Fetal Pig Dissection- External Anatomy by u841Zr7


									                                         Invertebrates, The Fetal Pig,
                                       Comparative Vertebrate Dissections


                                     Dissection Partners’ Names:
General Overview: We will spend the rest of the semester on our animal dissections. First, you will dissect the earthworm and
crayfish to allow you to examine two invertebrate species. Then, your lab group of 4 students will spend 4-5 days identifying parts of
the fetal pig and participating in a comparative vertebrate dissection where your group will be the “expert” on one type of vertebrate,
but you’ll also have to learn the other vertebrates from the other groups. You will also be individually completing this lab packet
which includes diagrams and questions. Finally, you will have your lab practical exam on your final exam day. This practical will
count as your Performance Exam for this semester.

Grading: The pig dissection is worth 3 grades:
       *80 total points for 8 days of dissection participation (10 pts per day). This grade will typically be assigned to the entire
       group, but some students may receive different grades because of amount of participation. Your group can earn up to 10
       bonus points for exceptional participation.
       *100 total points for completion of your individual lab packet (10 pts per page).
       *5% of your average for the lab practical test.

Suggested Timeline:
        Fri 5/13- Earthworm Dissection (or if group members are missing because of AP Geography Exam, work on packet and catch up later)
        Mon 5/16- Crayfish Dissection
        Tue 5/17- External structures, Anatomical planes and directions, sexing the pig, skinning the pig
        Wed 5/18- Pig- Muscles, nervous, respiratory, digestive, circulatory
        Thu 5/19- Pig- Urogenital/ excretory, work on packet
        Fri 5/20- Comparative Vertebrate Dissection
        Mon 5/23- Comparative Vertebrate Dissection
        Tue 5/24- Review, Finish
        Wed 5/25-Fri 5/27 (exam periods)- Comparative Lab Practical test, Packets due

     EACH member of the lab group is responsible for learning all of the parts. At least 2 people in each group must be actively
        involved in dissection, but everyone must participate in locating the parts.
     EACH person is required to put in an equal amount of work. You will be graded on your amount of participation.
     EACH person is required to complete an individual lab packet.
     You are expected to be appropriate and a cooperative team member. Additionally, you are expected to treat your specimens,
        materials, classmates, teacher, and work station with respect.

Working Ahead: I strongly suggest that you work ahead since the periods always seem to get shorter as the practical gets closer.
However, please work in order and leave time for review! Listen carefully for options for open lab before or after school.

Daily Cleaning: Clean (with soapy water) and dry dissection tools and tray; Bag and box specimens; Colored Pencils, Dissection
Notebook, Pig Mat, and Soaps where they belong; All trash thrown away (in the garbage can); Sink clean; Tables sprayed and wiped
down; Aprons and goggles returned; Lab stools pushed in
    □ You will lose individual points if you do not help your lab group clean!
    □ You may not leave the classroom until you are checked off!
    □ If your table is left unclean and not checked off after class ends, everyone will lose points!
                                            EARTHWORM ANATOMY
Earthworms (Lumbricus terrestris) are representative animals of phylum Annelida and class Oligochaeta. Examining external and
internal structures of an earthworm will reveal some major annelid characteristics. Lumbricus is an excellent animal for study because
of its body organization. An earthworm is a segmented animal. Its body plan consists of many rings (annelus means “ring” in Latin).
Each segment, or ring, of an earthworm is numbered in sequence from anterior to posterior end. Organs can be located by finding the
particular segments they are known to be in. An earthworm “map” lists the location of each organ or structure by segment number
(see the laminated handout).

Materials –
Preserved earthworm                  straight pins               razor blade               dissecting pan
Dissecting probe                     colored pencils             hand lens

Procedures –
1) Identify the anterior (head), posterior (tail), dorsal (top), and
 ventral (bottom) sides of a preserved earthworm.

A bandlike structure, the clitellum, separates the body into
two unequal lengths. The shorter section (about 1/3 of the total length)
is the anterior portion. The longer section is the posterior portion.
The dorsal surface is darker than the ventral surface and rounded
toward the anterior end. The ventral surface is flat.

2) Stretch your animal out with the dorsal side up in a dissecting pan.

3) Pin the earthworm to the pan with straight pins. Use one pin at each
end of the worm (figure 1).

4) Starting at the posterior end use the razor blade to cut along the
dorsal surface. Caution: Blade is sharp. Cut away from your fingers.
Take care to cut only through the skin and muscle of your worm.
NOTE: An earthworm’s skin and muscle are extremely thin. A very
shallow cut is all that is needed. Do NOT cut the entire length of worm at one time.
 Instead cut 2 – 4 cm sections at a time.

