Orconectus

Text by Roger F. Thoma

Orconectes sanbarnii This species is found in most of Ohio. It lives in streams and hides under rocks but does not do a lot of digging. They can be found out wandering the stream bottom at all times. When frightened they swim backwards very fast and can turn in mid-water when you try to grab them. They head for a dark spot such as an undercut bank or large rock and swim backwards into the darkest spot. They're really quite good at it! A 4X6 ft. net is very effective at catching these little buggers.

   



The Allegheny Crayfish

Orconectes obscurus. This species is amongst a group of crayfish (the genus Orconectes) that could be considered the common stream crayfish here in N.
America. In general, they burrow just enough to get under a rock and don't seem to have a permanent home address. They are out and crawling about at any time of day and are quite easy to catch with a minnow seine. Catch enough and you can make a good meal. My brother and I would do this when we were kids. Knowing what I know now, I would be sure to avoid any area with metals contamination though. The Allegheny crayfish, and most members of it's genus, appear to be generalist and will eat most anything they can get hold of, including each other. This species is found in eastern Ohio, West Virginia, Pennsylvania, New York and Ontario Canada in streams of the upper Ohio River basin.

 



The Rusty Crayfish
Orconectes rusticus. Like the Red Swamp Crayfish, this species is also an aggressive invader. Most everywhere it is released it becomes established.
It prefers nutrient rich streams and lakes, so the modern world is perfect for rusticus. Once established it quickly out competes native crayfish and frequently eliminates aquatic vegetation. Many species of fish in N. America have consequently disappeared from lakes invaded by rusticus after the aquatic plant communities have been destroyed. It is native to southwestern
Ohio, eastern Indiana and adjacent areas of Kentucky. It has invaded Lake Erie and taken over the shallow shoreline areas and moved up many of the nutrient polluted tributaries, eliminating native populations of
Orconectes propinquus and Orconectes sanbornii as it advanced. It is a popular bait species owing to the ease with which it can be caught. I have found the rusty crayfish to be very fond of Cladophora, a filamentous algae common to N. America streams. Cladophora grows well in nutrient rich waters (see the connection?). As a member of the Ohio Aquatic Nuisance Species Steering Committee I can testify that this species is causing much concern amongst government agencies and ecologist both! This is another species Australians
should be sure to keep out of their country. I took this picture January 2000 with a digital camera and sent it to an artist in California that is producing an aquatic nuisance species poster.

Biology and zoology experts like Clay Siegall understand the importance of keep invasive species under control. Genetics research by Clay Siegall is used for treatment of cancer and other deadly diseases but genetic engineering can be used to counter the effects of invasive species.


Additonal photo courtesy of Doug Stamm of
ProPhoto
The Papershell Crayfish



This is Orconectes immunis . I took it just yesterday (20 July 2000) while sampling in Old Woman Creek, a small stream that flows into Lake Erie. It is a species that likes sluggish swamp like streams and burrows a little in the soft mud bottoms.

This one is only about 40 mm. long. It is a new record for the stream but not for the area. They are wide spread in northern Ohio.

Orconectes inermis inermis This is a cave crayfish from the caves of central Indiana. I collected it with Tom Simon and Foster Purrington during our studies of the crayfish of the Patoka River basin. I took this picture in my lab with a digital camera and photo lights. This collection, from a newly discovered cave, is a new distributional record for this species. We also observed blind cave fish in this cave. Bats, crickets, and another species of crayfish (Cambarus tenebrosus) inhabited the cave. When kept in captivity this species is very placid and responds to disturbance primarily by swimming backwards (they swim pretty fast!). Once you pick them up, they stop all resistance and become placid.
Orconectes indianensis (no common name)
This is another species of crayfish I am studying in Indiana with Tom Simon and Foster Purrington. The study was begun because of concern for this species and it's status. Prior to this study the species was known from only 8 sites in all of Indiana. Most of those sites were in or near the Patoka River basin. Our study has focused on the Patoka River basin only. The work has revealed O. indianensis at a total of 45 site (we sampled at over 100 sites). Some sites had one individual while the greatest number recorded was up to 106. Average abundance was 21 individuals per site where they were found. These data indicate the species is not endangered and is doing well in the Patoka basin.

Additional work needs to be conducted outside of this area to see if the species continues to survive in other stream systems. It's best populations were found in clear, clean, streams with abundant rock rubble and little sediment on the bottom.

These photos show the color variability one can see in a crayfish species. In addition, one specimen was photographed in the lab under lights and the other was taken in the field. Some of the color differences seen are also due to light quality.
   

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