Zoological Systematics & Taxonomy - Biosciweb.net

Zoological Systematics & Taxonomy 3.1 

Lab #3 - Biological Sciences 102 – Animal Biology 

This lab is designed to introduce you to the basics of animal classification (systematics) and 

taxonomy of animals. This is a field that is constantly changing with the discovery of new 

animals, fossils, scientific techniques and the development of a better understanding of the 

evolutionary relationships between organisms. 

Systematics is the branch of biology that deals with the diversity of organisms in relation to 

their classification. Many biologists and textbooks do not clearly distinguish systematics from 

taxonomy. Thus, systematics is an umbrella term which can encompass many processes that 

describe species. There are at least three important disciplines which are united under this 

broad term. First there is the description of species (identification), there is the naming of 

names (taxonomy) and finally there is the description of the relationships among and between 

taxa (phylogenetics). 

Basically, taxonomy involves the scientific naming of organisms and grouping or 

classifying of them with reference to their position in the kingdoms of life. More than 1.5 

million different species of animals have been classified on the basis of shared derived 

anatomical characters and biochemical procedures such as DNA hybridization, DNA 

microsatellite analyses, and DNA sequence analyses. Most of these species tend to fall into 

certain large groups because of similarities in structural organization. These primary groups 

are known as phyla (singular = phylum). 

How many different animal species currently live on Earth? 

This is not an easy question to answer. There are many regions of the planet that are not wellexplored 

for animal life, in particular, the deep ocean. Some animal species are only found in 

very small areas (eg. less than one square kilometer or less), especially in the tropics. 

Estimates of the total number of all living species generally range from 10 to 100 million (with 

most estimates between 10 and 20 million). More than 1.5 million animals have been 

identified and named with most animals being insects and microscopic life forms. We may 

never know how many different animals there are because many of them have and will become 

extinct before being counted and described. Some zoologists estimate that less than 20% of all 

living animals and less than 1% of animals that existed in the past have been named. 

The tremendous diversity in life today is not new to our planet. The noted evolutionary 

biologist Stephen Jay Gould estimated that 99% of all plant and animal species that have 

existed have already become extinct with most leaving no fossils. Also, realize that humans 

and other large animals are freakishly rare life forms, since 99% of all known animal species 

are smaller than bumble bees. 

Linnaeus and Some History of Classification 

Biologists use a variety of scientific techniques to classify organisms into different categories. 

Most of these procedures judge the varying degrees of apparent similarity and difference that 

they can see from the macroscopic to the microscopic to the molecular level. The assumption 

is that the greater the degree of similarity, the closer the biological and potentially the 

evolutionary relationship.



Today many scientific techniques are used to determine phylogenetic relationships between 

organisms and establish taxonomy of an animal including: 

‣ comparative anatomy or comparative morphology = examines the various shapes 

and sizes of organismal structures, organ systems and their development 

‣ comparative embryology = describes similarities and differences in animal 

development patterns, structures and timing of developmental events 

‣ comparative cytology = looks at variations in cell structures and the number, size and 

shape of chromosomes 

‣ comparative biochemistry = compares the amino acid sequences of proteins and 

nucleotide sequences of DNA 

Before the advent of modern, genetically based evolutionary studies, European and American 

biology consisted primarily of taxonomy, or classification of organisms into different categories 

based on their physical characteristics. The leading naturalists of the 18 th and 19 th centuries 

spent their lives identifying and naming newly discovered plants and animals. However, few of 

them asked what accounted for the patterns of similarities and differences between the 

organisms. This basically non-speculative approach is not surprising since most naturalists 

two centuries ago held the view that plants and animals had been created in their present form 

and that they have remained unchanged. As a result, it made no sense to ask how organisms 

have evolved through time. Similarly, for these early taxonomists, it was inconceivable that 

two animals or plants may have had a common ancestor or that extinct species may have been 

ancestors of modern ones. 

One of the most important 18th century naturalists was a Swedish botanist and medical doctor 

named Carl von Linné (1707-1778). He wrote 180 books mainly describing plant species in 

extreme detail. Since his published writings were mostly in Latin, he is known to the scientific 

world today as Carolus Linnaeus, which is the Latinized form he chose for his name. 

