Fish (Perch) Dissection

Background Information
Where is it found?
The perch is a freshwater fish that is commonly found throughout the British Isles and much of Europe, South Africa, and Asia.
What does it eat?
The perch's diet consists of worms, small fish, and larvae.
How does it breath?
The perch takes in oxygen through its gills which are located on either side of its head. Water enters through its mouth and travels through blood vessels to the gills which filters out carbon dioxide.
Fun fact:
When threatened the perch raises their spiny fins as a defense against being eaten.

Gills- used for breathing 

Swim bladder- contributes to fish's ability to control buoyancy without wasting energy

Liver- acts as a food reserve 

Stomach- digests food

Heart- pumps blood to other parts of body

Use dissecting pins to secure the fish to the dissecting pan. Use scissors to make the cuts through skin and muscle. After making the cuts, carefully lift off the flap of skin and muscle to expose the internal organs in the body cavity.

Grass Frog Dissection

Where is it found?
Grass frogs are found throughout most of North America including Southeastern Virginia, eastern North Carolina, eastern South Carolina, and southern Georgia. The grass frog can be found in meadows, gardens and woodland, and prefer shallow areas of water.
What does it eat?
Frogs tend to prey on insects, worms, snails, and slugs.
How does it breathe?
The grass frog can breathe through its skin.  Because of this, the frog is able to hibernate for months.
Fun fact:
When a male frog successfully attracts a female companion, it will wrap its forelimbs around the female in an embrace.

Liver- secretes bile and processes digested food

Stomach- stores food and begins digestion

Large intestines- stores undigested food

Gallbladder- sac that stores bile made in the liver

Turn the frog on its back and pin down the legs. Cut the hinges of the mouth and open it wide. Use the diagram below to locate and identify the structures inside the mouth. Use a probe to help find each part: the vomerine teeth, the maxillary teeth, theinternal nares, the tongue, the openings to the Eustachian tubes, the esophagus, the pharynx, and the slit-like glottis.

Starfish Dissection

Where is it found?

Starfish are found in saltwater bodies all around the world.
What does it eat?
A starfish's diet usually consists of clams, oysters, sand dollars and mussels.
How does it breathe?
Starfish breathe through their feet since they are made of a thin tissue in which gasses can pass through easily.
Fun fact:
A starfish's mouth is located on the underside of its body while its anus is located on the upper side of its body.

Spines- to provide protection from predators

Ceolomic cavity- holds organs in place

Center dish- center of body containing mouth 

Inside each arm, locate two long digestive glands called the pyloric caeca. These make enzymes to digest food in the stomach. Cut a circular flap of skin from the central disc. (You will have to also cut around the madreporite in order to remove this flap.) Observe the stomach under the central disc. Remove the pyloric caeca from the dissected ray. Find the gonads (testes or ovaries) underneath. These may be small if the starfish is NOT in breeding season. Remove these to see the rest of the water vascular system. Cut off the tip of a ray to observe the parts of the tube feet. Find the zipper-like ridge that extends the length of the ray. The tube feet are attached to these. Locate the bulb-like top of a tube foot called the ampulla. This sac works like the top of an eyedropper to create suction. The bottom of the tube foot is a sucker. Embedded in the soft body wall are skeletal plates called ossicles.

Clam Dissection

'Where is it found?
Clams are found in the coastal saltwater bodies and in shallow freshwater lakes and streams.
What does it eat?
Clams eat plankton.
How does it breathe?
Clam breathe through bivalves that filter their respiration water. Their gills remove oxygen and food particles from the water
Fun fact:
Clams have no eyes, ears, or noses, so they cannot see, hear, or smell.

Gills- used to breathe and move food through body

Foot- can stick out of shell and be used to burrow

Unblock- oldest section of shell

 Mantle- part that forms shell, secretes calcium carbonate 

Cardinal teeth- help shell close properly 

Turn the clam with its dorsal side down and insert a screwdriver between the ventral edges of the valves. Carefully work the tip of the screwdriver between the valves so you do not jab your hand. Turn the screwdriver so that the valves are about a centimeter apart. Leave the tip of the screwdriver between the valves and place the clam in the pan with the left valve up. Locate the adductor muscles. With your blade pointing toward the dorsal edge, slide your scalpel between the upper valve & the top tissue layer. Cut down through the anterior adductor muscle, cutting as close to the shell as possible.

Grasshopper Dissection

"Where is it found?
It is found in grassy areas worldwide.
What does it eat?
Grasshoppers are herbivores that feed on  a variety of plants.
How does it breathe?
Grasshoppers along with other insects use tracheal breathing.
They exchange oxygen and carbon dioxide between their tissues and the air through a system of tubes.
Fun fact:
Grasshoppers have ears on their abdomen.

Hind leg- 

Abdomen- tail area of a grasshopper (contains heart, digestive system, reproductive organs)

Antennae- sense and touch environment

Hind legs- used to jump 

Walking legs- used to walk 

Thorax- mid area, where legs and wings attach

Wings- used for flying

Eye- made up of hexagonal lenses

Using forceps, remove one of the walking legs and identify these parts --- the coxa connects the femur (the thickest part of the leg) to the grasshopper's body; a slender, spiny tibia connects the femur to the tarsal segments (lowest part of the leg). Raise both pairs of wings and locate the first abdominal segment.

Crawfish Dissection

Where is it found?
Crayfish can be found in any body of freshwater including streams, rivers, lakes, and ponds.
What does it eat?
Crayfish eat fish, shrimp, water plants, worms, insects, snails, plankton, and even dead plants and animals.
How does it breathe?
Crayfish breathe through Internal gills.
Fun fact:
Over 350 species of the 500 crayfish species of the world live in the United States.

Gills- used to breathe under water

Dorsal abdominal artery- central artery coming from heart 

Cardiac stomach- receives food from esophagus for storage

Digestive glands- secrete enzymes for digestion of food

Using one hand to hold the crayfish dorsal side up in the dissecting tray, use scissors to carefully cut through the back of the carapace along the dissection line. Cut along the indentations that separate the thoracic portion of the carapace into three regions. Start the cut at the posterior edges of the carapace, and extend it along both sides in the cephalic region.

Worm Dissection

I'm Where is it found?
Worms are commonly found living in soil.
What does it eat?
Worms get their nutrients from things in the soil such as decaying matter and leaves.
How does it breathe?
Worms must stay moist in order to breathe since they absorb oxygen through mucous on their skin.
Fun fact:
Earthworms are both male and female because they produce both egg and sperm.

Anus- excretes waste

Clitellum- excretes sac that holds eggs

Semenal vesicle- hollow organs that hold semen

Pharynx- muscle that sucks in food

Crop- holds food

Gizzard- breaks down the food

Septa- structural segments

Dorsal blood vessel- main blood vessel towards the rear of worms body 

Position your preserved earthworm dorsal side up and pin it down through the first segment and then again further back behind the clitellum.  Cut a slit in the dorsal surface near the posterior pin.  Using fine scissors extend the cut forward to the first segment.  Be careful not to cut too deep.  Starting at the first segment, cut the septa (thin membranes) that internally divide the segments, so the skin can be laid flat.  Use additional pins to hold the integument open and expose the organs.  Continue to lay the skin back until you have uncovered a centimeter or so of the intestine.