Dissecting our Specimens
Materials:
When performing a dissection, the following materials were used:
Dorsal (back)
Ventral (front)
Posterior (top)
Anterior (bottom)
When performing a dissection, the following materials were used:
- Labcoat
- Scalpel
- Dissecting tray
- Scissors
- Forceps
- Probe
- Hand lens
- Gloves
- Goggles
Dorsal (back)
Ventral (front)
Posterior (top)
Anterior (bottom)
Reptile - Snake
The snake's skin is made up of mostly scales. Scales are made a of protein called keratin which are cool and dry and help retain moisture within the body. Some back (dorsal) scales promote camouflage.
Examining from the tail, we noted that there is an opening called the cloaca, which secretes waste and a mating site (where female eggs are released).
Examining the snake from the ventral side near its belly, we noted that the scales are assist in movement.
At posterior end, the eyes are located at the top to increase the field of vision. The lower jaw is made of 2 separate bones to enable elasticity when eating prey.
After observing the external part of the snake, we made an incision through the skin at the ventral surface and we noted all of the structures inside of the snake. Snakes have a right lung which is the only one lung working. In terms of the heart, the snake has 2 atria and 1 ventricle, mixing oxygenated and deoxygenated blood. The structures associated with the urinary system are the gonads and bladder.
Examining from the tail, we noted that there is an opening called the cloaca, which secretes waste and a mating site (where female eggs are released).
Examining the snake from the ventral side near its belly, we noted that the scales are assist in movement.
At posterior end, the eyes are located at the top to increase the field of vision. The lower jaw is made of 2 separate bones to enable elasticity when eating prey.
After observing the external part of the snake, we made an incision through the skin at the ventral surface and we noted all of the structures inside of the snake. Snakes have a right lung which is the only one lung working. In terms of the heart, the snake has 2 atria and 1 ventricle, mixing oxygenated and deoxygenated blood. The structures associated with the urinary system are the gonads and bladder.
Aves - Pigeon
The pigeon that we dissected displayed the general anatomy of an ave. The forelimbs were modified into limbs. The body is covered in feathers. The general anatomy of a feather has vanes connected to a rachis and this enables the bird to move up and down to promote flight. In order to observe the structure of the pigeon, we made an incision at the tip, however the pigoen has an adaptation called the keel (the sternum) which assists in aviation (R. M. Alexander 1992). The pectoralis (pulling wing down) and the supracoracoideus (pulling wing up) are the structures that assist in flight. The adaptation made with pigeons is that muscle has moved so it inserts the dorsal side of the humorous, giving power in both wings (R.M. Alexander 1992). The three body systems that we observed were: the digestive tract, female and male reproductive systems. The structure of the digestive tract differs due to the introduction of the crop, gizzard and cloaca.
Mammals - Pig
We dissected a relatively small pig, which had limbs that were cloven into 3 separate 'feet' like structures.The pig was covered with 3-4 dermis layers of skin. We started our dissection at the epiglottis, where we observed the internal anatomy. The heart has 4 chambers as every mammal does with the septum separating the oxygenated and deoxygenated blood and the presence of ventricles prevent back flow. The umbilical chord is present in this small pig which distinguishes mammals from other vertebrates - the presence of the placenta during fetal development. Mammals have diverse and specialized teeth, with four main categories such as molars, pre-molars, incisors, and canines. Each are designed to either rip, tear,or crush.
Perch (Fish)
In general, the structures of fish are very different from the other vertebrates. For one, fish are aquatic organisms that have adapted to living in an environment that is denser than air and resists fast motion. Fish have gills that obtain oxygen in its gas form. Thus the heart is two-chambered, having single loop circulation so blood is pumped from the heart to the capillaries. Fish also have a swim bladder which is a flotation device that allows the exchange of gases in the fish. Upon first looking at the fish, the following structures were identified: dorsal gills, pelvic fin, anal fin, caudal fin, lateral line and the anterior posterior fin.
Amphibians - Mud-puppy
Mud-puppies are aquatic salamanders. We noted that the heart was very small, and amphibians typically have 3 chambered hearts, so it is partially divided. They have a cloaca associated with reproduction. They have flat heads, wide tails, stubby legs, and feet with four distinct toes. Their bodies are gray or brownish-gray with blue-black spots. They are also distinguishable by the red external gills.
Works Cited
Alexander, R. M. 1992. Exploring Biomechanics. Scientific American Library, 247 p.
Alexander, R. M. 1992. Exploring Biomechanics. Scientific American Library, 247 p.