Posts Tagged ‘crayfish’

Crayfish

May 26, 2017

A crayfish was spotted in the shallows of Bull Run, under several inches of water. I estimate it was 3-4 in (~7.6-10.2 cm) in length.

Many crayfish can be particularly hard to identify from a photograph and many new species are still being discovered in Virginia’s waterways. This large crayfish is from the Family Cambaridae and is likely a native species. Other crayfish found in Northern Virginia, like the rusty crayfish (Orconectes rusticus) and red swamp crayfish (Procambarus clarkii), were likely introduced via the food industry and pose a serious threat to native crayfish populations. Source Credit: John Burke, Ecologist III, Stormwater Management Branch, Fairfax County Department of Public Works and Environmental Services.

10 MAY 2017 | Fairfax County, VA | crayfish (underwater)

Notice the first, second, and third pairs of walking legs feature chelae (plural).

A chela /kˈiːlə/, also named claw, nipper, or pincer, is a pincer-like organ terminating certain limbs of some arthropods. The name comes from Greek (χηλή) through New Latin (chela). The plural form is chelae. Legs bearing a chela are called chelipeds. Source Credit: Chela (organ), Wikipedia.

Also notice the slimy stuff on the rocks that makes them super slippery!

The slimy, slippery coating you find on rocks in aquatic systems is periphyton. In freshwater systems, periphyton is mostly comprised of algae but other microorganisms and detritus also collect on submerged rocks. Periphyton serves as an essential food source to many aquatic organisms and can also act as a bioindicator, signaling changes in water chemistry and nutrient levels in the system (Chetelat et al. 1997). Source Credit: John Burke.

Tech Tip:  My Canon 580EX Speedlite external flash unit was set for 1/16 power in order to penetrate the water and illuminate the subject on a bright, sunny day.

Copyright © 2017 Walter Sanford. All rights reserved.

Crayfish

January 15, 2015

Crayfish

Two types of crayfish are known to inhabit the waters at Huntley Meadows Park: a native species; and a non-native species.

We believe our native species is Cambarus diogenes [known as “chimney crayfish”], although we’re not positive about the species. Source Credit: Mr. Kevin Munroe, Park Manager at Huntley Meadows.

The non-native species is “red swamp crayfish” (Procambarus clarkii), according to Ms. Kat Dyer, a long-time volunteer at Huntley Meadows Park also known as the “Crayfish Lady.” Ms. Dyer is now a part-time naturalist at the park.

The crayfish, shown above, was spotted alongside the boardwalk in the hemi-marsh at Huntley Meadows on 24 August 2014. I consulted the local experts for help in identifying the species.

Crayfish are just real hard to ID! You have to have a mature male, and you need to look at the tiny appendages under the abdomen to make a positive ID. My guess is that it’s the [non-native] exotic species since you found it in the wetland rather than in the streams/woods. Source Credit: Kevin Munroe, Park Manager at Huntley Meadows.

Crayfish is an important organism in the wetlands ecosystem food web. Many animals prey upon crayfish, including fish, raccoons, otters, Great Blue Herons, and Great Egrets. Brush shelters (that resemble large, man-made beaver lodges) located in the 50-acre central wetland area provide egg-laying habitat for crayfish.

Copyright © 2015 Walter Sanford. All rights reserved.


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