to unstick them from surfaces at night.

They are the most common sea urchin in and around Hawaii and much of the Indo-Pacific and usually grow to 2.5" in diameter but they've been seen as big as 6" in diameter. Mine are mostly 1.5" to 2" in diameter. They eat all of the algae they find in my tank and don't seem to hurt anything else. They burrow into the live rock for the day and come out at night to forage. Once one picks a home, it generally goes back to that spot every day and makes the hole bigger as it grows, unless another urchin kicks it out. Since mine were live rock hitchhikers, they all slowly kicked each other out of the original rock. There doesn't seem to be any algae they won't eat in my tank except bubble algae and cyano/red slime. I don't know yet if they are eating the Chaeto I won in the raffle, but they probably are.

They are well suited for life in a tank with animals that might eat snails or hermit crabs. There are warnings that they sometimes eat soft corals, but I have never seen them touch any of mine, so that might be only if they run out of algae to eat. As far as I can tell they are completely reef safe so far and don't bother anybody except the turbo snails when one decides to clean the algae off the snail's shell.

For more info, look here: http://www.reefkeeping.com/issues/2003-11/rs/index.php

[MedicineMan]

Do you have any pics? I'm wondering if these are the little guys I see sunk into live rock with just their spines sticking out.

[oyam123]

Its good to give....

[Ben]

Originally Posted by MedicineMan

Do you have any pics? I'm wondering if these are the little guys I see sunk into live rock with just their spines sticking out.

Yeah, that's how mine usually look during the day. The white rings at the base of the spines is what makes them easy to identify as it is distinctive of this species and it's close cousins. There's a pic of one embedded in my post above. Click on: Echinometra mathei

[StellaMN]

Ben...I'd love one or two of the urchins. I'm willing to try anything to battle my bryopsis problem.

If I get a chance to do some fragging in the next couple of weeks, I should have a few things, too.

Jodi

[mjsandbe]

I am interested in the urchins. I would love a picture but am willing to try it out sight unseen on your word that they are 'good kids'

[mjsandbe]

Are they as sharp as they look. I would not want to impail myself while working in the tank.

[Ben]

Here's the picture I had linked above.


This is pretty much exactly what they look like. About 1" - 2.5" from spine tip to spine tip. The spines come in rose, pale tan, and similar colors, but the bodies are generally black or close to black and they have white rings at the base of the spines. They are spiky, but I've never gotten pricked by one because I wear gloves in the tank. They don't have poison glands on their spines like some other varieties of urchins, nor are their spines designed to stab you, break off and cause an infection like long-spined urchins. These ones use the spines for movement and a motionless defense. They hide in the rock as the rest of their defense. That's why taking pictures is often difficult.

But it's lots of fun to turn the lights on late at night and see them all cruising around looking for algae.

[MedicineMan]

Originally Posted by Ben

Yeah, that's how mine usually look during the day. The white rings at the base of the spines is what makes them easy to identify as it is distinctive of this species and it's close cousins. There's a pic of one embedded in my post above. Click on: Echinometra mathei

That's not the one I was thinking of though I see plenty of these, too. I looked to see if I had a pic but I don't. The ones I'm thinking of have a more "delicate" spine but are not the long spined urchins I see all the time, either. (Speaking of long spined urchins, did you know that at 60 feet under water blood looks black?)

[Ben]

Here's how they might look on the reef:


And here is it's common cousin, Echinometra oblonga:



Here's a site with a lot of urchin pictures, mostly from Hawaii:
http://www.marinelifephotography.com...ns/urchins.htm

[StellaMN]

Ben---what are the chances of me getting one or two of the urchins before the next meeting??? I'd really like to get this bryopsis issue under control.

Thanks!

Jodi

[oyam123]

what is bryopsis

[StellaMN]

Industrial strength hair algae....

It looks like hair algae, but cements itself to the rock....when you do manage to pull out a chunk, it feels similar to steel wool.

I got in my tank from some corals that I rescued....and when I was sick this winter, I topped off with non-RO water and it has really taken off. I'd post a pic, but I'm too embarrassed.

J.

[Ben]

Note: The urchins do not appear to seek out and eat bryopsis by choice. They just eat it when there is tasty coraline is next to it. It there is no coraline, they ignore it. In the back of the tank, where not as as much light reaches, the bryopsis is unharmed because there isn't as much coraline to eat.

Some pics from my tank:

[Ben]

Jodi,

Just email me some times when you could drop by. I'll pick what works best for me and send you directions. The urchins also do not seem to eat bryopsis surrounded by soft corals, so it looks like part of the decline of bryopsis in my tank is just buttons and GSPs overgrowing it.

When I looked in the middle of the night again last night, I counted 3 Echinometra oblonga, maybe about 10 Echinometra mathei (next to the powerhead in the pictures above), and 4-5 that might be mathei or might be a third species (the one burrowed into the rock in the picture above). Their spines were shorter, blunter and darker than most of the mathei's but otherwise they looked pretty much the same and the one I got the best look at had the white circles. The oblongas are much smaller and have black spines along with a black body.