4/22/2014
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.
Fish Dichotomous Key Answers
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
Rock Bass (Redeye)
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4/22/2014
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
Channel Catfish
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
2
4/22/2014
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
Bluegill
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
3
4/22/2014
Slightly
Indented
Caudal.
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
Chain Pickerel
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
4
4/22/2014
American Eel
This is a Redbreast. It is NOT on the
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
Anterior-front
Posterior-rear
Dorsal-top
key ;)
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
5
4/22/2014
Largemouth Bass
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
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
6
4/22/2014
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
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….
7
4/22/2014
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
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
8
4/22/2014
Walleye
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
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
BlackCrappie
White Crappie
9
4/22/2014
This is a Blue Catfish….
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
Salamander Dichotomous Key Answers
Siren
Mudpuppy
Over 7 cm.
Spotted
Salamander
Over 7 cm.
Marbled
Salamander
Red-backed
Salamander
Tiger
Salamander
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4/22/2014
Salamanders (Answer Key)
1. Plethodon glutinosus, slimy salamander
2. Ambystoma jeffersonianum , Jefferson salamander
3. Ambystoma maculatum , spotted salamander
4. Triturus viridescens, newt
5.Eurycea bislineata, two-lined salmander
6.Necturus maculosism, mudd puppy
7. Ambystoma tigrinum, tiger salamander
8. Hemidactylium scutatum, tour-toed salamander
9. Plethodon cinereus, red-backed salamander
10. Siren intermedia, siren Siren intermedia
11. Ambystoma opacum, marbled salamander
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4/22/2014
Arachnid Dichotomous Key
Answers
A
Microwhip
Scorpion
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B
•Segmented abdomen
•No tail
•Abdomen much larger than
cephalothorax
•Pedipalps much shorter than legs
Daddy Long Legs
Scorpion
C
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Pedipalps
Wind Scorpion
D
Segmented abdomen.
Abdomen larger than cephalothorax.
Pedipalps about the same size as
legs.
No pincers on pedipalps
E
Cephalothorax and abdomen
join here
Mite
-no segmented
cephalothorax or abdomen.
-Spines
Size of a pencil point
-
14
4/22/2014
F
Whip spiders
-Segmented abdomen
-No tail
-First leg
Tick
G
-no segmented abdomen
or ceph.
-no narrowing where
abdomen and
cephalothorax meet.
15
4/22/2014
Sea Spider
H
-segmented cephalothorax
-abdomen much smaller than
cephalothorax
Abdomen NOT
segmented
Argiope
I
Abdomen (narrowing at
waist)
Some hair on cephalothroax
but not on abdomen
Cephalothorax
tiny pedipalps
16
4/22/2014
J
- NO segmented
abdomen or
cephalothorax
-narrow “waist.”
-pedipalps slightly shorter
than legs
Curved pedipalps
Jumping Spider
K
Tarantula
-Pedipalps straight
No segmented abdomen or
ceph.
-Narrow waist
17
4/22/2014
pincers
Whip Scorpion
pedipalps
-no stinger on tip of tail.
-large
L
Trapdoor Spider
Plated cephalothorax
Thick, tight jaws
M
pedipalps
18
4/22/2014
Pseudoscorpion
pedipalps
19