For more biographical information on Linnaeus, review the UC Museum of Paleontology 

at UC Berkeley website at http://www.ucmp.berkeley.edu/history/linnaeus.html. 

Although fundamental classification of animals may predate civilization, the questions of how 

classifications are to be constructed are by no means settled. Linnaeus, in 1735, published 

Systema Naturae. This marks the beginning of the modern classification of plants and 

animals. He devised practical techniques for the naming of groups of organisms and their 

ranking and ordering. He developed the system of binomial nomenclature that we still use 

today. In the modern world there are numerous philosophies and methods of classification 

which are in use and help add to the overall completeness and confusion in the world of 

taxonomy. Linnaeus' great contribution was to provide order in the method used in the 

classification of living organisms. This Linnaean system of classification was widely accepted 

by the early 19th century and is still the basic framework for all taxonomy in the biological 

sciences today. 

The Linnaean system uses two Latin name categories, genus and species, to designate each 

type of organism. A genus is a higher level category that includes one or more species under 

it. Such a dual level designation is referred to as a binomial nomenclature or binomen 

(literally "two names" in Latin). For example, Linnaeus described humans in his system with 

the binomen Homo sapiens, or "man who is wise". Homo is our genus and sapiens is our 

species. 

Linnaeus also created higher, more inclusive classification categories. For instance, he placed 

all monkeys and apes along with humans into the order Primates. His use of the word 

Primates (from the Latin primus meaning "first") reflects the human centered world view of 

Western science during the 18th century. While it implies that humans were "created" first, it



also indicates that people are animals. In terms of our modern understanding of evolution, the 

term “primates” is quite anthropomorphically centric. 

While the form of the Linnaean classification system remains 

substantially the same, the reasoning behind it has undergone 

considerable change. For Linnaeus and his contemporaries, 

taxonomy served to demonstrate the unchanging order inherent in 

the natural world. 

This static view of nature was overturned in science by the middle 

of the 19th century by a small number of radical naturalists, most 

notably Charles Darwin. They provided some of the first conclusive 

evidence that evolution of life forms has occurred. In addition, 

Darwin and Wallace proposed natural selection as the mechanism 

responsible for these changes. 

Late in his life, Linnaeus also began to have some doubts about species being unchanging. 

Crossbreeding resulting in new varieties of plants suggested to him that life forms could 

change somewhat. However, he stopped short of accepting the evolution of one species into 

another. 

How Zoologists and Taxonomists Classify Animals 

On discovering an unknown organism, researchers begin their classification by looking for 

anatomical features that appear to have the same function as those found on other species. 

The next step is determining whether or not the similarities are due to an independent 

evolutionary development or due to descent from a common ancestor. If the latter is the case, 

then the two species are probably closely related and should be classified into the same or near 

biological categories. 

How does one identify an unknown specimen? One way is by direct comparison with 

specimens in a museum reference collection. However, few biologists have ready access to 

such collections and if they do the collections are often incomplete. Even with such access, 

most non-specialists would find this a tedious approach, involving working through thousands 

of museum specimens. In fact, this is part of the foundation of the field of taxonomy. In order 

for scientists and museums to organize their collections, a set of standards was necessary to 

make sense of the incredible diversity of organisms as well as for effective communication 

between biologists. 

A practical alternative is to use a taxonomic key. A key is a convenient tabular device that 

enables us to identify a specimen by comparing it feature by feature with alternatives given in 

key couplets. Keys may be designed to identify species, genera, families, orders, or any other 

taxon. You will work with a basic taxonomic key as part of today’s lab. 

Phylogenetic analysis of a species involves a number of important concepts: 

Homologies are anatomical features or characters, of different organisms, that have a similar 

appearance or function because they were inherited from a common ancestor that also had 

them. A character is any feature that the taxonomist uses to study variation within and 

among species. For instance, the forelimb of a bear, the wing of a bird, and your arm have the 

same functional types of bones as did our shared ancestor. Therefore, these bones are 

homologous structures. The more homologies two organisms possess, the more likely it is that 

they have a close genetic relationship.



