Observing &
Collecting Crayfish
Crayfish in their Natural Habitat
Crayfish are found in many streams and lakes of the Pacific
Northwest. This provides teachers the opportunity to observe
crayfish in their natural environment, or collect their own
teaching specimens.
Crayfish use rocks, wood or clumps of vegetation to hide from
predators, especially during the day when they are less active.
Look for them in areas of a stream where the water flow is not
too rapid. The largest ones will prefer to hide under larger
structures, such as big rocks.
Many things can motivate a teacher to
prefer working with animals in their natural
habitat. The educational merits of students
learning outdoors are compelling. Student
motivation and achievement soars, and
observing animals in their own habitat
enhances the opportunities for in-depth
understanding.
For some, ethical considerations drive the
desire to humanely observe the animals in
their natural habitat, particularly since all
living specimens that are taken into a
classroom setting must be disposed of and
never returned to their environment.
Collecting Crayfish
Crayfish can be caught by hand by carefully grasping them
behind their claws around the carapace (shell of the body). Of
course, this process is likely to be much easier when they have
been first captured in a net.
D-frame nets or short seine nets can be held immediately
downstream of likely crayfish habitat. Disturb the streambed by
kicking or flipping over and rubbing the rocks, flushing
everything downstream. The crayfish will be swept or “tail-flip”
themselves backwards into the net. Lift the net quickly!
Crayfish habitats dominated by aquatic plants or leaf litter are
easily sampled by sweeping the net through the vegetation.
Recently it was discovered that the import
of non-native crayfish from other US
regions for school studies has resulted in
their invasion into local streams when
released instead of disposed of properly.
Observing in the stream habitat eliminates
the need to import potentially nuisance
species.
Many schools do have suitable streams
nearby, and not having to purchase
crayfish saves money and the
inconvenience of maintaining them in the
classroom.
Resources
Observing in the Field
Field
Taking FOSS Outdoors Folio
http://www.fossweb.com/pdfs/Taking_FOSS_Out
_101011.pdf
Science in the Schoolyard Guide:
FOSS® Structures of Life
http://www.fossweb.com/modules36/pdfs/StructuresofLife/Structures_Life_Science_
Outdoors.pdf
Crayfish Care and Handling
http://www.k12.wa.us/Science/Resources.aspx
Crayfish Invasion Video
Dishtrays, buckets or other plastic containers make nice
ourtdoor observation stations. Place a number of crayfish
and some rocks or leaves in the container, and students
can easily observe just as in the classrom. Other stream
invertebrate “bugs” will likely also be present, providing lots
of additional excitement. (See Resources for a key to
benthic macroinvertebrates.) Multiple containers will allow
students to observe in small groups and the opportunity to
compare differences in behavior and habitat use. When
finished, students can gently release all the collected
materials back to the stream.
Back to the Classroom…or Not?
Not?
http://www.opb.org/programs/ofg/segments/view/
1777
Brief Guide to Crayfish Identification
in the Pacific Northwest
http://wdfw.wa.gov/fishing/shellfish/crayfish/crayfis
h_id_guide.pdf
Invasive Crayfish Information
http://www.invasivespecies.wa.gov/documents/pri
orities/Crayfishfactsheet.pdf
Washington State Invasive Species
Council
http://www.invasivespecies.wa.gov
National Invasive Species Information
Center
http://www.invasivespeciesinfo.gov
Aquatic Invasive Species Curriculum
http://seagrant.oregonstate.edu/invasive-species
Full Color Macroinvertebrate
Identification Key
http://www.nwnature.net/macros
Crayfish can be brought back to the classroom, assuming a
proper habitat has been set up for them prior to collection.
Transporting crayfish is fairly simple, as long as it is done
promptly. They are resilient and do fine in a container of
water or a box filled with wet moss. (They tend to puncture
plastic bags.) Crayfish are quite adept at escaping, but be
careful to not secure their container so well that they do not
have air flow. Keeping them cool is critical.
