So how long will it take for my stomatopod to molt and what is it doing?
 

One question that I'm frequently asked is how long does it take for my stomatopod to molt. As is typically the case with stomatopods, the answer depends on the species and the size of the individual. I thought it might be useful to briefly describe the process - without a lot of the endocrinology and physiology. Hopefully this will help you understand what your stomatopod is doing.

The molt cycle is made up of a series of steps. During the intermolt not much happens initially, but then the animal starts to lay down a new cuticle under the old one. As it approaches the molt, minerals are pulled from the old cuticle and stored in special glands. You sometimes can see these as chalky looking structures inside the ventral edge of each segment. The animal will then start to prepare for the molt and its behavior will change. It may become increasingly aggressive, undertake major reconstruction of its home, and finally stop eating. At this point, things really start to happen. The old cuticle starts to lift up creating a fluid filled space between the new and old cuticle, the animal may (depending on the species) seal itself in its cavity or burrow, and the sixth, seventh and eight thoracic tergites (dorsal plates) start to weaken on the dorsal midline.

As the actual molt (ecdysis) begins, the animal increases its fluid volume and starts to contract opposing sets of muscles increasing the internal hydrostatic pressure causing the thoracic tergites to rupture. The animal jack-knifes and begins to force itself through the dorsal thoracic opening. Interal pressure is rupturing other suture lines of the cuticle so that eyes, limbs and gills can be pulled free. If everything works according to plan, the animal will pull completely free of the molt skin in a mater of minutes leaving behind a perfectly articulate molt skin with all pieces connected except for the carapace which falls free. As the animal frees itself, it maintains high internal pressure and everts its new setae. These had developed inside the body like the fingers of a glove that had been pushed inside out into the center of the glove. The process is like taking a rubber glove, weakly inflating it and pushing the fingers into the interior of the glove. Then when you blow into it to increase the pressure, the fingers (setae) pop out.

The actual ecdysis is the time of greatest danger for the stomatopod. If any of the old cutlicle is stuck to the new due to wounds or disease, it will be unable to pull free. This is often fatal particularly if the gills remain covered suffocating the stomatopod. Commonly, the raptorial appendages become stuck. This occurs because of their great size and the small oriface that they have to be squeezed through. When this happens, the animal may be able to tear off the offending appendage to free itself - but at a cost since it will take three or four additional molts to regenerate a new one.

As the molt skin is shed, the animal begins the tanning process hardening the cuticle and redepositing salts. Any appendage that is stuck or deformed at this point will now remain in this condition. The cuticle will quickly strengthen sufficiently to allow normal movement (but not a strike). Usually the softer parts of the old cuticle are eaten providing nutrients and additional minerals although it may take a couple of days before the jaws are sufficiently hardened to allow the stomatopod to eat the harder parts. Some species such as odontodactylids may bury the old cuticle away from the burrow and then dig it up later to eat it. As the cuticle continues to harden, the animal will eventually open its cavity or burrow and when it can strike, beginning to forage. Many species will initially take soft prey, but smashing specialists will often remain sealed until they are able to strike with sufficient force to break snails and crabs.

So how long does all this take? There is no simple answer because it depends on the species as well as the size of the animal. You can view the molting process in stomatopods as an ever increasing spiral. Each 360 degree turn is one molting cycle and the circumference is the time it takes to complete that cycle. For example, a juvenile Neoonodactlylus wennerae 8 mm long will molt very couple of weeks and the actual molt from closing to opening may be only a day. Six months later at 18 mm, the animal molts about once a month and remains sealed for two or three days. At one year, a 25 mm animal will molt every one to two months and close or 3 or 4 days. At 3 years, a 40 mm N. wennerae will molt every 3 or 4 month and may remain closed for over a week, etc.

In general, heavily armored species for a given size take longer to complete a molt cycle. However, it is hard to generalize. Some species like G. chiragra and G. platysoma spend a very long time sealed in their cavities. It is not unusual for an 8 cm G. platysomal to remain closed for three weeks. An Odontodactylus scyllarus the same size would close for less than a week.