There can also be non-homologous structural similarities between species. In these cases, the 

common ancestor did not have the same anatomical structures as its descendants. Instead, 

the similarities are due to independent development in the now separate evolutionary lines. 

Such misleading similarities are called homoplasies. 

Homoplastic structures can be the result of parallelism, convergence, analogies, or mere 

chance. 

Parallelism, or parallel evolution, is a similar evolutionary development in different species 

lines after divergence from a common ancestor that had the initial anatomical feature that 

led to it. For instance, some South American and African monkeys evolved relatively large 

body sizes independently of each other. Their common ancestor was a much smaller monkey 

but was otherwise reminiscent of the later descendant species. Apparently, nature selected for 

larger monkey bodies on both continents during the last 30 million years. 

Convergence, or convergent evolution, is the development of a similar anatomical feature in 

distinct species lines after divergence from a common ancestor that did not have the initial 

trait that led to it. The common ancestor is more distant in time than is the case with 

parallelism. The similar appearance and predatory behavior of North American wolves and 

Tasmanian wolves is an example. The former is a placental mammal and the latter is an 

Australian pouched marsupial. Their common ancestor lived during the age of the dinosaurs 

more than 100 million years ago and was very different from these descendants today. There 

are, in fact, a number of other Australian marsupials that are striking examples of convergent 

evolution with placental mammal elsewhere. 

Both parallelism and convergence are thought to be due primarily to separate species 

lines experiencing the same kinds of natural selection pressures over long periods of 

time. 

Analogies are anatomical features that have the same form or function in different species that 

have no known common ancestor. For instance, the wings of a bird and a butterfly are 

analogous structures because they are superficially similar in shape and function. Both of 

these very distinct species lines utilize wings to get off of the ground. However, as we will see, 

their wings are quite different. 

Most researchers today make a distinction between derived and primitive traits (characters) 

when they evaluate the importance of homologies for determining placement of organisms 

within the Linnaean classification system. Derived traits are those that have changed from the 

ancestral form and/or function. An example is the foot of a modern horse. Its distant early 

mammal ancestor had five digits. The bones of these digits have been largely fused together in 

horses giving them essentially only one toe with a hoof. In contrast, primates have retained the 

primitive characteristic of having five digits on the ends of their hands and feet. Animals 

sharing homologies that are derived, rather than only ancestral, are more likely to have 

a recent common ancestor. This assumption is the basis of the approach to classifying 

known as cladistics. Cladistics is a method of analyzing the evolutionary relationships 

between groups to construct their family (evolutionary) tree. 

It is also important to realize that most species are physically and genetically diverse. Many are 

far more varied than humans. When you think of an animal, such as a giraffe, and describe it 

in terms of its specific traits (coat color patterns, body shape, etc.), it is natural to generalize 

and to think of all giraffes that way. To do so, however, is to ignore incredible diversity of 

individuals within a population of animals. This variation is a foundation of evolution.



International Code of Zoological Nomenclature (ICZN) 

Without a set of international rules to follow, the results of taxonomy would be confusing at 

best. The rules of zoological nomenclature are contained in a document known as the 

International Code of Zoological Nomenclature (ICZN). The object of the code is to promote 

stability and universality in the scientific names of animals. All names must be unique, 

universal, and show stability. 

Uniqueness 

Every name has to be unique. If several names have been given to the same taxon, priority 

decides which name will be the valid name. 

Universality 

Zoologists have adopted, by international agreement, a single language to be used on a 

worldwide basis. All animals are given a generic and specific name in Latin. These names are 

in italics or are underlined (i.e. Homo sapiens). 

Stability 

The ICZN attempts to prevent the frequent changing of names to provide stability. 

The names of genera are required by the rules of nomenclature to be unique. But such rules 

do not apply to other taxa, even though duplicate names should be avoided. 

A category designates a given rank or level in a hierarchic classification. Such terms as 

species, genus, family, and order designate categories. 

