Reefs.org Forums

[philosophicles]

I have many pics and videos of various small bugs, some I have seen on this site, and some I have not!

[mariob]

Not exactly a bug but Convolutriloba sp., a flatworm. These are pests in reef aquariums.

mario

[philosophicles]

I thought as much, but didn't want to jump to conclusions. As for it being a pest, I have not witnessed any problems related to it! Could you be more specific?

[LeslieH]

Convolutriloba species have 3 points at the rear end of their bodies. This is in a different genus. The shape is typical of Amphiscolops but since identification is based mostly on internal characters it's impossible to say which genus for sure.

[philosophicles]

Nice, you sure know you stuff! Are you a professor?

[LeslieH]

I'm a marine worm specialist who loves inverts.

[LeslieH]

I'm a marine worm specialist at the Natural History Museum of Los Angeles County who also loves inverts.

[philosophicles]

I had some video footage of some tiny red worms on my glass a couple of years ago, but lost them somehow. I have not seen them since, so I assumed they were a pest that eventually got put in check by my shrimp.

[tomshannon]

Hey Leslie,
Nice catch on the morphology... as I constantly tell my students, much can be learned in the name of a species alone, i.e., Convolu-tri-loba.

Nice to see another vermiformophile out there

[LeslieH]

Back at ya, Tom

Folks - Tom is THE expert on Convolutriloba and even has a picture key on the 4 known species on his web site. And if you want to know how species are defined check out his latest paper http://www.mapress.com/zootaxa/2007f/zt01525p017.pdf It's on the nifty new species Tom uses as his avatar

Now if you could just figure out a way to eliminate them from a reef tank instead of breeding them you'd be a reef god Tom!

[tomshannon]

"Now if you could just figure out a way to eliminate them from a reef tank instead of breeding them you'd be a reef god Tom!"

Yeah, but then I'd be one of those Old Testament "smiting" gods as far as my subjects (the worms) are concerned...

I really and truly see no reason to rid aquaria of the worms; folks just need to learn that like any other animal, these guys will go through a population explosion if resources are high enough (usually caused by over-feeding with Artemia or the like). Just like other animals, too, their populations will wax and wane accordingly and eventually level out at carrying capacity.

Left to their own devices, these guys reproduce almost exclusively (except for C. macropyga) by asexual reproduction, and populations usually crash in a year or two due to accrued somatic mutations, in other words, eventually individuals are asexually produced with so many mutations that they are no longer viable or cannot asexually reproduce themselves... google Muller's Ratchet for a better explanation.

Finally to everyone who was wondering why I responded to a post from last year... my apologies, I found the post in a web search and misread 2007 as 2008. I've been cutting back on my caffeine intake

[LeslieH]

From reading the various posts about flatworms "plagues" the main concerns people have are 1) will they damage my corals? 2) will they eat something beneficial? 3) will they produce toxins when they die - especially if there's a lot of them? 4) they're ugly & icky. Reef wisdom says that even if they're not directly preying on corals these will block sunlight from corals & impede their growth. A year or two is too long to wait for most hobbyists so requests for info on how to get rid of them are a constant on the boards. I don't keep tanks but if I did any & all worms would be welcome!

Doesn't matter how old a post is or how much caffeine you ingest if you're adding new information.

[tomshannon]

Bear in mind that I am only speaking on behalf of Convolutrilobids...

1) Will they damage my corals?

Absolutely not. Contrary to popular belief they do not feed on coral tissue, nor do they obtain their algal symbionts from corals, through consumption or otherwise. The acoel symbionts are "green" prasinophyte algae, most likely Tetraselmis sp. Corals, on the other hand, harbor "brown" dinoflagellate algae of the Genus Symbiodinium. Convolutriloba feed on tiny crustaceans or crustacean larvae, rotifers, and other tiny invertebrates; not diatoms, as is commonly assumed. They are ambush predators.

2) Will they eat something beneficial?

Depends on what you're calling "beneficial". Will they eat the pretty macro-stuff in your tank? No. They will compete with other critters in your tank for resources such as copepods, Artemia, etc., but no more than any other carnivore/omnivore. The main difference that becomes apparent rather quickly is that their population growth responds much faster to changes in resource (food) availability than that of larger "desired" invertebrates and fish. Please note, however, before worrying that they will starve out your corals and wipe out your copepod populations, that their numbers will fall in response to resource scarcity just as quickly as they rose in response to resource abundance.

3) Will they produce toxins when they die?

No, but they will if they are killed. When food is scarce the acoels will begin to starve, and just like most other animals, starvation leads to rapid weight loss. The Convolutriloba cannot survive indefinitely on algal photosynthesis alone. Before these animals die from starvation, they are so small and depleted that upon their death their bodies contain little or no toxin. When the acoels are killed, however, be it by chemical warfare, salinity changes, temperature changes, predation, maceration, or squishing, they will release a potent toxin and make life pretty miserable for the other tank denizens... Food for thought: the death of a medium-sized tang, if unnoticed, will cause a spike in a tanks ammonium levels and make everyone's lives just as miserable; but you never hear anyone preaching to KILL KILL KILL all medium-sized tangs.

4) They're ugly & icky.

So's my aunt. She's even got a moustache, but I'm not about to condone her eradication or banishment from the biosphere. Beauty is in the eye of the beholder.

5) Reef wisdom says they will block sunlight from corals.

Reef wisdom ain't as wise as it thinks it is . For the most part, Convolutriloba don't like hanging out on coral; corals sting. They are more often found along the bottom edges and corners of tanks, on live-rock outcroppings, or just outside of shadows on the substrate. This isn't to say that they never climb onto corals (certain Sarcophyton capitulae seem to attract them at times), but unlike some Waminoa species, it's not their usual modus operandi.

6) A year or two is too long to wait for most hobbyists.

That is how long it usually takes for a population to die off on its own. By no means does this imply that one will have gazillions of Convolutriloba for two years, then suddenly none. Again, the populations wax and wane according to resource availability. The best way to keep the numbers in check is to know your system; know how much food is enough to keep everything in your tank happy and healthy; and don't feed it any more than that. By carefully monitoring the addition of food, everything in your tank benefits and you won't experience large-scale population explosions of Convolutriloba. Eventually they'll just slowly wither away to nothing .

[tomshannon]

In order to give this part of the conversation its proper due under a more apt title, I'm going to copy the above manifesto to my post on Convolutriloba Identification on this board at: http://www.reefs.org/phpBB2/viewtopic.php?t=120853

[LeslieH]

Tom, that's absolutely invaluable information for reefers, thank you. I'm sure everyone who reads it will be extremely happy that you answered a year-old post. Perhaps this would take too much time but including the same information on your website for future reference would be a great service to aquarists. (although your aunt might be a bit miffed if she ever saw it!)

[philosophicles]

It may be a year old, but I still recieve an e-mail notice that a response has been posted and I always check them. So type away no matter how old!

[thecommersoni]

nice pic of the close up

[philosophicles]

Thanks, I also have many videos of them close-up!