***** Added data
The molting process starts weeks or even months (in large animals) before the actual ecdysis (shedding of the old molt skin). The must lay down an entire new molt skin underneath the old one. (You can sometimes see the setae of the antennal scales growing into the antennal scales. They grow inside out and at the time of the molt pressure causes them to "pop out" much like the fingers of a rubber glove that is inside out and you blow into it.) As the molt nears, minerals are withdrawn from the old cuticle and stored in glands in the body. You can sometimes see these as while glands in each segment of the thorax and abdomen along the ventral lateral surface. Closer still to the molt, the old cuticle begins to raise up and a fluid filled space opens between the old and new cuticle. A few hours before the molt, suture lines begin to weaken. You can see these as lines on the dorsal mid-line of the thoracic segments. They run completely across the tergite plates. When it is time to molt, the animal increases fluid in the body (osmotic change) and violently contracts its body muscles to greatly increase internal pressure. This causes the thoracic tergites to split and the animals body is forced into the newly created opening. The animal is now in a jack-knife position working its way out of the old molt skin back first. It is sort of like a breach birth and any loss of hydrostatic pressure or muscular contraction will stop the process and the animal will become stuck and die. Note that during this time the gills are not functioning well until they pull free and are exposed to water. Once free, the animal is so soft that the muscles have nothing to work against except each other and initial movement is by hydostatic pressure changes. However, within minutes the new cuticle begins to "tan" and harden and over the next few days minerals will be added to harden the cuticle to its old functional stiffness. Until that happens, the animal cannot strike and if it tries, it will literally tear the appendage apart.

I won't go into all the things that can and do go wrong, but I think you can see that this is the weak link in the stomatopod's life cycle and a typical gonodactylid will have to do this 25-35 times. Most stomatopods that are not eaten or badly wounded die during the molt simply because of the energetic demands that potential for physical malfunctions.

When we keep stomatopods in an aquarium, we often see them die during a molt and assume that something is terribly wrong. It may not be. Like all organisms, stomatopods die and typically death comes during a molt.

***** End added data

I hope this provides a little help in understanding the molti and the variables that are involved in setting the length of the cycle and the relative duration of the various components of the molting process.

Roy

Excellent information... thanks!

Very good, this post should be pinned on the first side.

I think one thing is very important.

Never disturb the mantis during the molt.

Last week my very shy G. ternatensis male trys to molt and died one day later. I only take a short look at him, because the cavity was not closed. It was enough to disturb him and now he is dead.

good info dr roy thanks


i just got another mantis yesterday and it has one raptorial appendage thats bent to the side so he looks kinda pigeon toed will it become straight again when it molts next or is it gona be pigeon toed for good now? or would it be good to do surgery on it like clipping the bent limb off so it can regernate a new one?
thanks

It may straighten out, but not likely. I have one the same way right now and think I will rmove the dactly.

Roy

Good information! Thanks for the post!

so the larger the species the longer it takes to moult, do they require any special needs during this moult? like a pitch black den or extra nutrients?

I would like to know how long it takes for a 15cm peacock to moult approx :)

thanx for the info on the moulting process

Nothing special except don't bug them by trying to see what is going on in the cavity. Also, try to keep tank parameters constant. This is not a time to allow the temperature to change, to adjust the salinity or probably even clean the sand. By the time the molt is a day or two away, the animal has stopped eating and I would not recommend adding nutrients or supplements. (On more time - where did this myth come from that stomatopods need extra iodine?)

As for how long does it take for a 15 cm O.s to molt - about a minute. If you were asking how long is it between molts, it depends on how much it is eating and for females, if she lays eggs. The average would be every 3 or 4 months, but I've seen well fed large O.s molt in every two months and I've seen some O.s not molt for 6 months. Also, if the animal has lost its raptorial appendages, it will decrease the molt interval.

Roy

As for how long it

Dr. Roy, thanks for posting this information.