Organisms, in turn, are not classified as individuals, but as groups of organisms. Words like 

"bluebirds" or "thrushes" refer to such groups. Any such group of populations is called a 

taxon if it is considered distinct to be worthy of being formally assigned to a definite category 

in the hierarchic classification. 

Categories, which designate rank in a hierarchy, and taxa (singular = taxon), which 

designates named groupings of organisms, are thus different. Significant controversy usually 

occurs over whether or not a particular group is truly distinct enough to be a new taxon. If it is 

a new taxon, taxonomists then determine which category the taxon will be placed in. 

Much of the task of the taxonomist consists of assigning taxa to the appropriate 

categorical rank. The hierarchy of categories that the classifying taxonomist recognizes is an 

attempt to express similarity (characters shared in common) and recency of common descent. 

The most closely related species (occasionally subject to intense debate) are combined into 

genera, groups of related genera into subfamilies and families, these into orders, classes, and 

phyla. 

Type specimens are selected by the taxonomist to designate individuals which typify the 

described species. Type specimens are placed in museums for study by taxonomists. 

Often the type specimen does not represent all the variation within a species (this is often 

nearly impossible). The type specimen becomes the name bearer of the species. These terms 

relate to type specimens: 

Holotype = the single specimen indicated as "the type" by the original author at time of 

publication of the original description. 

Syntype = one of two or more specimens cited by the author of a species when no holotype was 

designated or it is any one of two or more specimens originally designated as types. 

Isotype = a duplicate specimen of the holotype collected at the same place and time as the 

holotype. 

Neotype = a specimen selected as type subsequent to the original description in cases where 

the original types are known to be destroyed.



Binomial Nomenclature 

A species is a distinctive kind of living thing. There are many definitions of what kind of unit a 

species is (or should be). A common definition is that a species is a group of organisms 

capable of interbreeding and producing fertile offspring, and separated from other such 

groups with which interbreeding does not (normally) happen. Other definitions may focus on 

similarity of DNA or morphology. Some species are further subdivided into subspecies, there is 

no close agreement on the criteria to be used. The species, or scientific, name is a binomial 

- that is, it consists of two parts, a genus name and a species epithet. We call this twoname 

system the Linnaean system of binomial nomenclature. The human species is Homo 

sapiens; Homo ("a man") is the genus and sapiens ("mighty" or "wise") is the species epithet, 

actually an adjective that modifies the genus name. The genus name can be used alone when 

one is referring to a group of species included in that genus, such as Rana (a large genus of 

frogs) or Felis (a genus of cats, including wild and domestic species). The specific epithet, 

however, would be meaningless if used alone because the same epithet may be used in 

combination with different genera. The domestic cat is designated Felis domestica; domestica 

used alone is without significance, since it is a commonly used epithet that identifies no 

particular organism. Therefore, the species epithet must always be preceded by the genus 

name. However, you can abbreviate the genus name when it is used in a context in which it is 

understood. Felis domestica might then be designated F. domestica. 

Scientific names are always Latinized and are recognized internationally. This tends to prevent 

confusion, for although one animal may be called by several different common names in 

different geographical areas, its scientific name is the same the world over. 

The Integrated Taxonomic Information System (ITIS) – www.itis.gov 

The ITIS is the result of a partnership of federal agencies formed to satisfy their mutual needs 

for scientifically credible taxonomic information. Since its inception, ITIS has gained valuable 

new partners and undergone a name change; ITIS now stands for the Integrated Taxonomic 

Information System. The goal is to create an easily accessible database with reliable 

information on species names and their hierarchical classification. The database is reviewed 

periodically to ensure high quality with valid classifications, revisions, and additions of newly 

described species. The ITIS includes documented taxonomic information of flora and fauna 

from both aquatic and terrestrial habitats. Please go to www.itis.gov and peruse the 

website. 

Major Taxonomic Divisions of Life 

Important Formatting Note: 

Be aware that all taxa except the species and subspecies epithets are capitalized; 

species and subspecies epithets begin with lowercase letters. Genus, species, and 

subspecies names are printed in italics or are underlined when written or typed. For a 

complete scientific name of an animal species, both genus and species must be listed. 

