Sexing method for living centipedes

[Ridoo]

Hello,

the successful breeding of centipedes is not well studied, hence there are not many publications available so far. In general, sexing centipedes is not an ordinary practice in hobby. Secondary sexual dimorphisms are only visible in some certain species (e.g. bristeled tarsi on terminal legs of Scolopendra dalmatica, ridged prefemur, femur, tibia and tarsus 1 in S. morsitans males). By first external look, males and females assemble each other. In husbandry of centipedes an external sex determination has only been possible by chance and feel until now. By far it has been only possible to spot a female by clutch in captivity - it has been even more difficult to sex a male.

A relatively unusual method is sexing by primary sexual dimorphisms, thus analysis of the genital region. This method was already successfully applied by taxonomists in past (KLINGEL, 1960; RADL, 1993) for S. cingulata.

In males of Scolopendra cingulata a spinning organ, usually named “penis”, is visible. The function of the spinning organ is based on the fact that most of the described centipedes mate indirectly, that means: a spermatophore is placed in a web that is picked up by a female after mating process has finished.

The spinning organ is located next to the 2nd genital sternite, which acts as a protection for the hidden spinning organ.

The 2nd genital sternite is again hidden under the 1st genital sternite. The 1st genital sternite is embedded in a slot of the 21st sternite where also the external digestive region is located.

E.g. males of Scolopendra subspinipes dehaani bear gonopods at the posterior margin of the first genital sternite.

Fig. 1 - Scolopendra subspinipes dehaani ♂:




Unlike in females there is neither a spinning organ visible, nor a 2nd genital segment and, of course, no explicitly visible acute/long gonopods. In female centipedes only the first genital sternite is clearly noticable and the genital atrium is visible as well (ROSENBERG, 2009).

Fig. 2 - Scolopendra subspinipes dehaani ♀:




Living centipedes have a muscularly system to hold back the external digestive and genital region. To disable this function and to make it possible that external and digestive genital region becomes visible,
it is therefore necessary to find a method to slacken the centipede both externally and internally. One promising method is to anaesthetise the centipede with carbon dioxide (KLINGEL, 1960; RADL, 1993).

It is reasonable to focus further elaboration of this method and to find out if it is successful and applicable to most representatives of genera Scolopendra and even other genera in family Scolopendromorpha.

Materials used:

1x canister with carbon dioxide, most practicable with a system that allows monitored dosage (in Germany it is possible to use a "soda stream" that is mainly used for manual production of sparkling water at home).
1x plastic box, about 15x15 cm (depending on the size of the animal)
1x digital camera or a magnifying glass
1x tool for pushing out the genital region (depending on the size of the
animal: a spoon, a pen or a screwdriver)

Preparation:
To make the anaesthetising of centipede with CO2 as simple as possible, a commercial "soda stream" can be used.

Additionally a plastic box which is adapted to the size of
the centipede should be prepared.

A small hole (0, 5-1 cm in diameter) can be drilled directly on the corner of the lid to provoke a secure and controlled infusion of carbon dioxide. The safest and best method to place the centipede in a small box is to use tweezers and possibly a second bigger enclosure to avoid escape attempts.

As CO2 outweighs oxygen it is helpful to drill some additional holes in the enclosure lid to let the oxygen exhaust. The shaft of the "soda stream" can now be sticked into the drilled hole, so that the box with the centipede can be loaded with CO2 which leads to a volatilization of oxygen. The dosage of carbon dioxide depends on the size of the centipede.
Usually it is safe to push four times for approximately three seconds for each push to anaesthetise centipedes from 7 to 19 cm bodylength. Waiting for additional 30 seconds is recommended to ensure the centipede not only looses complete mobility but also strength of musculature.

Method:
The next mentioned steps should be processed without delays. The camera and the necessary tools should be also prepared. After the gas has been injected and the box finally opened the centipede regains in less then a minute body control again.

After ensuring that the centipede is unconscious, it is possible to put slight pressure on the 20th sternite with the help of a tool (e.g. backside of a screwdriver, pen or spoon). The best applicable tool depends on the size of the centipede.

The genital region puts out from the 21st sternite. While keeping the pressure it is necessary to make a high quality lateral macro picture of the genital/digestive region. Alternatively a magnifying glass can be used to observe the genital region. Nevertheless it is possible that the centipede has too powerful control of the inner musculature and thus is still able to hold back the inner genital region. If that's the case either some more carbon dioxide can be injected or a second trial started later on, because the most effective unconsciousness can be provoked by a high dose of carbon dioxide in short time.

After the examination has finished the centipede should be put into its original enclosure again - This step must be completed as fast as possible to avoid being bitten by a slightly recovering centipede.

