Another quick thing Kreblak, depending on just how many things you have in your tank, molts usually are quickly consumed. A molt in my tank may last two days. If you have enough inverts, it'll be gone before you notice it.
Shrimp molt
- Thread starter kreblak
- Start date
I have looked at five seperate books on marine animal anatomy and physiology, and have been able to produce a single reference on iodine importance in the molting process. I quote,
"There seems to be a high mortality rate among shrimp that have recently molted, as they molt the entirety of their gills along with the exoskeleton... A stress free environment facilitates higher survival rates for the shrimp. An abundance of hiding places are necessary for the shrimp as it waits for its new exoskeleton to harden. Nutrition is also of the utmost importance, of which Iodine is thought to play a vital role."
That is as specific as I was able to get. The best minds out there "think" iodine plays a vital role, but no one wants to come right out and say how.
I am thinking that it plays an important role in osmoregulation, like it does in human thyroids. Just my hypothesis. Is that worth $10?
"There seems to be a high mortality rate among shrimp that have recently molted, as they molt the entirety of their gills along with the exoskeleton... A stress free environment facilitates higher survival rates for the shrimp. An abundance of hiding places are necessary for the shrimp as it waits for its new exoskeleton to harden. Nutrition is also of the utmost importance, of which Iodine is thought to play a vital role."
That is as specific as I was able to get. The best minds out there "think" iodine plays a vital role, but no one wants to come right out and say how.
I am thinking that it plays an important role in osmoregulation, like it does in human thyroids. Just my hypothesis. Is that worth $10?
Well, it was worth a good chuckle. If that was all it took, then I'd owe VoodooChild $10 too. Just once, I'd love to see one of those "great minds" present a teensy bit of experimental evidence. BTW, if you are interested, the most complete, if somewhat dated reference I have read is Dorothy Skinner's chapter in vol 9 of "The Biology of Crustacea." There are newer reviews, but they don't add much, as far as I can tell.
Not a great mind by any stretch, but some hypothetical proof for the importance of iodine (and where it entered the realm of thought)--brackish crabs being maintained in FW environments seldom molt successfully. While there are an abundance of other differences between the FW and B/SW chemistry, iodine could be one of the key differences that results in molting failure in those crustaceans kept in FW.
There is a lot of information indicating that crustaceans contain a higher level of iodine than other critters--this is one of the reasons many people are allergic to iodine.
There is a lot of information indicating that crustaceans contain a higher level of iodine than other critters--this is one of the reasons many people are allergic to iodine.
That's true. But there's a lot of debate as to whether the iodine needs to be there, or is precipitated as a byproduct of the tanning process in the cuticle.
I have consulted yet another stack of books on crustaceans, and I still cannot find one single line that reads anything like "Iodine is crucial to the molting process because..."
Everything just alludes to iodine being important nutritionally and as an element in the water. This lack of an answer really bugs me...
Everything just alludes to iodine being important nutritionally and as an element in the water. This lack of an answer really bugs me...
Tell me about it. I have been ranting on Reef Central for months, even posted a thread offering the same $10, and have received no info.
I guess it doesn't hurt anybody. But it would feel great to finally know how the whole thing started.
Boogiechillin
It's ok, I confuse my students too.
Mogurnda,
In between drifting off for naps in college zoology, I think that I remember a reference that iodine can be used to stimulate premature crustacean molts in laboratory settings. My guess is that this would actually be detrimental since it probably rushes proecdysis and results in the critter salvaging less of the mineral content from the old exoskeleton. I don't have the reference for this, but it's not much of a leap to go from the use of iodine to forcefully stimulate a molt to a popular belief that iodine is *necessary* for a molt.
Anecdotally, when my tanks were soft coral dominated, I dosed iodine more frequently to stimulate their growth. Granted, this is retrospective, but I seem to recall the shrimp molting more frequently and leaving less-transparent exoskeletons behind, several of which scared me as they were colored enough to look like a dead shrimp. More recent molts that I saw after shifting away from softies and iodine are more translucent.
Definitely not my field, but this is an interesting topic!
In between drifting off for naps in college zoology, I think that I remember a reference that iodine can be used to stimulate premature crustacean molts in laboratory settings. My guess is that this would actually be detrimental since it probably rushes proecdysis and results in the critter salvaging less of the mineral content from the old exoskeleton. I don't have the reference for this, but it's not much of a leap to go from the use of iodine to forcefully stimulate a molt to a popular belief that iodine is *necessary* for a molt.
Anecdotally, when my tanks were soft coral dominated, I dosed iodine more frequently to stimulate their growth. Granted, this is retrospective, but I seem to recall the shrimp molting more frequently and leaving less-transparent exoskeletons behind, several of which scared me as they were colored enough to look like a dead shrimp. More recent molts that I saw after shifting away from softies and iodine are more translucent.
Definitely not my field, but this is an interesting topic!
If dosing iodine into a tank (or labratory setting) can induce a crustacean to molt, then isn't it logical to conclude that iodine is a sort of "trigger" for the crustacean? If the iodine levels in seawater are constant (I think they are) then the crustacean will take in iodine on a regular basis. When enough has accumulated in it's system, it is time for a molt. (in theory) I don't think its much of a stretch to conclude that evolution has built into crustaceans a timing mechanism for their molts based on a constant.
Of course, this assumes that the iodine content of seawater is constant. If it isn't then my theory is shot to *&%$.
Also, it assumes that the molt isn't triggered by growth or some other variable. All in all it isn't a very good hypothesis, but its the best I can come up with right now....I want that $10!
Of course, this assumes that the iodine content of seawater is constant. If it isn't then my theory is shot to *&%$.
Also, it assumes that the molt isn't triggered by growth or some other variable. All in all it isn't a very good hypothesis, but its the best I can come up with right now....I want that $10!Not really. We can get lots of things to happen in the lab using artificial methods, but they don't necessarily indicate the way things work normally.
Under normal circumstances, the molt is controlled by a hormone called ecdysone, or for the type A people out there, a derivative called 20-hydroxyecdysone. The secretion of this hormone is in turn controlled by peptides such as molt inhibiting hormone. Outside factors such as stress boost the secretion of MIH, keeping the animal from molting until the right time.
If, for example, iodine were to inhibit the secretion or function of MIH, it could induce a premature molt.
What I would really, really, really like to see is the reference BogieChillin mentioned about iodine inducing molting. People quote it, but I would love to read it.