                                              5) Spread the edges apart by carefully cutting through thin membranes
                                               (septa) on the inside of the worm. These septa are continuous with
                                              each groove on the worm’s outside surface.

                                              6) Pin the skin and muscle to the dissection pan as you spread these
                                              tissues apart. Slant the pins out at an angle (Figure 2).

                                              7) Continue to carefully cut and pin your animal until you reach the
                                              anterior end.

                                              8) After you have completely opened your earthworm, identify the
                                              internal organs by using the earthworm “map” and the following
                                              explanations. The organs of each system are listed on the “map” beside
                                              the number of the segment in which they are located. If an organ is in
                                              more than one segment, the segments that it is in are included in
Digestive System
         The digestive system begins with the mouth and is
followed by the pharynx, on which many strands of muscle
fibers may be observed. The esophagus is a thin-walled
tube which continues posteriorly from the pharynx to
segment 13 or 14. The crop and the gizzard are in segments
14 through 20. The walls of the gizzard are muscular for
grinding food. The walls of the crop are thin. The rest of
the digestive system is composed of the intestine which
continues from segment 20 to the anus, the most posterior part.
      in the diagram to the right – label the parts of the
         earthworm’s digestive system
      in figure 3 color all the parts of the digestive system green

                                                                         Circulatory System
                                                                                   The large dorsal blood vessel carries blood from the
                                                                         posterior end of the earthworm to the anterior end. Five aortic
                                                                         arches connect the dorsal and ventral blood vessels. These arches
                                                                         are sometimes called “hearts” because they help pump blood.
                                                                         The “hearts” encircle the esophagus.
                                                                         * in the diagram to the left – label the parts of the earthworm’s
                                                                            circulatory system
                                                                         * in figure 3 color all the parts of the circulatory system red


Reproductive System
         The reproductive system consists of seminal vesicles,
seminal Receptacles, ovaries and testes, and the clitellum. The seminal vesicles are three pairs of saclike structures along the
esophagus. Two very small almost dotlike structures, on each side near the seminal vesicles, are the seminal receptacles.
Ovaries and testes are present in your worm but difficult to observe. They are shown in Figure 3 with dotted lines. The
clitellum produces a mucus slime tube during mating.
         The reproductive system also includes two sets of pores
visible on the exterior of the worm. Segment 14 has a pair of female       testes
pores and segment 15 has a pair of male pores.
      in the diagram to the right – label the parts of the
         earthworm’s reproductive system.
      In figure 3 color all the parts of the reproductive system

Nervous System

                                                                  Nervous System
                                                                            A “brain” (ganglion mass) is a small mass of white
                                                                  tissue in segment 3. It may be destroyed when dissecting a
                                                                  worm. The ventral nerve cord is seen as a white “thread”
                                                                  extending along the worm’s ventral surface from segment 3 to
                                    ganglion                      the last segment.
                                                                  Because of its ventral location, the nerve cord cannot be seen
                                                                  well except where organs have been removed.
                                                                  * In the diagram to the left – label the parts of the earthworm’s
                                                                  nervous system.
                                                                  * In figure 3 color all the parts of the nervous system blue
Excretory System
The excretory system consists of paired organs called nephridia. These are
small organs against the lateral (side) walls of the worm. You may need
a hand lens to see them. They are present in almost every segment.
       In the diagram to the right – label the parts of the         excretory pore               tubule
        earthworm’s excretory system.
       In figure 3 color all the parts of the excretory system

Analysis Questions
1) The skin is the organ of respiration in the earthworm. In order for gas exchange to occur there must be some form
of a liquid for the gases to dissolve in.
a)Explain how respiration takes place through the skin of an earthworm.

b) What happens to the earthworm if its skin dries out?

c) What happens to the earthworm, after a heavy rain, when the soil is flooded?

2) a) To which phylum does the earthworm belong? ________________________

   b) What is the meaning of this phylum name? ___________________________

3) a) What is the scientific name for an earthworm? _________________________________________

   b) To what genus do earthworms belong? __________________________

   c) To what species do earthworms belong? _________________________
                                 CRAYFISH DISSECTION
Part A: Introduction
Crayfish are in Phylum _______________ and Class ___________. They have visible exoskeletons made
of _____________. The crayfish have ____ pairs of __________ appendages that are highly modified for
specific functions. In this lab you will locate the external structures of the crayfish.

Part B: External & Internal Anatomy
Label the external anatomy diagram using these choices: cephalothorax, abdomen, telson, carapace,
compound eye, antennae, uropods, antennules, swimmerets, walking legs, cheliped, tail. Also indicate the
anterior, posterior, dorsal, and ventral sides.

                       rostrum                                   Cephalic groove

Label the internal anatomy diagram using these choices: brain, green gland, intestine, mouth, gills,
duct from testis/ oviduct, anus, esophagus, digestive gland, testis/ ovary, stomach, heart, ventral nerve
cord/ ganglia. Also indicate the anterior, posterior, dorsal, and ventral sides.

