Marine Science – FINAL EXAM
A Comparative Investigation of Marine Fish Classes
OVERVIEW
In your previous investigation you compared the
anatomy, physiology, biology, ecology, and
biogeography of invertebrate phyla represented in
the world’s oceans. In this investigation you will
turn your attention to marine fish and compare and
contrast two representative members – a shark and a
bony fish -- of this ancient, pervasive, and
economically important group of marine organisms.
A little over 500 million year ago, a group of organisms classified as chordates emerged. These animals,
represented by modern day sea squirts and their planktonic relatives the salps, resemble a cross between
a jellyfish and a sponge at first glance. A closer scrutiny reveals that these animals developed some
anatomical innovations that even humans share. As a result these animals are classified along with fish,
amphibians, reptiles, birds, and mammals in the phylum Chordata. The following three characteristics
are shared by all chordates.
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All chordates possess a single, hollow nerve cord that runs dorsally on their bodies. This cord
differentiates into a brain and spinal cord in higher chordates.
They have a notochord, a flexible rod that lies dorsal to (above) the gut, but ventral to (below) the
nerve cord. This notochord is replaced by vertebrae in higher chordates, but is retained in sea
squirts, salps, and lancelets.
All have pharyngeal (fah-‘rin-jē-uhl) slits. These slits are located behind the mouth but anterior
(in front of) the esophagus in all chordates. In lower chordates, they are used to filter food. In
some organisms they become gills (i.e. fish). In other vertebrates they develop into portions of the
ear, lower jaw, tongue, larynx, trachea, and other important glands and tissues.
In addition, most chordates also share bilateral symmetry, a ventral heart, a complete digestive system, a
well developed coelom with three distinct tissue layers, and a post-anal tail.
Fish were the first vertebrate members of the Chordates. Members of the subphylum Vertebrata are
distinguished from more primitive chordates because they have a backbone which is a hollow formation
of the skeletal system that encloses the nerve cord. In this investigation you will explore two members of
this subphylum to compare how they have changed over time.
In this investigation you will dissect a dogfish and a bony fish.
Spiny dogfish are a type of shark, a cartilaginous fish in the Class Chondrichthyes, a classification they
share with rays, skates, and ratfishes. These fish share a skeleton made of cartilage, ventral copulatory
organs called claspers, and small placoid scales that resemble teeth. In addition, most members have a
heterocoercal tail which means the top lobe is longer than the bottom lobe.
The Class Osteichthyes, the bony fishes, is the largest and most evolutionarily developed group of fishes.
The 23,000 members of this class comprise 96% of all fishes and almost half of all known vertebrates.
They have a bony skeleton, larger cycloid or ctenoid scales, an operculum or gill cover, and usually
possess a homocoercal tail (upper and lower lobes are the same size). Their fins are supported by rays
and spines. Finally, most bony fish also have a swim bladder, a specialized gas-filled sac above the
digestive tract that is used to regulate buoyancy.
In the days to come, you will investigate each of these two taxonomic groups. Through dissection you
will collect information about the overall anatomy and morphology of these two representative fishes.
You will support this information with research. By combining what you learn in the dissection with
what you discover during your research, you will write a comparative paper that compares how each
different group of fish has adapted in its own way to life in the oceans.
Part One - DISSECTION
Students will be divided into five groups for this activity. No more than FOUR students will be permitted
in a group. Listed below are the areas that you will be observing.
External Anatomy, Skeletal & Muscular Systems
 Body shape, coloration, fins, scales, skeleton, musculature
 How are fish bodies structured and protected?
Nervous System & Sensing
 Brain, central nervous system, five senses, lateral line, electroreception
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How do fish sense their environment and respond to it?
Feeding & Digestion
 Mouth, gill rakers, gill arches, digestive tract
 How do fish find, capture, and digest food?
Circulation, Respiration & Regulation of the Internal Environment
 Gills, spiracles, gill filaments, heart
 Osmoregulation
 How do fish maintain a stable internal environment and circulate nutrients and gases?
Reproduction
 reproductive anatomy, sexual life history, fertilization, spawning, embryonic development
 How do fish reproduce?
During the dissections each student should:
- Take digital pictures of external and internal anatomy features to include in report.
- Take notes on the external and internal features of the specimens.
Part Two – RESEARCH
The following information should be investigated and included in your comparative report:
- What are the major tissues/organs that comprise each system?
- With respect to each system, how are all members of each fish class the same anatomically?
How is each class different from the others anatomically?
- How does each class of fishes behave, interact with its environment, or survive based upon
the anatomy of each system.
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(i.e. sharks have no swim bladder so they must keep swimming upward, otherwise they
will sink to the bottom. Also salmon change color and body structure as they travel
upstream to spawn, presumably because hormonal changes and energy demands require
it!)
A few significant sources of information that will help you in this research but to which you are certainly
not limited:
- Castro and Huber – Chapter 8: Marine Fishes as well as other selections from your textbook.
- The Tree of Life Web Project – www.tolweb.org
- Fishbase.org
In addition, laboratory manuals for the perch and shark will be placed at each lab station to assist you
with dissections and research specific to each fish.
Schedule:
Introduction:
Dissection:
In Class Research Days:
Final Report Due
Tuesday May 6th
May 7, and 13 - 14
May 15-16
Wednesday, May 21st, Noon (12pm)
FINAL COMPARATIVE REPORT
Each student should submit a comparative report that meets the following criteria.
- The report will use personal observations and research to describe 5 similarities or
differences in external anatomy. (ex. Scales, fin placement/function, caudal (tail) fin shape
and function, gill covering, mouth shape/placement, reproductive anatomy, eyes)
- The report will use personal observations and research to describe 5 similarities or
differences in internal anatomy. (ex. Liver, reproductive organs, swim bladder, sensory
organs (olfactory bulb, lateral line, hearing), skeleton, gills, swim bladder, digestive system
(stomach and intestines), circulatory system (heart and blood vessels), brain, mouth
(teeth/tongue))
- Digital images, taken by you, that are labeled with the tissues/organs you are comparing or
contrasting.
- Content that explains how each anatomy part has developed from the most primitive fish
(Agnathans) to the more advanced fishes and possibly where this advancement first
developed (ex. Coelom first developed in the worm phylum).
- Content that explains how the various anatomical adaptations of each fish class enable them
to survive in their respective environments.
- Appendix Page where photographs and other possible images you would like to include to
enhance your comparison are placed not included in the 5 page minimum.
- Work Cited Page – provide all print, image, or electronic references used in MLA format***
SUBMISSION
Each student should submit a final report no later than Wednesday, May 21st, Noon (12 pm). This should
be submitted by e-mail to tbiebesheimer@loyolablakefield.org (or students may turn in a hard copy of the
report)
EVALUATION
This report will be worth 100 points. Each report will be evaluated using the attached scoring key.
REFERENCES
Castro, P. and Huber, M.E. 2005. Marine Biology, 5th Ed. McGraw Hill Higher Education, Boston, MA.
Janvier, Philippe. 1997. Craniata. Animals with skulls. Version 01 January 1997 (under construction).
http://tolweb.org/Craniata/14826/1997.01.01 in The Tree of Life Web Project, http://tolweb.org/
Lundberg, John G. 1995. Chordata. Version 01 January 1995 (under construction).
http://tolweb.org/Chordata/2499/1995.01.01 in The Tree of Life Web Project, http://tolweb.org/
Myers, P. 2001. "Chordata" (On-line), Animal Diversity Web. Accessed May 06, 2007 at
http://animaldiversity.ummz.umich.edu/site/accounts/information/Chordata.html.
Marine Science – FINAL EXAM SCORING KEY
A Comparative Investigation of Marine Fish Classes
Student Name: _______________________________________
Grade: ______________ / 100
Punctuality _______ / 10
 Report is submitted on time (10 pts.)