Kingdom 

At this level, organisms are distinguished on the basis of cellular organization and methods of 

nutrition. 

Phylum 

Members of a phylum share specific distinctive body plan characteristics that set members of 

that group apart from all other members of the animal kingdom. 

In traditional Linnaean classification, a phylum is subdivided into smaller groups called 

classes; classes are further subdivided into orders; orders into families; families into genera 

(sing. genus); and genera into species (sing. and pl.). In large groups, other categories, such as 

superclass, suborder, infraorder, and subfamily, also exist. 

Class 

The living classes of vertebrates and invertebrates are distinguished mostly on the basis of 

their organ systems, general environmental adaptation, and reproductive strategies.



Important Terms 

classification = The arranging of groups of organisms into sets or divisions on the basis of 

their evolutionary relationships. 

taxonomy = The theory and practice of describing, naming and classifying organisms. 

cladistics = A method of inferring evolutionary ancestry by methodically comparing possible 

evolutionary relationships between organisms and selecting as most likely the relationships 

which require, for instance, the fewest number of evolutionary transformations between 

character states. 

phylogeny = The evolutionary development and history of a species or higher taxonomic 

grouping of organisms. 

Systematic = The branch of biology that deals with the diversity of organisms in relation to 

their classification. Note: in some books, this term is not distinguished from taxonomy. This is 

an umbrella term to describe the processes that describe species. There are three disciplines 

which are united under this broad term. First there is the description of species 

(identification), then there is the naming of names (taxonomy) and then there is the description 

of the relationships among and between taxa (phylogenetics). 

animal = An often mobile (although not always), multicellular eukaryotic heterotroph 

with internal digestion that develops from a blastula. Most animals take food molecules 

into their bodies to be digested by eating other organisms (internal digestion). Animals have 

unique embryonic stages (blastula & gastrula) with distinct layers of cells (ectoderm, 

mesoderm, endoderm). Animals are classified into the Kingdom Animalia. 

invertebrate = An animal that lacks a vertebral column (backbone) and cranium (skull). 

Sponges, cnidarians, flatworms, roundworms, molluscs, annelids, arthropods, echinoderms 

and many other animal types are invertebrates. 

vertebrate = An animal that has a vertebral column (backbone) and cranium (skull). All 

vertebrates are members of the Phylum Chordata. 

Important Animal Development Terms 

gastrula = The embryonic stage resulting from the division of the early cells into three 

major tissue types during early animal development. The gastrula has three tissue layers, 

the ectoderm, mesoderm, and endoderm. The gastrula forms from the blastula. 

gastrulation = The formation of a gastrula. 

ectoderm = The outer layer of three embryonic cell layers in a gastrula; forms the skin of 

the gastrula and gives rise to the epidermis, epidermal glands and nervous system of the adult. 

mesoderm = The middle layer of the three embryonic cell layers in a gastrula; gives rise to 

connective tissues such as bone, blood, the dermis of the skin, muscle and parts of many other 

organs in the adult. 

endoderm = The innermost of three embryonic cell layers in a gastrula; forms the gut of the 

gastrula and gives rise to the innermost linings of the digestive tract, other hollow organs and 

parts of many internal organs.



LAB PROCEDURE 

NAME: 

LAB SCORE: 

Animals are classified into phyla (the taxa groups into which kingdoms are divided) based 

on the basic body plans including the presence of true tissues, type of body symmetry, the 

presence and type of an internal body cavity (coelom), segmentation, and cephalization. 

Displayed about the room are a few representative examples of most of the major animal phyla 

we will study throughout the semester. As you proceed through the lab, answer the questions 

about each group. Utilize your classmates, textbook, the Internet and your instructor to work 

through the answers. You may also find the wallchart at the front of the room to be useful. 

The unknown specimens at the end will require you to use the Key to the Major Animal 

Taxa which will be distributed to you as a separate handout. At this point in the course, you 

may struggle to classify some animals into one of the groups indicated on this key, but by the 

end of the course you should have no difficulty in this task. 