When is it ever "OK" to remove a molt? Will it contribute to a decrease in water quality if the molt remains in the tank for an extended period of time (i.e. buried by the mantis somehwere). You mentioned that they eat the soft parts of the molt for extra nutrients, if the molt is removed to avoid degradation of water quality will the mantis be less likely to survive the molt?

If they aren't eaten in a couple of days, I usually remove them. If you are feeding the animal a diet that provides the required nutrients, it should be fine.

Roy

Thanks Dr Roy , stickied this one.

Hey there Dr Roy,

My G smithii has been locked up for over a month. i am hesitant to dig him out just yet. Is this typical for the species/ He is probably about 75 mm long at this point.

Thanks in advance

-Uriel

A month is too long. It does not sound good.

Roy

I've had my 4" Peacock Mantis about 3 months and he hasn't molted (that I know of). I can see him better now in a 55 than before, but I have never seen any indication that he molted. He will occasionally stay in his den and block the entrance, but never more than a couple of days.

He has hermits and snails in his tank that he hunts and I will give him krill once or twice a week. He won't eat silversides at all, and krill isn't his favorite. He prefers the hermits to the snails in his tank.

He eats very well, very active, seems fine, but no molt. Should I be concerned?

I'd say theres a possibility of a parasitic snail. If they get them they won't be able to molt. Look under the mantis. I think thats where they hang out. It should be like a bump or something. If you search the forum there is a pic or 2 somewhere.

Dan

I've had my 5" peacock for a few months now and he has not molted yet... I'm interested to see it

Can i increase the iodine levels in the tank to initiate a molt? I've got a 5" O. Scyllaris with advanced shell disease, to the point that green filamenous algae is growing out of it. I've added a dose of iodine to systems with Lysematid shrimps to rid it of the tiny black parasites in ut's gills, and cave shrimp to grow limbs back in short order. I also used this method on a small gonidactyllids, but i'm not sure how effective the iodine was, as the molt occored 2 days after the trreatment. I'm sure it will take several molts to get rid of scarsfrom the deep erosion.
-Tim

Can i increase the iodine levels in the tank to initiate a molt? I've got a 5" O. Scyllaris with advanced shell disease, to the point that green filamenous algae is growing out of it. I've added a dose of iodine to systems with Lysematid shrimps to rid it of the tiny black parasites in ut's gills, and cave shrimp to grow limbs back in short order. I also used this method on a small gonidactyllids, but i'm not sure how effective the iodine was, as the molt occored 2 days after the trreatment. I'm sure it will take several molts to get rid of scarsfrom the deep erosion.
-Tim

Well this would be my first post, but anyway I have a question possibly concerning molting. I have a red peacock mantis, assumed to be female, just got her about a week ago. I noticed, after I moved the live rock around a bit, that she has a white coloration on parts of her body that was not there when I bought her. The white portions are mainly on her raptorial appendages. Is she molting or has she contracted the dreaded shell disease that I keep hearing about? My water parameters are perfect. Temperature at 80 farenheit constantly. Brand new tank with trickle filter. It makes sense that it would be a molt. She also seems to be cleaning herself a lot, this has me worried. Please will someone give me an answer. I hate to see any organism die, unless it's a mosquito. ;)

Shell disease does not appear in a week and it is not while. I'm not sure what is going on without a picture, but if I had to guess, I would say that she molted and was unable to remove the old moltskin on the raptorial appendages. That would give the rapts a lighter appearance.

Roy

Thanks Roy.
I apprieciate being able to get an answer from a professional.
Should I be concerned if the white portions do not clear up?
Also I noticed that air bubbles appeared to be comming from her, not a lot but a bubble or two when she swam and moved around earlier.

I don't know what would cause the bubbles unless she swam to the surface and trapped bubbles inside the old cuticle. If the old cuticle was not completely shed, she is in trouble and there is little you can do. Sometimes they can remove the cuticle; sometimes they lose their raptorial appendages and have to regenerate them.

However, I want to stress that we don't know what the problem is. I am only guessing without seeing her.

Roy

Before I take a picture of her, is there anything I should know before I start snapping shots? For example, can the flash from the camera damage her vision or scare her? How far should I be from the burrow entrance, or does it even matter? Once I get information on this I'll be able to upload some pics.

