Whoa - Things got kinda hostile all the sudden... Let's get back to exchanging information
Jawbone - I know how hard it is to watch an animal languish and perish in the LFS when you're convinced it would fare better in your aquarium at home. I
know that the shop has to lose money before they'll stop bringing in certain animals, but that doesn't make it any easier for me to walk away and let the animal die there either, and I must admit that I've done the same thing, myself - I for one certainly can't fault you for that! I think that the backlash is simply because your first response to Dustint came across as "don't worry, they're easy." I suspect that you did not intend that to be the message in your posst (because you later explain that you researched the requirements of the worms and decided against getting them in the past), but that that is how your initial post comes across, at least to me. Now having said that, I am not convinced that the worms in your picture are
Spirobranchus. It's pretty hard for me to tell from the picture, but I see at least 2 different kinds of worms there. You notice how the feeding pinnules are arranged in a spiral whorl in the picture posted by Steve above? That spiral whorl is one of the easily identified characteristics of
Spirobranchus, and I just can't tell for sure whether or not any of your worms have that specific pattern to the feeding crown. It looks to me more like some of them may have it, but others (like the small one you indicate on the upper left) look like they are almost certainly a single-layered double crown of feeding pinnules to me. I'm guessing that these worms that you see growing on your rock are one of the multitude of brightly colored species of
Hydroides or
Serpula (both of which can grow to reproductive maturity extremely quickly, and some of which are capable of reproduction in the aquarium) rather than the true "Christmas tree worms" of the genus
Spirobranchus. I suspected that there was some minor misidentification or LFS common-naming problem at fault when your experience was contrary to what is known about the biology of this species.
It's not unbelievable at all that the worms are alive in the absence of the
Porites. I'll have to get into the details of the association between
Porites and
Spirobranchus in detail for Advanced Aquarist somewhere down the line, but the short of it is that the worms are found to naturally associate with several species of corals, and
Porites happens to be the coral associate in which the growth rate of these worms is actually the
lowest. There is no evidence to suggest that the association is obligate for the worms, or that they gain any nutrition at all from the coral. Instead the association seems to derive from larval settlement preferences, and there appears to be considerable variation within and among worms in the preference of their larvae for different corals. It's really pretty complicated, but assuming that the worms gain sufficient food from suspension feeding in the aquarium, so far as marine biologists know right now, there does not appear to be any reason that they should require the coral to survive...
Steve - you're quite right that the worms could well have been small at the time that the rock was added. The larvae metamorphose at roughly 3-400 microns and they are essentially clear at that point (I have some pictures if you're interested?), so it's not like anyone would ever notice them if they were newly settled on the rock. Assuming that they can grow at the maximum rate observed to date, it would take about 1 year for them to reach 1 mm in diameter, and I could easily see a worm that size being overlooked on a
Porites colony...
Of course, it is also possible that the worms really did reproduce and that my estimation of the survival probability of a long-term feeding larva in the average reef aquarium is wrong. I should have said that I know of no documented reports of reproduction for
Spirobranchus in an aquarium to date. I have heard such reports, but every one that I have heard of was similar to yours when I spoke to the people - the worms always show up on the same rock, even when there are other colonies of the same species of coral in the tank. Even with a >80% larval preference for settling on a live coral, if the worms really spawned, we should expect some small proportion of the larvae to show up *somewhere* else in the tank. No one I have ever spoken to has seen them spread in the aquarium, but if yours do, please let me know! My feeling is that given the vast number of other invertebrate species that produce
much larger and hardier larvae with
much shorter larval periods, and that these animals still fail to settle when they are seen regularly spawning in the aquarium, I would put my money on the larvae not surviving the planktonic period...
Rob
[ February 26, 2002: Message edited by: Biogeek ]</p>