‣ Use the labels next to the specimens to locate each of the following groups in the lab 

and then answer the questions. 

TRUE TISSUES 

A tissue is a collection of cells performing a similar function. 

Generally four basic types of tissues are recognized. 

(with many subtypes as we will see in later labs): 

1. Nervous tissue = uses electrical signals (potentials) to allow communication between cells 

2. Muscular tissue = electrical and contractile allowing for movement of cells/structures 

3. Connective tissue = holds other tissues types together into more complex tissues & organs 

4. Epithelial tissue = lines other tissues types such as the inside and outside of organs 

‣ Circle all of the animals below that possess true tissues. 

Kangaroo Rat Sea Anemone Sponge Dragonflies/Damselflies 

ANIMAL SYMMETRY 

1. RADIAL SYMMETRY 

Animals that can be divided into similar segments by more than two planes passing through 

one main axis (like a pie piece from a pie). 

2. BILATERAL SYMMETRY 

Animals that can be divided along a sagittal (between left and right) plane into two mirrored 

left and right halves. This was a major advancement as animals evolved the ability to do 

directional (forward) movement. There is now a front (anterior) and back (posterior) to the 

animal. 

‣ Write BILATERAL or RADIAL to indicate the symmetry of each of these animals. 

Scorpion 

Butterfly 

Sea Anemone 

Fish 

Sea Star 

Songbird



EMBRYONIC DEVELOPMENT AND BODY CAVITIES 

The bilaterally symmetrical animals are further classified based on whether or not they 

possess a coelom. 

A coelom is an internal body cavity between the gut and the body wall lined with mesoderm. 

As the digestive system (gut) forms in animals with a true coelom, it may develop in one of 

two different ways. This determines if the animal is a protostome or a deuterostome. 

1. ACOELOMATE (ACOELOMIC ANIMAL) 

An animal with no body cavity (coelom) present. 

2. PSEUDOCOELOMATE (PSEUDOCOELOMIC ANIMAL) 

An animal with a “false coelom” or pseudocoel only lined with mesoderm on one side (near 

the ectoderm). 

3. EUCOELOMATE (EUCOELOMIC ANIMAL) or COELOMATE 

An animal with a “true coelom” lined with mesoderm on both sides (near both the 

endoderm and the ectoderm). 

Examine the three worm specimens and using your textbook and the Internet, determine 

which label belongs with each animal and write it on the blank. The determination of 

coelom formation must be made by developmental and internal study of the individual 

animals. You cannot figure out the answer just by looking at the animals – look them up 

in the textbook or on the Internet. 

‣ Indicate the type of coelom present in each worm. 

Nematode worm 

Flatworm 

Earthworm/Annelid 

DEUTEROSTOMES VERSUS PROTOSTOMES 

Bilateral animals diverged early in their evolution into two major and separate lineages; 

Protostomia (protostomes) & Deuterstomia (deuterostomes) 

PROTOSTOMES are a group of phyla in which the mouth forms first and then the anus forms 

as the gut develops. Protostomes are also schizocoelous with spiral cleavage patterns. 

DEUTEROSTOMES are a group of phyla in which the anus forms first and then the mouth 

forms as the gut develops. Deuterostomes are also enterocoelous with radial cleavage patterns. 

Examine the animal specimens and using your textbook and the Internet, determine 

whether each animal is a protostome or deuterostome and write it on the blank. The 

determination of this characteristic must be made by developmental and internal study 

of the individual animals. You cannot figure out the answer just by looking at the 

animals – look them up in the textbook or on the Internet. 

‣ Indicate whether each animal group is a PROTOSTOME or a DEUTEROSTOME. 

Sea Star or Sea Urchin 

Beetle 

Human



METAMERISM (SEGMENTATION) 

Metamerism refers to the serial repetition of similar body segments along the longitudinal 

(long) axis of the body. Each segment is called a metamere or somite. In some animals the 

segmental arrangement includes both internal and external structures. In more evolved forms, 

the segmentation arrangement is not as clear (e.g. humans). Note that the segments do not 

need to look exactly the same as each other in order for an animal to be metameric 

(segmented). 