Part C: Appendages
   1. Write the function of each appendage on the chart below.
   2. Find each of the appendages on your crayfish, carefully remove them with scissors and tape them down to a
       piece of paper. The appendages should be taped in the order that they appear on the crayfish. Label each
       of the appendages on the paper.
   Body Section                   Appendage                      Function
   Cephalothorax                  Antennules (1 pair)

                                  Antennae (1 pair)

                                  Eyes (1 pair)

                                  Mandibles (1 pair)

                                  Maxillae (2 pairs)

                                  Maxillipeds (3 pairs)

                                  Chelipeds (1 pair)

                                  Walking legs (4 pairs)

   Abdomen                        Swimmerets (5 pairs)

                                  Uropods (2 pairs)

                                  Telson (1)

   Part D: Analysis
   1. Name 3 other Crustaceans that closely resemble the crayfish.

   2. Which pair of appendages are used to obtain and eat food?

   3. Which pairs of appendages are used for swimming?

   4. The exoskeleton of the crayfish does NOT grow with the organism. When they outgrow their exoskeleton
      they undergo a process called ____________________.

   5. Fill in the blanks with the correct answers. Crayfish seize their food with their ____________. The
       ____________ and ___________ crush and chew the food. The ____________ are the excretory organs.
       The ____________ are used for respiration. The brain consists of a pair of ______________. Two large
       nerves extend from the ___________, around the esophagus and join the _____________ nerve cord.
               FETAL PIG DISSECTION- External Anatomy
1.   Receive your pig.
2.   Rinse it under water (no soap!) and dry.
3.   Label your bag with group members’ names.
4.   Label the diagrams and learn the parts on your pig.
5.   At the given time, put your pig in the bag and place your bag in the assigned box.
6.   Clean your supplies and area thoroughly.
7.   Answer the questions.

                                                                       Label anterior, posterior,
                                                                       dorsal, and ventral on the
                                                                       diagram to the left.

Female: Females are identified by the urogenital papilla. This is a small, fleshy, cone-shaped
projection ventral to the anus. Locate the female's external genital opening at the base of the
urogenital papilla. The term urogenital indicates that this is the external opening for both urinary wastes
and reproductive cells.
Male: The male's testes (singular=testis) lie in the scrotum, a pouch ventral to the tail. In older
specimens, this area is enlarged and readily visible. In younger animals, a loose pouch may be visible
but the testes may still be in the abdominal cavity, having not yet descended.

Is your pig male or female? _________________ List at least 2 reasons you

Be able to identify both sexes!
                    FEMALE                               MALE

 Draw lines and label OR
 color code on the diagram to
 the right.
 Hind legs
 Teats/ Mammary papillae
 Umbilical cord

Analysis Questions
   1. Complete the classification of the pig:
      Domain ______________ Kingdom ________________ Phylum ________________

       Class________________ Order __________________ Family _________________

       Genus _______________ Species _________________

   2. Fetal pigs are placental mammals. This means that the baby develops inside its mother, where it is
      connected to her by the placenta, a large organ filled with blood vessels. These blood vessels help
      exchange nutrients, gases, and wastes between the baby and mother. Knowing this, name at least 3
      other animals that would be considered placental mammals.

   3. Using the graph that has been provided, what is the approximate age of your pig?

   4. What are the nares and pinnae more commonly called?

   5. What is the difference between the thorax and trunk?

   6. Define the terms proximal and distal and give an example using both.
     FETAL PIG DISSECTION - Skinning the Pig, Muscles, and Nervous
1. After listening to instructions, carefully skin your pig.
2. Learn the muscles using the diagram provided.
3. Learn the major parts of the sheep brain using the diagrams provided. We won’t be finding these
   structures on the fetal pig since they are so small!
4. Review!
5. Clean your supplies and area thoroughly.
6. Answer the questions.

1.    Place the pig on its back.
2.    Cut a small slit above the umbilical cord (not deep at all!).
3.    Use the probe or your finger to begin to separate the skin away from the muscles underneath. If you
      are seeing organs you are going way too deep!
4.    Cut up to the throat and up one cheek.
5.    Cut down one of the forelegs to the paw. Cut around the paw to leave a glove on the pig.
6.    Continue cutting down to the umbilical cord. Cut around the cord (DO NOT cut the cord off) and
      continue cutting down to the tail area. Continue separating the skin away.
7.    Cut down one leg to the paw. Cut around the paw to leave a boot on the pig.
8.    You will only skin one half of the pig. That means from the middle of the stomach to the middle of
      the back, including one leg, one arm, and one cheek.