Report is submitted late (5 pts. deducted for each day late).
Research & Content ________ / 60
 Major tissues, organs, and anatomical structures are properly defined in the student’s report.
With no errors (10 pts.)
With few errors (8 pts.)
With numerous errors (6 pts.)
 Student uses personal observations and research to compare/contrast each fish class’ external anatomy.
Effectively (10 pts.)
Somewhat effectively (8 pts.)
Ineffectively (6 pts.)

Student uses personal observations and research to compare/contrast each fish class’ internal anatomy.
Effectively (10 pts.)
Somewhat effectively (8 pts.)
Ineffectively (6 pts.)

Student uses research to describe how fish behave, interact with their environment, and survive based
upon their anatomy. Student uses research to explain the evolutionary advances present in each class of
fish.
Effectively (10 pts.)
Somewhat effectively (8 pts.)
Ineffectively (6 pts.)
Student uses his own digital photographs taken during his dissections to show the major tissues, organs,
and anatomical structures relevant to each anatomical feature he is comparing or contrasting. (10 pts.)
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
Major tissues, organs, and anatomical structures are properly labeled in the student’s digital
photographs.
With no errors (10 pts.)
With few errors (8 pts.)
With numerous errors (6 pts.)
Mechanics/Creativity _______ / 20
 Student thoroughly research and present information relating the two fish classes.
Effectively (5 pts.)
Somewhat effectively (3 pts.)
Ineffectively (1 pts.)
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
Student uses drawing, images, graphics, and diagrams to compare the two fish classes.
Effectively (5 pts.)
Somewhat effectively (3 pts.)
Ineffectively (1 pts.)
Report meets the minimum page requirement of 5 pages (pictures are located on separate appendix page
in addition to the 5 written pages.)
o

Report is shorter than minimum page number. ( 1 point deducted for each page less)
Report contains no errors in capitalization, grammar, spelling, or punctuation (5 pts)
o
Report contains errors in mechanics. (1 pts. deducted for each error).
Citation and Resources ______ / 10
 Student correctly cites all photographic, text, and electronic sources in MLA format. (10 pts.)

Student makes errors in citing photographs, text, or electronic sources in MLA format. (2 pts. deducted
for each error.)