Date: ____________________
Biology
Name: __________________________
Taxonomy and Phylogeny Lab
Introduction:
Taxonomy is used by biologists to name and classify all the various different species on the
planet. The process of identifying organisms is difficult because there are so many of them. One of the
tools used in biological identification is called a KEY. There are a number of different kinds of keys. The
one we will use here is called a Dichotomous Key. The word dichotomous means “separating into two
pairs,” and it describes the kind of choices you must make in using such a key.
Objectives:


Identify characteristics of organisms that are helpful in classification
Introduction to the use of a Dichotomous Key
Domain →
Eukarya
Kingdom →
Animalia
Figure 1: Human Taxonomic Classification
Phylum → Class →
Order → Family →
Chordata
Mammalia Primates Hominidae
Genus →
Homo
Species
sapiens
Vocabulary for Taxonomy Lab
Radial symmetry
Invertebrate vs.
vertebrate
Exoskeleton
Cartilaginous vs.
bony skeleton
Segmented
Antennae
Tentacles
Jointed legs
Procedure:
1. You will find several numbered stations arranged around the room with labeled common names of
various species. Listen to your teacher about how to switch stations. MAKE SURE that you write the
correct labeled common names in Chart 1.
2. Place the common name in the space next to its number in Chart 1.
3. Use your Dichotomous Keys 1, 2 or 3 to go through the characteristics of your specimen.
4. Record in Chart 1 under “Dichotomous key steps” the steps you took to find the Phylum and/or
Class of your specimen (e.g. 1a., 2b.)
5. Record in Chart 1 correct Phylum for your specimen. If your specimen falls under either Phylum
Chordata or Arthropoda also record its Class in Chart 1.
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Key 1: Dichotomous Key to selected Invertebrate Phyla – For Organisms 1-10
1a. Body Symmetry radial………………………………… go to 2
1b. Body Symmetry not radial…………………………….. go to 3
2a. Tentacles present, soft body…………………… Phylum Coelenterata
2b. Tentacles absent……………………………….. Phylum Echinodermata
3a. Exoskeleton present…………………………………… go to 4
3b. Exoskeleton absent……………………………………. go to 5
4a. Jointed legs present……………………………. Phylum Arthropoda (go to Key 3)
4b. Jointed legs absent……………………………... Phylum Mollusca
5a. Body segmented……………………………………….. Phylum Annelida
5b. Body not segmented…………………………………… Phylum Platyhelminthes
Key 2: Dichotomous Key to the Classes of the Phylum Chordata – For Organisms 11-16
1a. Hairs present…………………………………………… Class Mammalia
1b. Hairs absent……………………………………………. go to 2
2a. Feathers present………………………………... Class Aves
2b. Feathers absent………………………………… go to 3
3a. Jaws present……………………………………………. go to 4
3b. Jaws absent…………………………………………….. Class Agnatha
4a. Paired fins present……………………………… go to 5
4b. Paired fins absent………………………………. go to 6
5a. Skeleton bony…………………………………………... Class Osteichthyes
5b. Skeleton cartilaginous………………………………….. Class Chondrichthyes
6a. scales present…………………………………… Class Reptilia
6b. scales absent……………………………………. Class Amphibia
Key 3: Dichotomous Key to the Classes of the Phylum Arthropoda
1a. Walking legs, more than 5 pairs……………………….. go to 2
1b. Walking legs, 5 or fewer pairs…………………………. go to 3
2a. Legs, 1 pair per body segment…………………. Class Chilopoda
2b. Legs, 2 pairs per body segment…………………Class Diplopoda
3a. Antennae present……………………………………….. go to 4
3b. Antennae absent………………………………………... Class Arachnida
4a. Antennae, 1 pair………………………………... Class Insecta
4b. Antennae, more than 1 pair…………………….. Class Crustacea
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Taxonomy Chart 1
#
Organism common
name
Dichotomous key
steps
Phylum
Class
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
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Analysis Questions:
1. Use Keys 2 and 3 to figure out which Class the following organism description would be
classified under.
a. A hairless organism that has no feathers. A jaw is present and paired fins. After
dissection the scientist notices a bony skeleton. ___________________________
b. This organism has many legs but not more than 3 pairs. Only one pair of antennae
is present. ___________________________
c. This organism has a backbone and is hairy. It has two pair of limbs and through
dissection the scientist observes a bony skeleton. __________________________
d. This organism is warm blooded but not hairy. The outer coat of the organism is
covered in feathers. ___________________________
2. Compare Figure 1 showing human classification from the first page of this lab to Figure 2
below. Explain TWO inferences you can make about the three different organisms listed in
Figure 2 based on Figure 1.
Figure 2: Taxonomic Classification of Three organisms
Domain →
1. Eukarya
2. Eukarya
3. Eukarya
Kingdom →
Animalia
Animalia
Animalia
Phylum →
Chordata
Chordata
Chordata
Class →
Mammalia
Mammalia
Mammalia
Order →
Primates
Primates
Primates
Family →
Hominidae
Hominidae
Hominidae
Genus →
Pan
Pongo
Gorilla
Species
troglodytes
borneo
gorilla
Inference #1: ____________________________________________________________
____________________________________________________________
Inference #2: ____________________________________________________________
____________________________________________________________
3. Pick one characteristic from all of the different species you observed in the lab (Chart 1).
Explain how this characteristic is an adaptation that helps the organism survive.
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
4. Choose two organisms from the different species you observed in the lab (Chart 1) that you
feel might interact in an environment. Describe what you might observe in this interaction.
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
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5. Based upon the basic anatomical differences of the following phyla complete the
phylogenic tree below: coelenterata, annelida, chordata, platyhelminthes & arthropoda.
Remember the further back (to the left) means older and less related.
Phylogenic Tree of Five Animal Phyla
6. Using a specific anatomical feature (e.g. exoskeleton, jointed legs) from the lab, explain
why you chose the phyla for A and B.
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
7. Using a specific anatomical feature (e.g. exoskeleton, jointed legs) from the lab, explain
why you chose the phyla for D and E.
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
8. Explain what “x” represents on the tree? __________________________________________
___________________________________________________________________________
___________________________________________________________________________
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