       Draw lines and label OR color code the muscles above with the following terms:
       Biceps brachii
       External oblique
       Flexors/ extensors
       Gluteus medius/ maximus
       Internal oblique
       Latissimus dorsi
       Pectoralis major
       Triceps brachii

                                              Draw lines and label OR color code the dorsal
                                              picture of the brain using these terms:
                                              Gyrus ( bump on the surface of the cerebrum)
                                              Media/longitudinal fissure
                                              Spinal cord
                                              Sulcus (groove between the gyri)

                                                     Draw lines and label OR color code the sagittal
                                                     view of the brain using the following terms:
                                                     Arbor vitae of cerebellum
                                                     Corpus callosum
                                                     Spinal cord

Analysis Questions:
1. What do you think the function of the masseter is?

2. What is another name for the tendon of gastrocnemius?

3. What are the 3 types of muscle tissue? For each, tell whether they are involuntary or voluntary and
   where they might be found.

4. For every muscle you learned today, what is the muscle type?

5. Describe the differences in how the gyri and sulci look.
     FETAL PIG DISSECTION - Respiratory, Digestive, Circulatory, Urogenital
  1. After listening to instructions, carefully cut your pig open.
  2. Learn the respiratory, digestive, circulatory, and urogenital systems using the diagrams provided.
     You are responsible for BOTH male and female urogenital systems.
  3. Review! Your test is Friday!
  4. Clean your supplies and area thoroughly.
  5. Answer the questions.

                                                                             Label the diagram of the
                                                                             respiratory system using
                                                                             these terms:

                                                                             Left lung
                                                                             Right lung

                                                                             Remember it’s the pig’s left
                                                                             and right!


                                                          On the diagram of the
                                                          mouth to the left, draw lines
                                                          and label OR color code the
                                                          Hard palate
                                                          Soft palate

                                                  Draw lines and label the
                                                  diagram of the heart using
                                                  these terms:
                                                  Left atrium
                                                  Left ventricle
                                                  Right atrium
                                                  Right ventricle
                                                  Aorta/ aortic arch


On the diagram to the right, label the
internal anatomy of the fetal pig OR
color code using the following terms:
Urinary bladder
Urogenital opening
Gall bladder
Large intestine
Mesentery (net-like tissue over the intestines)
Pericardium (sac around the heart)
Small intestine
                     Draw lines and label OR
                     color code the diagram of
                     the female urogenital
                     system using these terms:
                     Renal artery
                     Urinary bladder
                     Urogenital opening
                     Urogenital sinus
                     Uterus (uterine body)


                    Draw lines and label OR
                    color code the diagram of
                    the male urogenital system
                    using these terms:
                    Renal artery
                    Urinary Bladder
                    Vas deferens
Analysis Questions:

1. Why is the diaphragm important?

2. The rings you see on the trachea are actually made of cartilage. What do you think their function is?

3. What is the function of the ureter and the urinary bladder?

4. Compare the appearance of the hard vs. soft palate.

5. What is the function of the
     a. Epiglottis

       b. Spleen

       c. Liver

       d. Mesentery

6. What type of muscle is found in the esophagus?
                                     COMPARATIVE ANATOMY OF VERTEBRATES DISSECTION
 Locate each of the major structures indicated below. After you do, place a check mark in the blank. Use the “expert” group to help you learn the parts.
Organism       Heart   Liver     Lungs     Small/       Ureter (s)    Cloaca/      Tongue    Teeth    Stomach             Trachea   Gonads/   Additional
                                 / Gills   Large        & Kidney      Urinary/                                                      Male vs   Structures
                                           Intestines                 Urogenital                                                    Female
Pigeon                                                                                                (Crop/ gizzard)                         Feathers, talons,
Snake                                                                                                                                         Esophagus

Salamander                                              XXX                                                               XXX                 Gills

Shark                                                   XXX                                                               XXX                 Fins: dorsal,
                                                                                                                                              pelvic, pectoral,
Perch                                                   XXX                                                               XXX                 Fins: dorsal,
                                                                                                                                              pelvic, pectoral,
                                                                                                                                              caudal, anal
Lamprey                                                 XXX                        XXX                XXX                 XXX                 Mouth, Dorsal
                                                                                                                                              fin and caudal
Frog                                                                                                                                          Tympanic
Additionally, please make sure you can differentiate the dorsal, ventral, anterior, and posterior sections of each organism.

                                                                     Classification Review
                                                    Complete the classification for each of the organisms.

                                 Organism               Domain          Kingdom          Phylum/ Subphylum              Class

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