Telling when a stomatopod is preparing to molt

[Gonodactylus]

his Pseudosquillana richeri molted the day after I took this photo. Note the setae (hairs) inside the antennal scales. These form a few days prior to the molt and then evert when the animal sheds its old skin. In species with nearly clear scales such as this one, it is easy to tell when a molt is approaching by looking at the setal development.

Roy

 

[BALISTIK]

Awesome! Knowing when the mantis is about to molt can prove vital in ensuring a proper, stress-free, and successful molt. Appreciate the research and information Dr. Roy.

 

[Gonodactylus]

Thanks. Setagenesis is the best way to determine where animals are in their molt cycle and it allows you predict a molt several days in advance. However, it is difficult to do with small animals without a dissecting scope. Also, often the antennal scales are pigmented masking the development. We actually use the pleopods (gills) which are transparent and readily show setal development.

There are other cues that are also reliable, but which do not develop that much before a molt. For a day or so before a molt, you can see the sixth, seventh and eighth thoracic tergites beginning to weaking on the mid-line. This is where the tergites will split and the animal squeeze out of its old exoskeleton. When first visible, fracture points are just faint lines on the mid-line.

Many stomatopods, particularly gonodactyloids, also sequester calcium in glands that are found in each thoracic and addominal segment. They become white- almost chalkish a few days before a molt. You can see them at the lateral edges of the ventral sternites. See the attached photo.


Roy

 

[rlf_racing]

Dr. Roy can you also predict the molt of a O.S. mantis. I have a 3.5" male that is showing possible small signs of shell disease. Do you need to add a calcium supplement to the tank to help? Here is a picture of my little guy.

 

[helipilot]

Thanks Dr. Roy. Great information! I think we all dread the deadly molt. Maybe now we can anticipate it, and prepare the mantis for a successful molt.

 

[Gonodactylus]

Antennal scale setagenesis won't work with O. scyllarus, but the tergite sutures do desolve and the large patch of slightly "off" color does form on the dorsal abdominal tergites. Setagenesis in the pleopods also works, but it is hard and dangerous to clip a sample to put under a scope.

Roy

 

[KafudaFish]

Are there any behavioral changes as well Dr. Roy?
My peacock will become very active like it is searching for additional food for a few days then the activity level decreases as well as not eating any given food. This is usually over the span of about a week. It will then disappear completely which I believe is when the molt occurs and then it returns to its normal routinues about 5 days after the first day of MIA.
Thanks.

 

[Gonodactylus]

The behavioral changes are pretty much as you describe, although the searching that you mention is actually construction or searching for a new burrow. They often do a lot of digging and moving things around. They will also become more aggressive. The ability to strike wanes a day or two prior to the molt. The bigger the animal, the longer the cycle so a 2 inch O. s will not eat for only a day before and after the molt. A 6 inch animals may go for 3 or 4 days before and after the molt without eating with the exception of the soft parts of the shed exoskeleton.

Roy