Fetal Rat Dissection

Reproductive System

• Uterus (uterine horns)- where the babies develop
• Ovaries- produce eggs
• Nipples- nourish young after birth
• Oviducts- connect the ovaries to the uterus
• Placenta- fetal and maternal circulations to exchange nutrients and wastes during development



The Uterus in the rat is Y-shaped so that it can produce
 multiple babies at one time compared to the
humans uterus which is pear shaped



Rat Dissection






The internal anatomy of the rat looked very similar to that of the frog.

The Digestive System

• Mouth
• Epiglottis- keeps the food from going down the trachea
• Esophagus
• Stomach- stores and physically breaks down food, digests protein
• Small Intestine- 3 regions = Duodenum, Jejunum, Ileum 
• Large Intestine (colon)- 3 regions = Ascending, Transverse, and Descending
• Caecum- pouch that separates the small and large intestine (similar to the appendix in humans)
• Rectum- stores feces until they are expelled from the anus

The Urogenital System

• Prepuce- foreskin
• Penis
• Prostate gland and seminal vesicles- secrete materials that form semen 
• Scrotum sac- contains the testes
• Testis- produce sperm and male hormones
• Vas Deferens- moves sperm from the epidymis to the urethra
• Epididymis- collects and stores sperm cells

• Kidneys- Regulate electrolytes and blood pressure, naturally filter blood, produce urine (excrete wastes such as urea and ammonium in the urine) and reabsorb water, glucose adn amino acids.
• Bladder- store and release urine.
• Ureters- connect the kidneys with the bladder



The lungs in the rat were smooth while
 the lungs in the frog were bumpy and the
gills in the fish were feathery

The Respiratory System

• Nose
• Glottis- leads to the trachea
• Trachea- the cells in the trachea
• Lungs- where gas exchange occurs



The skin and fur protect the animal and keep it from drying out

 The Integumentary System

• Skin 
• Fur

The Circulatory System

• Heart- brings oxygen-rich blood to living cells.
• Veins- bring blood towards the heart
• Arteries- bring blood away from the heart
• Pulmonary Circuit- transportates blood between the heart and the lungs

http://biology.kenyon.edu/courses/biol09/Rat/circulation/framecirc.htm
http://www.buzzle.com/articles/trachea-function.html
http://www.biologycorner.com/lesson-plans/anatomy/

Frog Dissection

• Class Amphibia
• Tetrapods
• Deuterostomes
• Limbs are attached to side
• Chordates have coelomates and 3 germ layers

Growth Cycle

• Larvae become tadpoles. Tadpoles undergo metamorphis and become adult frogs.

Diet

• Insects

External

• Digits- 4 on the fore limbs, 5 on the hind limbs (these ones are webbed for swimming).
• Eyes- Very large for spotting insects. They can sometimes be higher than the top of the head so that the body of the frog can stay emerged in water and the eyes can stay out of the water.
• Eyelids- One is transparent and comes up from the bottom of the eye (nictitating membrane). Its purpose is to keep the eyes clean when swimming but is transparent so that the frog can see.

  

  The bullfrog has 2 eyelids compared to the fish in our earlier dissection which had none.

• Eardrum- The tympanic membrane can pick up vibrations in the water or air. This can be useful for listening for prey or predators and mating.
• Vomenne teeth- Hold the prey until the frog swallows
 

• Glottis- opening to the lungs. The frog needs it to vocalize and breathe
• Vocal Sacs- Only in males.
• Eustachian tubes- equalize pressure in the inner ear when the frog is swimming
• Two Hings limbs- These are very muscular. They have 5 digits on each limb which are webbed to assist in swimming.

• Two Fore limbs- These have 4 digits on each limb. In male frogs there is a thumb pad that helps the male grasp the female when mating.
• Tongue- attached to the front of the mouth for easier insect catching.

