Activity Title: Shark Dissection
Subject (Focus/Topic): Observation of Shark Internal and External Morphology
Grade Level: 9th Grade
Average Learning Time: 2 class periods, 180 min
Lesson Summary (Overview/Purpose): Dissect a shark to observe the unique external structure as well
as digestive anatomy and reproductive anatomy
Overall Concept (Big Idea/Essential Question): There are various reasons why we are dissecting a shark.
Sharks are model vertebrates in a sense. We can learn a lot, even about human anatomy, by dissecting a
shark; many of the same systems are present, and it's very easy to dissect a shark and see a lot of the
organs displayed. The reason why we are dissecting this shark is that we want to learn about its
digestive anatomy and reproductive anatomy. This shark's digestive system is very specialized, and so is
its reproductive system.
Specific Concepts (Key Concepts):
 Identify the key external structures of sharks
 Understand the function of the unique external structures of sharks
 Observe the unique length of the shark’s digestive system.
 Understand the importance of the size of a sharks liver
 Observe and understand the shark’s reproductive system.
Focus Questions (Specific Questions:
 What are the external structure of sharks and what is the function
 What is unique about the digestive system of sharks
 Why do sharks have such large livers
 How can one distinguish between a male and female shark
Objectives/Learning Goals:
 Students will be able to identify and explain the function of the key external structures
of a shark
 Students will be able to describe the difference between a human and a shark digestive
system
 Students will be able to explain how to sex a shark
 Students will be able to explain the importance of the sharks liver to its buoyancy
Background Information: Students will visit the following site to familiarize themselves will shark
morphology.
http://jb004.k12.sd.us/MY%20WEBSITE%20INFO/BIOLOGY%202/ANIMAL%20KINGDOM/SHARK%20DISS
ECTION/SHARK%20DISSECTION%20HOMEPAGE.htm
They also need a brief overview of the length of the human digestive system for comparison.
Common Misconceptions/Preconceptions: Students are usually very leary of the skin texture of a shark.
Materials:



Dogfish specimen
Dissecting tray
Dissecting equipment
Technical Requirements: None
Teacher Preparation: Teacher will need to familiarize themselves with the digestive system of the shark
Keywords:
 dermal denticles
 demersal
 claspers
 ampullae of Lorenzini
Lesson Procedure:
Part 1: External Features of interest:
Please locate these structures on your specimen,
1. Two pectoral fins- which provide some kind of lift when the shark is moving.
2. Two pelvic fins in the back
3. A caudal fin
4. And it has two dorsal fins on top.
5. All sharks of this family have one fin spine preceding each dorsal fin.
6. As with many demersal, or deep-water, sharks the common dogfish has relatively large eyes and
large spiracles (holes behind the eyes).
7. The skin of sharks is covered with numerous small dermal denticles or placoid scales.
They cover the shark completely from head to caudal fin, also on the ventral side of the shark,
and they're very important because they give the shark greater hydrodynamic capacity. The
dermal denticles are slightly pointed backwards, and you can feel that by stroking the shark in
one direction, it's relatively smooth, but it's not as smooth in the other
What is the length of your dogfish?
__________________centimeters
_______________ inches
Does your dogfish have claspers? What is the sex of your dogfish?
*Once you have completed part 1 I will sign here for you before going on to part 2.
______________________________ Teacher signature
Part 2: Initial Dissection
You will be making a very long incision, on the belly of the shark, to expose both cavities of the shark.
The whole cavity here is the coelomic cavity, which is divided into the pericardial cavity, for the heart,
and the pleuro-peritoneal cavity for the digestive, reproductive, excretory organs.
Do not to cut too deep because you don't want to cut any organ underneath
1. Your first cut will be a transverse cut just above the pelvic girdle. We can feel the pelvic girdle,
which is a bar of cartilage that unites both pelvic fins, with your finger. We want to cut above
the pelvic girdle. Use the scalpel to make an incision. After you make an initial incision, use the
scissors. Cut with the scissors pointed upwards. Make
these cuts as deep as possible on both sides.
2.
Make another transverse cut below the pectoral girdle which unites both pectoral fins. You can
also feel that with our finger; it's a hard bar of cartilage.
3.
With your scissors connect these two cuts through the middle of the belly. Do not cut any
underlying organs.
4.
Pull open both flaps of skin to reveal the internal cavities of the shark. Now anchor the skin flaps
on the side of the shark to your dissecting tray using t-pins.
*Once you have completed part 2 I will sign here for you before going on to part 3.
