Crayfish type and sex?

[Hrochnick]

Hi everyone,

Just signed up a I need a little help. I bought my first crayfish the other day, a lovely little blue one and I want to confirm exactly what species and sex it is. It was labelled in the shop as a P. Clarkii and the assistant told me it was female.

However, having read various bits of the internet (esp. here http://www.monsterfishkeepers.com/forums/showthread.php?p=2738545) I have my doubts and I think it may actually be a male P. Allenii - but I'm really not sure...

There should be a few pics attached which hopefully show all the important bits you need for an ID. They were the best I could get yesterday, although the underbelly one is a little blurry, sorry...

So, any ideas? can you help?

Thanks,

Nick.

 

[piggy67]

It is Procambarus alleni.
Notice the areola is very open, indicating its probably P.alleni, also in pic 2 it looks like a clasper by the last leg on the underside which indicates its a male. The longer claws also indicate a male...

here is a good comparison of P.alleni/P.clarkii
http://www.bluecrayfish.com/forum/viewtopic.php?f=9&t=990

BTW...welcome to MFK...

 

[Hrochnick]

Thanks Piggy67, you've confirmed my suspicion. I couldn't (and still can't really on that blurry picture) see any obvious male or female features on the underside, so wanted a confirmation form some experts I'll take another good look when i get home.

Thanks again and happy new year!

 

[black_sun]

That is not a procambarus species. That is a cherax quad, it's an Australian species. You can see the difference in ridges on the head and in the claws (and in the patterning, though that is not to be used as ID method alone). If you wish to sex that species you'll need a very clear shot of the underside, of the last pair of legs and the 3rd pair of legs, since the male's gonopods are very different in Cherax species (it makes males and females look very similar).

 

[black_sun]

It is Procambarus alleni.
Notice the areola is very open, indicating its probably P.alleni, also in pic 2 it looks like a clasper by the last leg on the underside which indicates its a male. The longer claws also indicate a male...

here is a good comparison of P.alleni/P.clarkii
http://www.bluecrayfish.com/forum/viewtopic.php?f=9&t=990

BTW...welcome to MFK...

Piggy,

The areola being open or closed is not to be used as a sole means of identification. A lot of species, in all genus, can have open or closed areola (and in some, a non-existent). This has to be used in conjunction with many other characteristics of the species and genus.

If this were a procambarus species, you'd see very large gonopods running up the underside of the male. This is cherax species, that requires a closer/clearer shot of the underside to view the male's spur like gonopods or female's egg spots.

Finally, longer claws do not indicate whether it is a male or female, as female's can often have longer/larger claws than the males do to male's regenerating their claws from fights. And in some species, longer and tapered claws are a characteristic of the species and not a sexual dimorphic difference in the species.


In your own link, you can see there are drastic differences between the head and carapace ridges, claw/arm texture and shape, body and overall patterning of the species. They are not the same.

 

[piggy67]

Piggy,

The areola being open or closed is not to be used as a sole means of identification. A lot of species, in all genus, can have open or closed areola (and in some, a non-existent). This has to be used in conjunction with many other characteristics of the species and genus.

If this were a procambarus species, you'd see very large gonopods running up the underside of the male. This is cherax species, that requires a closer/clearer shot of the underside to view the male's spur like gonopods or female's egg spots.

Finally, longer claws do not indicate whether it is a male or female, as female's can often have longer/larger claws than the males do to male's regenerating their claws from fights. And in some species, longer and tapered claws are a characteristic of the species and not a sexual dimorphic difference in the species.


In your own link, you can see there are drastic differences between the head and carapace ridges, claw/arm texture and shape, body and overall patterning of the species. They are not the same.

Thank you for pointing that out,black-sun, i still have alot to learn and learning more everyday thanks to MFK and people like you...

 

[Hrochnick]

Hmm, so the plot thickens and the shop were not even close in their labelling. Nice, but no surprise. I'll try and get a better shot of the underside, any chance of a more precise species ID so I know what I've got and what to expect?

Thanks,

 

[Hrochnick]

Actually, you said it right there, didn't you... Cherax Quad. Must pay more attention when reading... stay awake Nick. Sorry...

 

[akaEric]

Identifying a male and female. Look at the 3rd pair of legs. If it has something like 2 holes its a female. And IF I'm not wrong female have a broader body to keep berries. And piggy,
my female has a really long claw. White P. Clarkii

 

[black_sun]

Actually, you said it right there, didn't you... Cherax Quad. Must pay more attention when reading... stay awake Nick. Sorry...

Bwah... I was apparently not awake either, I have a sexing visual guide right in my own forum, d'oh!

Here's a great visual guide I found, you'll be looking at the top set of photos to determine gender in the crayfish:

http://www.crayfishworld.com/sexy.htm