in-tank urchin reproduction?

[914]

So... This small black urchin, about 1/3" across arrived on some cultured FL LR. Since then, it's grown to about 1.25", in about 4 months. Cruises around the tank (29, about 40# LR, FL and Fiji) eating stuff, leaving 'pretty' white stripes all over the rock.

Being one who appreciates biodiversity, and having a kindly bent towards hitchhikers, i'm quite happy with this.

But....... today i noticed another baby urchin.. this one is about 1/4" across, and looks just like "momma" (i'm guessing about the momma part) did when she was that size....

knowing that urchin reproduce by eggs (roe), i'm worried that i'm about to have an urchin population explosion.

The question is: what's the gestation period for urchins? What can i do with 50 (500?) baby urchins?

The ones in my tank look like a cross between a long-spine urchin (http://www.fishsupply.com/images/Products/CUA00.JPG) :

and a pincushion urchin (http://www.premiumaquatics.com/livestock/pincushion.jpg)

They're all black, and the spines are longer than the pincushion, but shorter than the longspine... i can't seem to find any pics on the 'net that look like them.

Any thoughts?

thanks!

 

[fishfarmer]

I'm betting you didn't notice the other urchin, they hide really well, and do grow really fast. I believe urchins broadcast their eggs and spawn into the water where the fertilize, not sure what happens after that.

I have several sized urchins in both my systems, some I took off of a fellow reefer who got too many on his rock. If you grow tired of your urchins try to see if your LFS would take them off your hands or find a local reefer who recently setup a tank and has algae problems.....then there's always sushi .

 

[SPC]

As Fishfarmer said, urchins use broadcast reproduction methods. I am guessing that the type of urchins you have are the common rock boring urchin. I have 2 of these in my 180 and they have spawned on the last three straight full moons. They spawn between 8 and 9 pm finding the highest spot in the tank along with a high current area. The clouding of the tank is quite significant during these episodes but I have seen no adverse reactions to any of the other animals in my system. Keep in mind that any of the spawn that makes it to fertilization would have to go through a planktonic stage which means that they would have to avoid being eaten. I have seen no baby urchins BTW.
Steve