Petshrimp.com Discussion Forum

Hi, I don't know the English name of this cray and since I don't have a picture, I'll try to describe it the best I can.

It is small, not exceeding 3 inches
It is green when young, and when it grows up, it turns blue. It has a attractive pattern of marbled spots on its body
It is an all-female species, so they lay eggs when mature without the need of a male. It also lays them frequently.

Its name was marbled cray, marcrocrebs or something like that.
I saw it once on the internet, and I'm sure somebody is keeping them.
By the way, if you find out the name, does anybody know some good care sheets on it?

Thanks

As far as I know, the Marmorkrebs has yet to be identified as a species and is only known in the aquarium industry.

It is unique because it can produce offspring without mating (parthenogenesis). This makes it a very dangerous species to any natural habitat where it might accidentally be released because a single individual can reproduce and invade the habitat, displacing native species.

Here is a downloadable scientific article on this "species"

http://iz.carnegiemnh.org/crayfish/cfre ... rph261.pdf

I have never seen one of these, so can't offer any advice on keeping them, but even just the correct common name is enough to send you back on a search for information.

A Crayfish Species, That does not need a Mate.
And Changes from Green to Blue as it Matures.

Sounds like a very interesting Species.

As YuccaPatrol Stated.
There will be alot of responsibility, If any Hobbiest decides to keep this Species.

YuccaPatrol
Does a parthenogensis Species, have both sex organs ?

Do you know of any other Invert. Species that reproduces by parthenogenesis ?

It sure is nice to have a Forum Member, with access to this type of Information.

John

No this species doesn't have both sex organs. They are all female.

CanadianCray

I am no Scientist,
And I did pass Sex Ed. in School.

Can you explain, how a Female ( Ovaries )
Can Produce Young ?

Thank You
For any information

John

The marble crayfish clone themselves. Each offspring is identical to the mother. All of the spots on them are in the exact same place.

G. Whitney Stocker (Appalachian Man or Appy for short) did have a male at one time. Males are very rare, but do occaissionally occur.

The reason the marble crayfish turn blue is because of the food, environment and lighting of the tank. It is not genetic.

Here is a little quote from the pdf file that Yucca posted. You should really read it.
http://iz.carnegiemnh.org/crayfish/cfre ... rph261.pdf

Our results revealed
that the external sexual characters and also the
gonads of the marbled crayfish are purely female, making
this fast-reproducing species a good model for investigating
female reproductive features in crayfish. Testicular
tissues, ovotestes, or male gonoducts, gonopores, or gonopods
were never found, either in small juveniles or large
adult specimens, confirming the parthenogenetic nature
of this crayfish.

Some other links regarding this species.
http://users.swing.be/sw018249/procambarus_sp_uk.htm

http://www.newscientist.com/article/mg1 ... aters.html

http://images.google.ca/images?hl=en&ie ... a=N&tab=wi

You can do searches for :

Marble crayfish
Marmor Krebse
Procambarus sp. Marble

Here is another good article about them.

http://iz.carnegiemnh.org/crayfish/cfre ... EZ303A.pdf

One article I saw indicated these are native to the US. If so, anyone know where they would be found?

As far as I know, this "species" only exists in captivity. My best *guess* is that this is a hybrid of two related species. One interesting thing about many invertebrates is that they may not conform to strict rules when it comes to chromosome numbers. Again, I am *guessing*, but perhaps this hybrid has a re-arranged number of chromosomes which make it possible for unfertilized eggs to contain all the chromosomes necessary for complete development.

Regardless of the exact mechanism for their reproduction, it does seem that this is not a naturally occurring species but a freak result of someone along the line keeping two species of crayfish together and coming up with this odd creature.

There are certainly naturally occurring species out there that do reproduce through parthenogenesis, but no other decapod (crab, crayfish, lobster, shrimp) is known to to this.

Edit: NewJohn, generally parthenogenesis is defined as females asexually reducing to produce more females.

badflash wrote:One article I saw indicated these are native to the US. If so, anyone know where they would be found?

Since there have been no known males occuring in this species when studied. There is no way to know what species they are as you need a male crayfish in breeding form 1. There has been some DNA testing done on these crayfish & it is a common belief that they could be a variation of Procambarus (Ortmannicus) fallax.

Thanks guys. Does anybody know from experiance what the minimum tank size is for 4~10 of these crayfish?

I don't know what size tank is needed for that many, but I put 3 in a 40 gallon today. I wish I had thought about it before I did it since they are in one of my oldest tanks with lots of scratches on the glass. Here are pics of 2 of my 3 new babies:

The crays look good even with the sratches on the tank. Do they keep this coloration as adults?

Thanks

I don't know if they keep this coloration or not since these are the first marble crayfish I've ever had. I do know that one of them was a much darker brown last night. I think it mostly depends on the type of lighting they have as to the color they will be.