Lab Safety for Dissections
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Safety goggles must be worn at all times because the preservative is
very harmful to your eyes.
If you are injured immediately notify the teacher.
No horseplay or running around the room.
Be careful because scissors are sharp.
Absolutely no body parts leave the room. Dispose of them properly.
Be sure to clean up and wash hands when you are done.
No vomit in Stew’s room!!
Earth Worm Dissection
1.
Insert the point of your scissors about 1 cm posterior to the clitellum
of the worm just to the left of center on the dorsal side. Be sure the
scissors are just under the skin. Carefully cut through the skin to the
mouth.
Using a dissecting needle, sever the muscles between the segments,
opening up the worm. Use pins to attach the skin to the dissecting tray.
Find the organs listed in your notes. Research their functions for your
dissection journal.
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Materials
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Tray
Two paper towels
Gloves
Scissors
Pins
Goggles
Skin
Dorsal Blood Vessel
Seminal Vesicles
Crayfish dissection procedure
1.
Observe the external anatomy of the crayfish. Locate the body
parts that are external. Is your crayfish a male or a female? How
do you know this? Locate the mouth of the crayfish. Observe the
live crayfish in the tank.
Make a cut in the exoskeleton of the cephalothorax on the dorsal
side from the back of the cephalothorax to the rostrum, cutting
down the midline. Separate the 2 halves of the exoskeleton to reveal
the internal organs.
After you find all the internal organs clean up thoroughly!
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Materials
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Tray
Two paper towels
Gloves
Scissors
Probe
Goggles
Pins
Fish dissection procedure
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Identify all the fins of the fish. Find the lateral line, operculum and gills.
Make a cut from the vent on the ventral side of the fish to an area just
below the operculum, cutting between the pelvic fins. Then cut up along
the operculum to the lateral line. Cut parallel to the lateral line until you
are even with the vent, then cut down to the vent and remove the side of
the fish. Locate the internal organs and then clean up thoroughly.
Frog dissection questions
1. How many chambers does a frog heart have? Three chambers
2. How many chambers does a human heart have? Two chambers
3. Which heart is more efficient, and why does it have to be more efficient? A
frog’s heart is more efficient and it has to because in order for it to jump and
catch insects with its tongue.
4. Why does a frog have such small lungs? A frog has such small lungs because
they can absorb oxygen through their skin.
5. How is the tongue of a frog attached in its mouth and why is it attached like
this. The tongue of a frog is attached in its mouth in the front because that way it
can extend out further so it can catch different types of insects at an farther
distance.
6. Why is a frog classified as the following?
a. ectotherm
b. amphibian
c. chordate
d. animal
e. heterotroph
7. Why are amphibian populations declining, and what can we do to save them?
Amphibian populations are declining because of pollution, they effect their eggs
that they produce. What we can do to save them is to stop pollution and stop
litering so it can be a mor3e hrealthier enviroment for the frogs.
8. Explain how a frog is camouflaged. A frog is camouflaged because if it was on
to-p of the water and there was another animal that was looking up to the surface
of the water they would just see yellow which looks like the sun.
9. Is a frog an herbivore, omnivore or carnivore? Explain your answer.
10. Why do scientists dissect organisms? The reason why scientists dissect
organisms is to find out what kind of food they eat and more information about
them that they didn’t know.
Materials
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Tray
Two paper towels
Gloves
Scissors
Probe
Goggles
10 pins
Worm organs
Brain: Is located in the nervous system and is the control center of the body. It is
located under the pharynx.
Aortic arches: It has five of them and is another word for heart.
Crop: It is used to store food.
Gizzard: It is used to grind up organic food and it is the area of the digestive tube
which is quite muscular.
Intestine: It extends, relatively unchanged, from about segment 20 to the
posterior end of the worm.
Dorsal blood vessel: The dorsal blood vessel is used to carry blood from the tail to
the head of the worm.
Seminal vesicles: They are used to store sperm which are produced by the worm.
Seminal receptacles: These are only visible when the worm is in reproductive
condition.
Esophagus: It is a muscular tube that is used to take food and water from the
mouth to the stomach. It serves as a passageway for food.
Mouth: The mouth chews up the food and makes it easier to digest.
Anus: It is used to excrete liquid and solid wastes from the body.
Clitellum: An organ that is responsible for mucus production during reproduction.
Skin: It is used to absorb oxygen.
Fish organs
Operculum: A lid or flaps covering an opening, such as the gill cover in some fish.
Stomach: It is used to store and digest food.
Intestine:
Liver: The liver regulates most chemical levels in the blood and excretes a product
called bile, which helps to break down fats, preparing them for further digestion
and absorption.
Heart: It is responsible for pumping blood through the body.
Swim bladder:
Eye: It is the organ of sight.
Ovaries:
Testes: It is used to produce gametes.
Caudal fin:
Dorsal fin:
Pectoral fin:
Ventral fin: It is used to help it swim.
Pelvic fin:
Lateral line:
Scales:
Frog organs
Skin: It is used for camouflage and protection; outer covering of the frog.
Lungs: It is used to function so it can remove the carbon dioxide from the blood
and provide it with oxygen.
Heart: It is responsible for pumping blood through the body.
Brain: Is located in the nervous system and is the control center of the body.
Ovaries:
Testes: It is used to produce gametes.
Tongue: It is used to catch insects.
Cloaca: a common chamber that receives materials from the digestive, excretory,
and reproductive systems
Spleen: It is used to dispose of red blood cells.
Pancreas: It is a gland that produces both insulin and digestive enzymes; located in
the mesentery inferior to the stomach.
Stomach: It is used to digest food.
Small intestine: It is used to serve to digest and absorb nutrients.
Large intestine: It is used to absorb water from and eliminate the residues of
digestion.
Liver:They are apaired, thin-walled respiratory organs located lateral to the heart.
Gall bladder: It is a small, greenish colored sac that is located under the liver; it
stores bile.
Kidney: It is a paired, dark-brown organ located in the frog's abdominal sidewall
used to filter blood of metabolic wastes.
Bladder: It is used to hold urine.
Fat Bodies: