What kind of key cannot unlock a thing? A Dichotomous Key
Dec 16, 2015
Dichotomous Keys
• A dichotomous key is a tool that allows the user to determine the identity of items in the natural world, such as trees, wildflowers, mammals, reptiles, rocks, and fish.
• "Dichotomous" means "divided into two parts". Therefore, dichotomous keys always give two choices in each step.
1 With flower.Without flower
AngiospermsGo to 2
2 Seedless.Seed bearing
Go to 3Gymnosperms
3 Plant body do not differentiated into root,stem and leaves.Plant body differentiated into root, stem andleaves
Go to 4
Go to 5
4 Without photosynthetic pigment.With chlorophyll or other photosyntheticpigment
AlgaeFungi
5 No vascular tissues.With vascular tissues
MossesFern
Example of a dichotomous key…
Traditional format
Dichotomous key
N o n -flo w e rin g p la n ts
W ith o u t p h o tsyn -th e tic p ig m e n t
W ith c h lo ro p h yll o ro th e r p h o to syn th e ticp ig m e n t
A lg a e Fu n g i
N o v a sc u la r tissu e s
W ith va sc u la rtissu e s
M o sse s G ym n o sp e rm s
P la n t b o d y n o td iff e re n tia te d in toro o t, ste m a n d le a v e s
P la n t b o d yd iff e re n tia te din to ste m a n d le a v e s
Se e d le ss Se e d -b e a rin g
Fe rn s
F lo w e rin g P la n ts(A n g io sp e rm )
W ith o u t flo w e rW ith flo w e r
P la n ts
1a. With a hole Go to Question 2
1b. Without a hole Go to Question 3
2a. Six sided It is Species #1
2b. Four sided It is Species #6
3a. With threading Go to Question 4
3b. Without threading It is Species #8
4a. Pointy tip Go to Question 5
4b. No pointy tip Go to Question 6
5a. Rounded head It is Species #4
5b. Not rounded head It is Species #7
6a. Flat head Go to Question 7
6b. Not flat head It is Species #2
7a. Body length twice the width of head
It is Species #5
7b. Body length not twice the width of head
It is Species #3
Let’s Practice……..Which bird is the Certhidea?Which bird is the Platyspiza?Which bird is the Geospiza?Which bird is the Camarhynchus?
Guided Practice
A. Beverlus B. Dallus C.Rajus D. Kentuckyus
E. Californus F. Walawala G. Dakotas H. Yorkius
Cooperative Group Practice- Complete Norms ID in crews.Answers to Dichotomous Key on Norms
REMEMBER- the objective is to work together to complete the task. Giving answers is to crew members is not acceptable. Help struggling crew members by showing them HOW to identify the Norm rather then by simply giveingthem the answer.
Dichotomous Key Independent Practice
Identify the fish using a dichotomous key. Teacher needs to hand out the
dry erase markers and white boards.
Now use the dichotomous key on your table to identify these fish
· Anterior-front· Posterior-rear
· Dorsal-top· Ventral-bottom
· Elongated-stretched out· Concave-bowed in (like the mark in the grass if you
drop a cannon ball)· Convex-bowed out
· Barbels- whiskers· Caudal-tail
Fish #1
Rock Bass (Redeye)
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Fish #2
· Anterior-front· Posterior-rear
· Dorsal-top· Ventral-bottom
· Elongated-stretched out· Concave-bowed in (like the mark in the grass if you
drop a cannon ball)· Convex-bowed out
· Barbels- whiskers· Caudal-tail
Brook Trout
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· Anterior-front· Posterior-rear
· Dorsal-top· Ventral-bottom
· Elongated-stretched out· Concave-bowed in (like the mark in the grass if you
drop a cannon ball)· Convex-bowed out
· Barbels- whiskers· Caudal-tail
Channel Catfish90603010
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Concave forehead
· Anterior-front· Posterior-rear
· Dorsal-top· Ventral-bottom
· Elongated-stretched out· Concave-bowed in (like the mark in the grass if you
drop a cannon ball)· Convex-bowed out
· Barbels- whiskers· Caudal-tail
Yellow Perch
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· Anterior-front· Posterior-rear
· Dorsal-top· Ventral-bottom
· Elongated-stretched out· Concave-bowed in (like the mark in the grass if you
drop a cannon ball)· Convex-bowed out
· Barbels- whiskers· Caudal-tail
This is a Mad Tom catfish. They only grow a few inches in length. They are NOT on the key….
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Fully grown 5 inch adult……..
· Anterior-front· Posterior-rear
· Dorsal-top· Ventral-bottom
· Elongated-stretched out· Concave-bowed in (like the mark in the grass if you
drop a cannon ball)· Convex-bowed out
· Barbels- whiskers· Caudal-tail
Bluegill
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· Anterior-front· Posterior-rear
· Dorsal-top· Ventral-bottom
· Elongated-stretched out· Concave-bowed in (like the mark in the grass if you
drop a cannon ball)· Convex-bowed out
· Barbels- whiskers· Caudal-tail
Bullhead Catfish
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SlightlyIndentedCaudal.
· Anterior-front· Posterior-rear
· Dorsal-top· Ventral-bottom
· Elongated-stretched out· Concave-bowed in (like the mark in the grass if you
drop a cannon ball)· Convex-bowed out
· Barbels- whiskers· Caudal-tail
Chain Pickerel
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· Anterior-front· Posterior-rear
· Dorsal-top· Ventral-bottom
· Elongated-stretched out· Concave-bowed in (like the mark in the grass if you
drop a cannon ball)· Convex-bowed out
· Barbels- whiskers· Caudal-tail
American Eel
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· Anterior-front· Posterior-rear
· Dorsal-top· Ventral-bottom
· Elongated-stretched out· Concave-bowed in (like the mark in the grass if you
drop a cannon ball)· Convex-bowed out
· Barbels- whiskers· Caudal-tail
This is a Redbreast. It is NOT on the key ;)
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· Anterior-front· Posterior-rear
· Dorsal-top· Ventral-bottom
· Elongated-stretched out· Concave-bowed in (like the mark in the grass if you
drop a cannon ball)· Convex-bowed out
· Barbels- whiskers· Caudal-tail
Largemouth Bass90603010
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· Anterior-front· Posterior-rear
· Dorsal-top· Ventral-bottom
· Elongated-stretched out· Concave-bowed in (like the mark in the grass if you
drop a cannon ball)· Convex-bowed out
· Barbels- whiskers· Caudal-tail
Northern Pike
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· Anterior-front· Posterior-rear
· Dorsal-top· Ventral-bottom
· Elongated-stretched out· Concave-bowed in (like the mark in the grass if you
drop a cannon ball)· Convex-bowed out
· Barbels- whiskers· Caudal-tail
Rainbow Trout
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· Anterior-front· Posterior-rear
· Dorsal-top· Ventral-bottom
· Elongated-stretched out· Concave-bowed in (like the mark in
the grass if you drop a cannon ball)· Convex-bowed out
· Barbels- whiskers· Caudal-tail
White Suckah…Sucker….
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· Anterior-front· Posterior-rear
· Dorsal-top· Ventral-bottom
· Elongated-stretched out· Concave-bowed in (like the mark in the grass if you drop a cannon
ball)· Convex-bowed out
· Barbels- whiskers· Caudal-tail
This is a Black Crappie (pronounce “Crop’-ee”) and it isn’t on the key…
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· Anterior-front· Posterior-rear
· Dorsal-top· Ventral-bottom
· Elongated-stretched out· Concave-bowed in (like the mark in the grass if you
drop a cannon ball)· Convex-bowed out
· Barbels- whiskers· Caudal-tail
Carp
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· Anterior-front· Posterior-rear
· Dorsal-top· Ventral-bottom
· Elongated-stretched out· Concave-bowed in (like the mark in the grass if you
drop a cannon ball)· Convex-bowed out
· Barbels- whiskers· Caudal-tail
Smallmouth Bass
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· Anterior-front· Posterior-rear
· Dorsal-top· Ventral-bottom
· Elongated-stretched out· Concave-bowed in (like the mark in the grass if you
drop a cannon ball)· Convex-bowed out
· Barbels- whiskers· Caudal-tail
Walleye
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· Anterior-front· Posterior-rear
· Dorsal-top· Ventral-bottom
· Elongated-stretched out· Concave-bowed in (like the mark in the grass if you
drop a cannon ball)· Convex-bowed out
· Barbels- whiskers· Caudal-tail
White Crappie
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· Anterior-front· Posterior-rear
· Dorsal-top· Ventral-bottom
· Elongated-stretched out· Concave-bowed in (like the mark in the grass if you
drop a cannon ball)· Convex-bowed out
· Barbels- whiskers· Caudal-tail
This is a Bowfin or “Mudfish,” and it isn’t on the key….
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· Anterior-front· Posterior-rear
· Dorsal-top· Ventral-bottom
· Elongated-stretched out· Concave-bowed in (like the mark in the grass if you
drop a cannon ball)· Convex-bowed out
· Barbels- whiskers· Caudal-tail
This is a Blue Catfish….
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Opening/Closing-
Using your Pamishan Dichotomous Key homework sheet, identify this Pamishan.
Narrowus wolfus
Walk-thru example…
1. What tool is used to help identify and classify organisms?A dichotomous key.
2. How many options are there for each number in this tool?two
3. Use the Pamishan dichtomous key to determine which Pamishan is shown here.This is number 10, Broadus emmus.
Opening/Closing
Pamishan Creatures Activity OneIndependent Practice (OPTIONAL)-Each of you will be assigned a number for a Pamishan Alien and a dichotomous key (do NOT write on either one.) Use the dichotomous key to identify your Pamishan Alien.
Pamishan Creatures Activity TwoIndependent PracticeIdentify the Pamishan Aliens. OWs will use Crew Drill Tally sheet to record incorrect responses for each crew member (#1-10 only.) Boatswain will ensure answers are reported accurately.
Pamishan Alien Dichotomous Key answers
1. Narrowus portus2. Broadus archus3. Narrowus plainus4. Broadus hairyemus5. Broadus hairus6. Broadus anderscus7. Narrowus montanus8. Narrowus georgius9. Narrowus blankus10. Broadus emmus
11. Narrowus cyclops12. Broadus hairystus13. Narrowus beardus14. Broadus walter15. Broadus plainus16. Broadus kiferus 17. Narrowus starbops18. Broadus tritops19. Narrowus wolfus20. Narrowus fuzzus
Salamanders:
Use your handout to identify these salamanders
14
2
3
5
6
Independent PRACTICE
Over 7 cm.
Over 7 cm.
Siren
Spotted Salamander
Mudpuppy
MarbledSalamander
Tiger Salamander
Red-backed Salamander
1. A __________________ is a tool used to help identify and classify organisms.
2. What is this organism?This is number 1, Narrowusportus.
Opening/Closingdichotomous key
3. What is this organism?This is a two-linedSalamander.
Use the Pamishan key in the vinyl sleeve.
Use the salamanders key.
No external gills
Hind legs
Key will say spikes on left leg. That is YOUR left as you are looking at it.
Less than 7 cm.
Daddy Long Legs
•Segmented abdomen•No tail•Abdomen much larger than cephalothorax•Pedipalps much shorter than legs
B
Wind Scorpion
Segmented abdomen.Abdomen larger than cephalothorax.Pedipalps about the same size as legs.No pincers on pedipalps
Pedipalps
D
Mite
-no segmented cephalothorax or abdomen.-SpinesSize of a pencil point-
Cephalothorax and abdomen join here
E
Argiope
I
Cephalothorax
Abdomen (narrowing at waist)
tiny pedipalps
Abdomen NOT segmented
Some hair on cephalothroax but not on abdomen
Jumping Spider
J- NO segmented abdomen or cephalothorax-narrow “waist.”-pedipalps slightly shorter than legs
Curved pedipalps
Abdomen has more than 6 segments
Abdomen does not “split” or fork and does not have any kind of tail. Using the Insect Dichtomous Key to
identify the order of this insect.
Order Phasmatodea- Walking Stick
Eyes located on sides of head
Order Thysanura- Silverfish.
Using the Insect Dichtomous Key to identify the order of this insect.
Use the Dichotomous Key for Stream Animals to Identify
Mayfly Larva
Single hook on end of each appendage (leg)
Tails are “thin.”
Use the Dichotomous Key for Stream Animals to Identify
Dragonfly Nymph Three short points, but no tails.
Use Cedar Glade Flowers Key
A “daisy-like” flower would be similar to this. Multiple, long, slender petals.