Crayfish brought into the classroom must not ever be
released back into the environment, Complete care and
disposal instuctions for crayfish are available at
http://www.k12.wa.us/Science/Resources.aspx
What to do if you find a nonnon-native invasive
crayfish?
Make it a teachable moment! The first thing to do is to call
1‐‐877‐‐9‐‐INFEST or report online at
www.InvasiveSpecies.wa.gov
Your students can then contribute to the science
community’s efforts to understand the status of crayfish in
northwest streams. Take detailed photographs of the
crayfish, or preserve the specimen in alcohol, and contact:
Julian D. Olden
School of Aquatic and Fishery Sciences
University of Washington
Seattle WA 98195
e‐mail: [email protected]
BriefGuidetoCrayfishIdentificationinthePacificNorthwest
December2009
Signalcrayfish(Pacifasticusleniusculus)
Washingtonhasonlyonenativecrayfishspecies,thesignalcrayfish.Itisfairlyeasily
identifiedbyitsuniformbrownishorblueͲtingedcolorationasadultswithawhiteband
atthejointoftheclaws(chelae).Juvenilesofthesignalcrayfishwilllikelybedrabbrown
withthewhitebandlessnoticeable.Itisalsoquitesmoothonallitssurfacescompared
toothercrayfish,especiallytheclaw.
Redswampcrayfish(Procambarusclarkii)
Theinvasiveredswampcrayfishwillberedasadultswithlonger,narrowerclawsthan
thesignalcrayfish.Additionally,redswampcrayfishclawswillbecoveredwithred,
whiteorblackbumps(tubercules).Redswampjuvenileswillbebrownbutwithabody
shapeandpatternsimilartoadults,includingablack“V”patternonthedorsalsideof
thetail(abdomen)andasaltandpepperpatternofspottinginblack,grey,whiteorred
overthecarapace.
SIGNALCRAYFISH REDSWAMPCRAYFISH
Northerncrayfish(Orconectesvirilis)
Thenortherncrayfishisamediumtolargecrayfishandisdistinguishedfromsignaland
redswampcrayfishbybroadflattenedtuberculate(i.e.,largetubercules)claws,anda
oliveͲbrownbodythatisdappledwithdarkbrown,andabdominalsegmentswithdark
brownmedialspots.
Rustycrayfish(Orconectesrusticus)
Theinvasiverustycrayfish,amajornuisancespeciesinthemidwestUnitedStatesand
elsewhere,wasrecentlyfoundintheJohnDayRiverofOregon(Oldenetal.2009).The
speciesisnotyetknownfromothersitesinthePacificNorthwest.Rustycrayfishmaybe
bestidentifiedbytherustcoloredspotoneachsideofthecarapacenearthejointwith
theabdomen(seefigures).Rustycrayfishalsofrequentlyhaveblacktipstotheirclaws.
RustycrayfishbelongtothesamegenusasOrconectesvirilis,buttheirclawsare
generallysmoother–althoughmaystillhavetubercules/bumpsincontrasttothenative
signalcrayfish.
Crayfishthatdonotconformtothesedescriptionscouldbeotherspeciessuchasthe
ringedcrayfishOrconectesneglectusorthewhiterivercrayfishProcambarusacutus.
PLEASEPHOTOGRAPHANYCRAYFISHTHATYOUARENOTABLETOIDENTIFY.
PLEASEKEEPVOUCHERSPECIMENSOFANYNONͲNATIVECRAYFISH(depositinethanol).
GettingYourSpecimenstotheUniversityofWashington
Onceyouhavecollectedsomenonnativespecimens,I’dliketomakearrangementsto
getthemtoUW.Pleasegivemeacall:
JulianD.Olden,Ph.D.
AssistantProfessor
SchoolofAquaticandFisherySciences
UniversityofWashington
Box355020;SeattleWA98195
eͲmail:[email protected]
phone:206Ͳ616Ͳ3112
web:http://www.fish.washington.edu/research/oldenlab/
skype:goldenolden