rodbigelow

While many people report them to be a fairly non aggressive species, my marmorkreb attacks and kills anything I put in her tank, including eating her own clutches of eggs.

OK, so last August I got 5 marmorkrebs, very young. I accidently killed one in an unfortunate cleaning accident, and three others died mysteriously, leaving me with one. She was very aggressive and would eat anything that went into her tank. ANYTHING. She ate her first clutch, although I didn't quite put it together at the time. She had a second clutch and they all mysteriously dissapeared, that's when I finally figured out she was eating them. So I dubbed her Highlander, since their could be only one. I moved her to a different tank hoping that one would stress her less and she would allow some babies to live. In the meantime, two weeks after I moved her, I noticed a tiny one that had survived her in the old tank, so I began feeding it. She is much older then Highlander when I first got her and she has kept a very distinctive blue color. They both have the same diet. Is this a color morph or is there some other factor in play? Anyone else ever see this in Marmorkrebs?

hey there, sorry I'm too new to tell you anything about this, but besides this being a smaller subgrouping of the shrimp people so less see postings here, there is another thread just a bit older with the same title that has a bit of information on the subject.

I'll try to get a decent picture. I'm fairly new to Macro photography and don't have anything close to an optimal set-up, but occasionally I get a decent shot.

Grrr....had another fatality today so I'm down to two. It was such a stupid and avoidable fatality too. I hadn't realized it but my largest had just shed and I did a 20% water change. While siphoning I had to look away for a moment and the siphon went astray and grabbed up the freshly molted one and banged it around inside the tubing before I realized what had happened. Going to come up with a better solution for doing water changes immediatly. Was planing on it anyway so when I have a bunch of young they don't get swept up, but this makes a good arguement to change systems now.

That is a possibility. Only way to find out would be to separate out a bunch of young ones at hatching and keep them apart and see what poses they adopt. Once I get better set up I'll try that. It's near the end of week 3 since I got them and growth rate on the largest two seems to have slowed down, with only about 1/2 the former size being put on. Shells are getting more color,and or less transparent which is helping with color. The smallest just today began recognizing feeding time, so it would appear to warrent looking into when I'm set up a bit better, have larger populations to look at and ways to get accurate measurements. What are other people feeding theirs? I'm using veggie pellets, color flakes and guppy bites right now and they are in a planted tank by themselves. So far the only vegetation they seem to be eating is dead and dying leaves.

Maybe, I don't get any red lines at all here. The second largest has now started recognizing feeding time, and it is roughly the same size as the largest when it did the same. The smallest one is quite a bit smaller, and probably won't hit that size until maybe mid to end of this coming week. It will be interesting to see what happens, and this isn't near large enough a group being studied to offically say so, but it does look like a developemental thing. Maybe the brain has to get "just big enough" to start handeling that information. Looking at my photos I also realized they all have exactly the same "at rest" pose. both front claws facing downward at maybe a 30deg angle, with one slightly raised and offset compared to the other. Must have come about as an ideal hunting pose. I was getting confused because the pictures all looked so much the same even when I knew it was different ones in each photo.....

I knew the patterning and coloration could be different, but just didn't think growth rate would be effected that much. Yeah, our little gals should soon offically be declared a new species, and one that's only been around for such a short period of time too! That's one of the things that facinates me so much about them, there are tons of questions that haven't even been asked yet but will eventually need to be answered about our "virgin crayfish" and how this strategy plays out for species survival. BTW-WTH? why doesn't this forum provide spell check as an option before posting? Mildly dyslexic and really hate when I post mis spellings and whatnot.

Now that is interesting, and good to know. I was assuming since they are clones growth rate would be about the same in any given clutch. Makes me wonder what the inluence is there and if there might not be a way to.......I don't even know what you'd call it since you can't breed two together.......to enhance the growth rate in a lineage for possibly bigger crays?

lot of info in this thread, thanks. It's helping me with ideas for set-ups with marbled crayfish

Forgive my wording if it offends, however it is possible for something to be a living thing and also a test subject, and I do respect the geometry(?) of nature. Right at this moment I am not doing anything other then observing anything I can about them, so I can better understand what and who I am dealing with. At this stage it is horribly inaccurate as I bought these at a very young age but they are all so varied in size I have to assume they are from different hatchings and do not have the data as to when each was born. Totally unfamiliar with Stanley Milgram or his experiments.

yeah, I am primarily looking for aquaponic/feeder/any other type of application I can figure out for them. They are pretty cool little test subjects. It's now 2 weeks since I got the 4. I've had one fatality, possibly a bad molt, but don't know for certain. The rest are doing very well and the largest is now 4x the width of my pinkie fingernail (terribly scientific measurement there, I know), so at this age they are still doubling in size every week. It is also interesting that the largest one has now started recognizing feeding time, the 2 remaining smaller ones have not. Will be interesting to learn if this is a developemental thing or not.

From Scienceshot: Crayfish create a new species of female ‘superclones’ By Elizabeth Pennisi 26 August 2015 1:00 pm 9 Comments What happened to the slough crayfish is every macho man's nightmare. A genetic glitch allowed one female to begin cloning herself, and because these females are larger and more prolific, they started to take over. A new study argues that these clones constitute a new species—one where every individual is genetically identical. The all-female clones were first discovered in 1995 by German pet traders and quickly became a popular addition to home aquariums. Later, they escaped into the wild, where they have become a threat to native crayfish in several places, including Madagascar. Genetically, the clones—known as marbled crayfish because of their appearance (see image above)—are similar to slough crayfish (Procambarus fallax), which are found in Florida and Georgia, except they have three sets of chromosomes instead of the typical two. In the new study, published this month on the bioRxiv preprint server, researchers show that the slough crayfish males can’t fertilize marbled crayfish eggs, a hallmark of a species split, and that the clones contain enough genetic differences to justify designating them a separate species. Generally, new species arise gradually over long periods of time, but the genetic studies indicate that in this case speciation was virtually instantaneous, something that happens in plants but is very rare in animals. And the marbled crayfish is the only one among its 14,000 crustacean relatives able to clone itself. Differences in chemical modifications of the two species' DNA seem to account for the superior size and fecundity, the group reports. The researchers are now analyzing these so-called epigenetic differences in more detail and are proposing this new species be called Procambarus virginalis—the virgin form of the genus Procambarus. Posted in Biology, Plants & Animals

well, I can't say how old they were when I got them, but the largest of the 4 was not even the width across my pinkie nail. Now a week later it is more then twice as long as the width of my pinkie nail. Hopefully that is a good sign they are healthy and on track.