______________________________ Teacher signature
Part 3: Alimentary Tract (digestive)
You may not need to make any cuts for this section.
Digestion: Food moves from the mouth to the (1)orobranchial chamber, the pharynx [or throat] of the
shark, where it is further pushed down into the (2)esophagus. From the esophagus it makes its way into
the (3)stomach. The esophagus and the stomach cannot be differentiated externally; it’s one long tube.
From the stomach, food goes into the (4)intestine, which is very short. The intestine is very important
because that's where absorption of nutrients occurs. The (5)pancreas, is rather small, secretes enzymes
into the intestine for digestion. After absorption of nutrients occurs, the food passes into the (6)rectal
chamber where water is further absorbed. Then it makes its way into the (7)cloaca where it is finally
expelled from the organism.
1. Open the mouth of the shark to observe teeth.
2. Locate and identify all the bold organs from above. Write the names below
1._____________________________
2. _____________________________
3._____________________________
4. _____________________________
5._____________________________
6. _____________________________
7. _____________________________
*Once you have completed part 3 I will sign here for you before going on to part 4.
______________________________ Teacher Signature
Part 4: Liver Dissection
1. There are three main lobes to the liver, please locate the following:
The right lobe
The left lobe
Small central lobe.
2. Cut out the liver by cutting away at its corners and cutting through the bile duct.
3. Place the liver in water in a large container of water. What happens?
4. How would salty ocean water affect this?
5. What would happen to your liver in water?
6. *Once you have completed part 4 I will sign here for you before going on to part
______________________________ Teacher Signature
Part 5: Esophagus and Stomach Dissection
You are going to see difference between the esophagus and the stomach. Together they look like one
long tube.
1.
Make a longitudinal incision throughout the length of the esophagus and stomach, and open it
up.
2. Upon exposing the lumen [the cavity of a tubular organ], you can see where the esophagus
stops and the stomach begins.
a. The esophagus has lots of these small projections called papillae, which secrete
mucus, which enables food to pass through to the stomach more effectively.
b. The stomach has long, longitudinal folds inside called rugae.
3. The stomach of the shark has to digest large chunks of food. (sharks do not chew)
*Once you have completed part 5 I will sign here for you before going on to part 6.
______________________________ Teacher Signature
Part 6: Intestine Dissection
1. Locate the relatively short intestine of the shark. Sharks are carnivores; carnivores generally
have shorter intestines than herbivores.
2. Sharks compensate for this apparent problem by having a spiral valve, or a scroll valve, inside
the intestine to increase the absorptive surface of the intestine.
3. Make a longitudinal cut (the length of the intestine), exposing the spiral valve.
4. Distinguish between the spiral valves and food in the intestine.
You have now finished your shark dissection. I will sign here for you before your cleanup.
______________________________ Teacher Signature
Cleanup: (in this order)
1. Dissecting specimen is to be placed in large biohazard container. Only dogfish are to be put in
this container no trash.
2. Clean dissecting equipment, including tray with water.
3. Wipe down all surfaces with disinfectant spray.
4. Put away goggles and aprons
5. Wash hands with soap to kill any bacteria.
Assessment and Evaluation: Teacher will check knowledge through observation and oral questioning
and will sign off at each stage of the lab upon successful completion.
Standards:
National Science Education Standard(s) Addressed:
 Content Standard A- Scientific Inquiry
 Content Standard C- Life Science:
Biological Evolution
Diversity and adaptations of organisms
Ocean Literacy Principles Addressed:
 Ocean Principle 5: The ocean supports a great diversity of life and ecosystems.
c Most of the major groups that exist on Earth are found exclusively in the ocean and the
diversity of major groups of organisms is much greater in the ocean than on land.
State Science Standard(s) Addressed: Next generation Science standards
Life Science
HS-LS2-6. Evaluate the claims, evidence, and reasoning that the complex interactions in
ecosystems maintain relatively consistent numbers and types of organisms in stable conditions,
but changing conditions may result in a new ecosystem.
HS-LS2-8. Evaluate the evidence for the role of group behavior on individual and species’
chances to survive and reproduce.
Additional Resources:
http://jb004.k12.sd.us/MY%20WEBSITE%20INFO/BIOLOGY%202/ANIMAL%20KINGDOM/SHARK%20DISS
ECTION/SHARK%20DISSECTION%20HOMEPAGE.htm
Author: Christopher Sanborn, Plymouth Regional High School. csanborn@pemibaker.org
Creation date: 8/4/15