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Crayfish ID and some not growing


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#1 kaliska

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Posted 31 August 2016 - 12:16 PM

At the time I was completely sure these were Cambarus diogenes and completely legal to collect, I've caught crays there before and saw an adult male and 2 adult females, and this doesn't fit in any of the fish discussion sections above that I could see.  Maybe I missed it or should have put it in other.  Anyway I caught these in the washed out fossil area south of the coralville spillway where they hide in the slow run off under rock ledges where mud collects and to just repost what I have on the other natives forum:

 

I caught a bunch of these guys months back. They were about half this size. These have stopped growing though. I separated them out as falling behind the others from the same pool in the rocks along a stream and with the same coloring of blues and browns with a bit of dark red. The others come nowhere near fitting in these tubes anymore. They get New life spectrum algae pellets, brine shrimp flakes, I rotate 2 other brands of algae wafers that are more carnivorous than NLS, the occasionally caught guppy, some excess snails, some vegetables or aquatic plant matter.... I added crushed coral to my invert tanks because I was having shell issues and a lot of lost front claws on molt but they've stayed the same size while slowing down molting at the same speed as their larger counter parts. I am guessing them to be devil crayfish. If someone could confirm and are they just the weak ones that would have been eaten? Slow growing females? I haven't tried to confirm gender. I have culled down to 2 males and 2 females from the ones that kept growing. These 5 are living in this tank with tubes and lava rock with only some posturing over food.

 

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The bigger ones before they got even bigger

 

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#2 centrarchid

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Posted 31 August 2016 - 01:14 PM

Images not best but the appear to be Orconectes rusticus.  Crayfish (lower right) in upper pick appears to be getting ready to peal.  By this time both sexes should be going form I which will cease growth normally through next spring if natural photo and temperature regime are followed.  Indoors they will stay form I for a month or so then go to form II.


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#3 Matt DeLaVega

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Posted 01 September 2016 - 08:19 AM

If the crayfish in the bottom photo is what they all look like, with that rusty brown spot on the side of the carapace, then they are rusty crayfish.

 

Isn't diogenes a burrower? Chimney builder?


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#4 centrarchid

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Posted 01 September 2016 - 10:42 AM

I suspect diogenes should not apply to any crayfish occurring in Iowa.  They belong to the same devil crayfish group but not that actual species.


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#5 kaliska

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Posted 01 September 2016 - 05:25 PM

We have burrowing chimney builders that look like the pics of diogenes.  I've seen them before and I saw them recently being uncovered by a lake being drained with sadly dead bodies everywhere but it's not possible to leave a trap overnight there or to get to them by hand. I thought diogenes were quite widespread but perhaps it is another similar species?  A few of these have shown red claw tips between molts but someone said that can happen of various Northern versions of species.  These were not in the best burrowing location but their habitat has changed drastically over the years because it was created during the huge flood where most of Iowa was underwater and this spot got blasted by a river of water that went over the spillway.  The area was mud bottomed pools sometimes 10' deep between fossil filled rocks that had been uncovered connecting to a sand and mud bottom reservoir outflow.  However, human intervention to recover the nearby structures and natural changes have drained the lower pools with mud bottoms and left the crayfish in places where the water backs up under rock ledges that hide mud.  The fish that were in the area as food have been replaced with mostly tadpoles.  There was a nice tree frog tadpole raising area but the constant running water hidden by the trees has dried up to a path people walk.  I suspect in another couple years this area will be home to nothing but toads and their tadpoles during heavy rains while everything relocates back to the main waters again.

What I'd like is a tank with a breeding pair/trio of big, bulky clawed crays that move things around a lot so they are interesting to watch. These seem to be fulfilling that so far.  I like some of the potential colors of diogenes better though.  Maybe today we'll check the progress of that lake again.  The plant life had exploded too much to find burrows under the clear water the last time but the time before that was definitely huge chimney building burrowers hanging out in front of their holes for food opportunities.