Ok, I got a few pics. Sorry about the quality but she does'nt run out that much now, just stays in her cave so the angles are constant.

http://i491.photobucket.com/albums/r...tisraps002.jpg

http://i491.photobucket.com/albums/r...tisraps003.jpg

http://i491.photobucket.com/albums/r...sraps001-1.jpg

IMG]http://i491.photobucket.com/albums/rr277/Koshmar_photos/mantisraps001.jpg[/IMG]

mmm... well it's not a peacock, but beyond that i have no idea. no way to get a better pic?

I guess I'll create a brand new thread soon to Id this little guy or gal, (I can't even be sure of the sex anymore). I guess my lfs mislabbled it "red peacock mantis shrimp." The important part is that I got a pic of the white/clear portion of the raptorial appendages. That is what I have a question over, is it indicative of a molt or something else?

On a seperate note, is molting linked in any way to the lunar phases? After a M.S. molts, if it strikes a hard bodied creature, does it interfere with the harding process of the new exoskeleton?

Well, we know it is a gonodactylid.

Most stomatopods molt in relation to a lunar cycle. Some molt on the full moon, others on the new moon. It depends on the local tidal cycle as well as the depth at which the animal lives. How this is controlled is a bit of a mystery, but animals in my lab often seem to molt synchronously and I suspect that it is related to lunar illumination (the lab has lots of windows). We know that the synchrony last for a few months even when the animals are held in rooms without windows, but we see synchrony in animals that have been in the lab for years. That would seem to be too long to remain synchrony without an external cue.

Stomatopods usually do not strike when molting since the appendage cannot function until the cuticle hardens. If you induce striking prematurely, the appendage can literally tear itself apart.

Roy

Does artificial light have any impact on the molting cycle? If the duration of the lighting is changed often will the molting process be affected?

On a seperate note, I have been told that if a M.S. strikes with its raptorial appendage while out of water the said appendage will rip clean off and fly off of the animal. Is there any truth to this? I know that the density of water and air are vastly different but I find it hard to believe that the M.S. could "shoot" its arm clean off if it struck in the air at something.

So all things considered how long should I expect my little buudy to live.

I may have missed the info, sorry if I'm asking an already answered
question. What is the average life expectancy of a peacock (Odontodactlis
ylus scyllarus) Mine lives in a 120gal tank with about a 6" sanbed and the rockwork was placed to provide him an optimum enviornment for climbing as well as over head protection. He is fed selcon soaked shrimp as well as hermit crabs and many different types of snails so he can eat a natural diet and also keep his bashing appendages strong in working order

The quick answer is no one knows. THere have been no demographic studies done on this species. From experience in the lab, I don't think they are that long-lived. My guess would be 6-8 years, but I would like to hear from anyone who has kept one longer.

Roy

Wow, that was the fastest response in RC history possibly. First off thank you Dr.Roy for your dedication to stomatopods and helping those of us who are fascinated by these wonderful creatures. I am an audio engineer, I provide sound reinforcement for the Louisville Orchestra as well as many well known musicians. I am very passionate about audio and I can honestly say that I love my job, as I can tell how passionate you are about your work, I guess what I'm saying is for all of us who you educate and mentor for no financial benefit or rewards except helping hobbyists and for that you should receive the Reef Central Nobel Prize if there was such a thing. My O.S. Is either in the process of molting or he has passed on to wherever it is that Stomatopods go (other than the bellies of nassarius snails, and serpent starfish)when they die. He was at least 6" long when I got him approx 2 years ago so if he doesn't appear from his burrow soon I guess ill have to make funeral arrangements for his departure. Thanks again for your very rapid response. Your friend and admirer, Reefologist

+1 Reefologist. Excellent post. My O.S. is close to 4" long, and I believe just completed a molt. I have no evidence of this however, except that I saw him twirling a rapt in his mouth last night, which scared me (see my post) only to find that after this was done he came out of his burrow and both rapts were intact. I was at work for 13 hours yesterday, so much could have happened. Could he have eaten his molt in that time period after molting? It was somewhat dark, only blue moonlights, but I couldnt find the rapt molt after he came out, so he could have left it in his burrow. He appears healthy and hopefully he will be a little more active now.

great post! Thanks for the info. I have a 10" or so peacock mantis He has molted about 4 times since I had him (a little under a year!) He is very active, eats well etc.