After a short period of time, the centipede has regained power again. During the time of examination the centipede should be handled with care because its body is very soft, flabby and therefore extremely vulnerable. Due to the lack of body tension, the risk of injury stays very high.

Results:
Turgut and me were able to sex more than 90 percent of our centipedes.

Therefore it was possible to collect data from different species to evaluate their primary sexual dimorphisms. The main benefit is the fact that animals stay alive during and after the examination. RADL also reported that the centipedes haven’t carried off any damage. A short time after the anaesthesia they were very fast and active again. Even with my centipedes, I couldn’t see a change in healthiness or even a disease.

But we also had some deviant results: A different external genital appearance can be seen at S. multidens. Male specimen are missing gonopods.
After DEMANGE, S. valida doesn't have visible gonopods as well.

This may be applicable to a lot of other genera with a high certainty. However, due to lack of conspecifics, this is not proven.
In future, I hope some people will try this method and post some pictures to share this information with others.

Many thanks to Turgut Kocer for helping me with the analysis and the detail photos of his centipedes!

Important notice: You can’t say for sure, that carbon dioxide doesn’t harm the animals at last. I am not liable for damages on health in humans and animals, each acting independently. Also, I assume no liability for damage to the aforementioned technical equipment due to improper use.

Used literature:
Klingel, Hans, Vergleichende Verhaltensbiologie Verhaltensbiologie der Chilopoden Scutigera coleoptrata und Scolopendra cingulata, Mainz, 1960, 16.
Würmli, Marcus - Statistische Untersuchungen zur Systematik und postembryonalen Entwicklung der Scolopendra canidens-Gruppe, 1980, 324.
Rosenberg, Jörg - Die Hundertfüßer (Chilopoda), 2009, 261-263.
Bücherl, Wolfgang - Estudo comparado dos órgãos sexuais externos dos Quilópodos do Brasil, 1942, 19.
Demange, J. M. - Accessory sex glands (Arthropoda-Myriapoda), 1988, 483.
Radl, Ruth - Ueber Lebenszyklus, Fortpflanzung und Brutpflege des Hundertfüssers Scolopendra cingulata (Chilopoda, Scolopendromorpha), 1993,

List of abbreviations used in the attached pictures:

A: Anal orifice
At: Anal tergite
Av: Anal valves
Cx: Coxopleuron
Ga: Genital atrium
Go: Gonopods
Gs1: Genital sternite 1
Gs2: Genital sternite 2
Is: Intersegmental membrane
Rsg: 21st sternite
Sp: Spinning organ

Regards,
René

[peterbourbon]

[ftorres]

Hello All,
Wow Wow Wow!!!!!!! Great info very detail information and superb pictures.

I could see this material being use in the next Centipede book.

good luck.

francisco

[ranchulas]

Holy crap that is an awesome post!!!! Way to go!!!

[What]

I know Turgut mentioned this to me a week or two ago... but seeing the specifics. Wow!

<-- posting in an epic thread.

Thank you both for the work you put into this, the breeding segment of the centipede hobby just gained a large chunk of certainty.

Perhaps this opens the door to research on ratios of genders in broods...and how to influence them, if at all possible.

[Galapoheros]

Whoohoo! You have been busy! Finally somebody got serious about it, took the time and really did it. Nice job!

[rasputin]

I don't think I ever could have committed myself to such work - amazingly done, kudos!

[plo]

Thank You Thank You Thank You !!!! Hopefuly this will lead to many more sucessful breeding attempts of the more costly and coveted pedes out there

[SAn]

gj again on another topic. Breakthrough

[zonbonzovi]

Amazing work, chaps! Not sure if I missed it, but: on average, how long does it take for the centipede to awaken from its CO2 induced slumber?

[Ridoo]

Hello,

thanks

the centipede regains power after approx. 1 minute (Based on the contained oxygen, after the enclosure is opened). Of course, in relation to the duration of time!

For a skilled anesthetist:
To gas one centipede, it takes about 5 to 10 minutes. Including the analysis.

You will need a bit practise, but its easier than it looks!

Regards,
René

[Scourge]

Amazing work work guys! Thanks for taking the time, and for sharing.

[moose35]

thanks guys...this is great.
thanks for your time and effort


moose

[zonbonzovi]

Hey all- just wanted to throw this link out there for anybody(like me) trying to work with CO2 "on the cheap". Posts #45-#54 detail the process(thank you jadespider & Talkenlate):

http://www.arachnoboards.com/ab/show...hlight=surgery

[Bifrost]

Hi, can this method be used also with cast skin? I dont like that part about anaesthetising centipede...