#6 kaliska

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Posted 01 September 2016 - 06:45 PM

IUCN lists cambarus diogenes as iowa, Illinois, Wisconsin, and Michigan to name a few local states on the list. northern range is parts of Canada. So they should exist and it just depends which individuals I might be identifying.

#7 centrarchid

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Posted 01 September 2016 - 08:23 PM

The type locality for C. diogenes is a long way off, east coast I believe.  More than two between your location and the type locality have already been split out with two occurring in Illinois.  Yours more likely to be C. nebraskaensis.  C. nebraskaensis is what appears to be in MO even though it is listed as C. diogenes.  What I think you have appears much more brown than C. diogenes.


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#8 Matt DeLaVega

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Posted 01 September 2016 - 11:54 PM

The last photo is of rusticus. Again, if that is what all of your crayfish look like, I can't tell due to the photo quality, that is the species you have. If others are different, I do not know. But I would bet my bottom dollar that the last photo is a rusty.


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#9 centrarchid

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Posted 02 September 2016 - 05:56 AM

Rustys are the only crayfish up that way having a brownish body and nearly blue legs.


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#10 kaliska

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Posted 02 September 2016 - 04:09 PM

I tried to go back and find adults but it's too cool here already.  They've gone deep.  I did find that even minnows are still living under that rock ledge.  Given other structures in the area I think this lower half of the rock area is being fed from underground and may either have an underground spring or reach the water table of the lake and the rock shelf goes back 10' minimum.  Possibly the entire area which would be 50'+.  There were more tiny crayfish hanging about and a few medium plain brown but not the big colorful male even with some bait thrown in the water.  Just the minnows.  Maybe this particular spot will last despite the rest drying up. 

 

What are the odds of finding orconectes virilis?  Are they always rustys with blue legs?  I do have one with very blue legs and the website I have been looking at (which does say diogenes is in the northern midwest) says they are native with the rusty taking over some of their territory it didn't used to.  It also says rustys are an introduced species to Iowa.



#11 Matt DeLaVega

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Posted 02 September 2016 - 05:33 PM

Many rustys have a large amount of blue/green, but not always. I would not use it as a primary ID character.


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#12 centrarchid

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Posted 03 September 2016 - 04:18 AM

I am not using it as a primary ID character because happen to know a little about Rusty Crayfish from throughout its range, natural and otherwise.

 

Which others have the blue legs up there?  Additionally have you seen "Rusty's" up there with legs not blue of blue-green and then differing to form I gonopods to assign to species?


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#13 Matt DeLaVega

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Posted 03 September 2016 - 01:20 PM

I am not using it as a primary ID character because happen to know a little about Rusty Crayfish from throughout its range, natural and otherwise.

 

Which others have the blue legs up there?  Additionally have you seen "Rusty's" up there with legs not blue of blue-green and then differing to form I gonopods to assign to species?

 

 I was not referring to you.

 

I was referring to this.

 

 

"What are the odds of finding orconectes virilis?  Are they always rustys with blue legs?  I do have one with very blue legs and the website I have been looking at (which does say diogenes is in the northern midwest) says they are native with the rusty taking over some of their territory it didn't used to.  It also says rustys are an introduced species to Iowa."


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#14 centrarchid

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Posted 03 September 2016 - 02:41 PM

 

 I was not referring to you.

 

I was referring to this.

 

 

"What are the odds of finding orconectes virilis?  Are they always rustys with blue legs?  I do have one with very blue legs and the website I have been looking at (which does say diogenes is in the northern midwest) says they are native with the rusty taking over some of their territory it didn't used to.  It also says rustys are an introduced species to Iowa."

What many are still calling C. diogenes up there has very little overlap with Rusty Crayfish in terms of microhabitat.   All the critters they are splitting out of C. diogenes are primary burrowers which are more terestrial than all the Orconectes spp which are tertiary burrowers.  What I would be more comfortable saying the Rusty is displacing Golden Cray Orconectes luteus as they two species overlap in in about every manner you can think of with the former still expanding its range into the latter's northern range. 


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