However the last 2 molts were very hard on him. The first one took over a week for him to completely molt. I would see him swim out one day wiht a piece of old shell, then a couple days later his swimmettes, then a couple days later another piece. His tank is in my office so I saw more of him.

I turn off his lights when he molts to reduce his stress. I even turn off the other tank lights during the time.

On his last molt I thought for sure he was going to die! I come in and he is on his back in the middle of the tank kicking and kicking his swimmettes. He usually closes himself in his den for days when he molts. I turn off his lights and leave him be. He remained on his back out in the open for the remainder of the night. The next day he went back to his den and molted for many many days...2 weeks in fact. He would throw pieces of his shell out of the den during that time.

I guess my question is.....will his molts continue to get harder on him? I have no idea how old he is but like I said he is a good 10". I fret over his molts and i fear he will die in the next one.

He eats very well. He loves krill, silversides, squid not so much, whole raw shrimp, etc. I give him a couple large turbo snails to graze on at least a couple times a month. I soak all his food in Selcon or GVH. Any ideas?

First, let me say that the largest O. scyllarus ever recorded was 175 mm, right at 7 inches. Anything larger than 6 inches is very large for this species and most have trouble molting.

The fact that pieces were thrown out in stages does not mean that he was molting over a long period. Animals often bury their molt skin and then gradually dig it up - sometimes eating the softer parts.

As I've said before, most stomatopods in captivity die during a molt and the older the animal, the more likely it will happen. Such is life (and death) for a stomatopod.

Roy

thanks for the response! the actual size was an estimate...sounds like I was way OVER :mixed: He is larger then all that I have seen before but I am sure he is not THE largest.

I unfortunatly am prepared that he will eventually die...but hoping he will not! Glad to hear that he probably buried his molt! Makes sense:eek1:

10 inches!!!

You probably have the record than

Heres a video i took of mine during her last molt.

Enjoy
http://s488.photobucket.com/albums/r...=Moviedfsg.flv

WoW! Amazing video you got there. Thanks!

Great collection.........

Thanks.......
Good info........

thanks.........
good info...................

I know you've stated a mantis will bury and eat the molt but, would a mantis, like some crabs and shrimp I've had, use the molt as a decoy outside the lair until the shell hardens?

Second that and thanks for all the great info.

A stomatopod molt doesn't look much like a live one. I don't think it would be effective and there is no evidence that they deliberately place the molt skin outside the entrance.

Roy

Good info, my mantis finally molted after a month and a half of having him. He seems to be ok so far but it just happened a few hours ago while i was at work. He is about 4 inches long.

excellent info..

i just lost a gonodactylus smithii during his first malt in the system..truly awesome creatures, was a privelage to share time in such close proximity. just hope i wasn't too much of a stress factor on his last days

When Mantis shrimp molt, are they more "delicate" than say... a cleaner shrimp? It seems as though when Mantis shrimp molt, it's a much bigger "deal" than when a hermit crab or peppermint shrimp molt....?

Yes, stomatopods take longer to recover and are incapacitated more probably because the stomatopods have more armor that takes longer to replace.

Roy

This kinda sux for me. I am in need of doing a water change and my mantis is really close to molting. Anytime ive walked by the tank i took a short glance and he's been on his back all day not moving so clearly he is close. Can cutting the lights for a day speed up his molt? Or make it easier on him?:uhoh2:

This doesn't sound good to me. Stomatopods do not usually lie around on their backs for days prior to molting. With a healthy molt, you typically see increases in digging and aggression a few days prior to molting and the last day or two they can't strike, but not the behavior you describe. If it were me, I would tend to the tank with a partial water change being careful not to stir things up and matching the salinities between the old and new water.

Roy