CEPHALIZATION 

The differentiation of a head with a concentration of nervous and sense organs primarily 

seen in bilaterally symmetrical animals. Cephalization evolved as directional movement 

evolved so animals could more effectively hunt prey and gather food. 

‣ Indicate if each of the following organisms is metameric (M) and/or cephalized (C) by 

placing an M and/or a C on the blank. 

Fish 

Nemertean (ribbonworm) 

Sea Urchin 

Crayfish 

Sea Mouse (polychaete worm) 

Bird 

Ascaris (roundworm) 

SKELETON TYPES 

Animals are further categorized based on the type of skeleton or protective structures they 

possess. Use your textbook and the Internet to help you determine the basic differences in 

these types of skeletons. 

‣ Indicate if each of the following animals has a hydrostatic (write HYDRO), endoskeleton 

(write ENDO), exoskeleton (write EXO) and/or a shell (write SHELL). Note that some 

may have more than one skeleton type such as a shell and an endoskeleton. 

Indicate all skeleton types that apply to the animal. 

Polychaete worm 

Turtle 

Sea Slug 

Abalone 

Sea Urchin 

Clam 

Cockroach/Insect 

Snake 

Peanut worm 

Desert Tortoise 

Falconiform bird 

Lobster



APPENDAGE TYPES 

Animals can also be classified based on the type of appendages they possess that are used for 

locomotion or feeding. Use your textbook and the Internet to help you determine the 

basic differences in these types of appendages. 

‣ Indicate if each of the following animals has jointed legs (write JL), swimmerets 

(write S), fins (write F) and/or wings (write W). Note that some animals may have 

more than one type of appendage. Indicate all appendage types seen for each animal. 

Bat 

Shrimp 

Bird 

Fish 

Crab 

Insect 

Use of a Dichotomous Taxonomic Key 

Following is a brief exercise in classification that shows you how to use a taxonomic key 

to "run down" or "key out" the classification of an animal when neither its common nor 

its scientific name is known. 

You will be given a handout that is a simple key to the more common phyla and classes of 

animals and free-living protozoans. The key, for the most part, uses external characters 

that can be visualized without dissection. It is designed for use with adult specimens. Like 

most keys, this key is utilitarian in the sense that the animal groups are not arranged in 

perfect phylogenetic sequence, and the characters used in the key may have no particular 

phylogenetic significance for the taxon. They are simply the characters that typically 

provide the best assurance of correct identification. 

A two-choice system serves as the basis of a dichotomous key. In the dichotomous key, two 

contrasting alternatives are offered at once, so you can choose the one that fits your specimen. 

At the end of the choice, you will find a reference number to the next set of alternatives to be 

considered. Again make a decision and proceed in the same manner until you arrive at the 

scientific name of the animal or the taxon to which it belongs. 

This key also has the capacity for reverse use so that you can retrace your steps if you make a 

mistake. In each couplet, the number in parentheses refers to the number of the couplet from 

which that couplet was reached. 

Keep in mind that individual variations exist; keys are based on the average, or "typical," adult 

specimen, whereas your specimen may be immature or somewhat abnormal. It is often very 

helpful to examine more than one specimen of a species or group, if available, when a 

particular descriptive character proves troublesome.



CLASSIFICATION PRACTICE 

Utilize the key to classify the following animals: 

Indicate phylum and if possible class 

Butterfly 

Earthworm 

Frog 

Jellyfish 

Sea Star 

Clam 

Crab 

Sheep Liver Fluke 

UNKNOWN ANIMAL SPECIMENS 

As time permits, utilize the key to classify the following unknown specimens: 

Indicate phylum and if possible class 

1. 

2. 

3. 

4. 

5. 

6. 

7. 

8. 

9. 

10. 

11. 

12. 

13. 

14. 

15.



LABORATORY NOTES:



LABORATORY NOTES: 

Ape Skeletons – Can you name the primate based on their skeleton only? 

Which skeleton is from a gorilla, gibbon, chimpanzee, human, or orangutan?

Zoological Systematics & Taxonomy - Biosciweb.net

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