Internal

• Fat Bodies- the frog needs them for mating and hibernation

Digestive System

• Liver (3 large lobes)- make bile that emulsifies fat

• Gall bladder- Stores extra bile
• Esophagus- leads to the stomach
• Stomach- stores food and mixes it with enzymes to begin digestion

• Small Intestine- the main place where digestion and absorbtion of digested food occurs
• Large Intestine- stores undigested food
• Rectum- end of the large intestine
• Cloaca- where the products of the digestive and excretory system meet and then leave through the anus.
• Pancreas- secretes digestive enzymes into the duodenum (part of the small intestine)

Excretory System

• Kidney- filters blood, excretes wastes by making urine
• Adrenal Glands
• Bladder- stores urine until it is released

Reproductive System

• Testes (male)- where sperm is produced 
• Seminal Vesicles (male)- collect sperm before entering the cloaca

• Ovaries (female)- produce eggs
• Oviducts (female)- carry eggs from the ovaries to the cloaca

Respiratory System

• Lungs- the place where gas exchange takes place (oxygen to carbon dioxide)

Circulatory System

• Heart- pumps blood to the body using veins and arteries
• Spleen- makes, stores and destroys blood cells

Nervous System

• Brain- main organ of the nervous system

http://www.masd.k12.pa.us/facility/teachweb/frankTodd/Internet%20Activities/FROG%20PAGE/frog%20definitions%20page.html

http://biologycorner.com/worksheets/bullfrog/index.html
http://www.biologycorner.com/worksheets/frog_external.html

Perch Dissection

External

• Eyes

• Fins- dorsal (stability), pelvic (stability), pectoral (side to side movement), caudal (propels), anal (stability)
• Lateral line

• Operculum and Gills

Internal

• Liver

• Heart (atrium and ventricle)
• Swim bladder- controls buoyancy
• Mouth, Pharynx, Esophagus, Stomach (snails!), Intestine, Anus
• Brain and large Optic nerves

Diet

• Snails

Earthworm Dissection

Worms are in three phyla: Annelida, Nematoda and Platyhelminthes

Earthworms are in one phyla: Annelida





Annelida- coelum

Nematoda- A cavity between the digestive tract and the body wall. It develops from the blastocoel and is called a pseudocoel

Platyhelminthes- bilateral

Clitellum- The clitellum secretes a mucus which helps keep the worms together when exchanging sperm (copulation). The clitellum eventually slides off and is a cocoon for the new worms.

Oviducts- Where the eggs are stored.

Prostomium- It covers the mouth and is used to dig through the soil.

Seminal Receptacles- Sperm that is received is stored here.

Seminal Vesicles- Sperm is made here.

Setae- Small bristles that help the earthworm move by providing traction.

Nephridium- Removes metabolic wastes.

Crop- After food comes through the esophagus it passes through here. Food can be stored here before it passes through the digestive tract.

Gizzard- Food is ground down in here so it can be digested.

Septa- Thread like structures that hold the skin to the organs and separtate the segments.

http://www.angelfire.com/de2/atoy/rep.htm

http://www.britannica.com/EBchecked/topic/121884/clitellum

http://en.wikipedia.org/wiki/Nephridium

http://www.backyardnature.net/earthwrm.htm
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/I/Invertebrates.html#Platyhelminthes

Hydra: Phylum Cnideria



The diagram below will help you locate the bud, basal disc and tentacles on this hydra

  Some information is from the red book (Animals without backbones, pg. 81)

http://en.wikipedia.org/wiki/Hydra_(genus)
http://www.madsci.org/posts/archives/2000-11/973856032.Zo.r.html

Morphology- At one end of a hydra is a adhesive foot which is called the basal disc. At the other end is the mouth and one to twelve tentacles (cnidae). Each tentacle has cnidocytes (stinging cells) which containg nematocysts that shoot out a paralysing dart like thread when a little trigger hair (cnidocil) comes in contact with prey. The hydra has two main body layers (epidermis and gastrodermis) that are separated by a gel-like substance (mesoglea). Respiration and excretion occur by diffusion in the epidermis layer.

Habitat- Unpolluted fresh water lakes, streams and ponds in temperate and rainforest areas.

Movement- The simplest movement is by gliding (ameboid movement by basal cells) yet the fastest method looks somewhat like somersaulting. The tentacles attach to the bottom (adhesive thread capsules), the base is "thrown" over, the base attachs to the bottom again, the tentacles release and this whole procedure is repeated.



A Somersaulting Hydra



On this hydra there are 6 tentactles
that help it eat and move.





Eating- The tentacles stretch out and when one comes in contact with prey it paralyses it. The tentacles wrap around the prey and slowly bring it to the mouth. Digestive enzymes are released to break down the food and then phagocytosis occurs to engulf the bits of food.

Land Lubber Grasshopper Dissection

http://www.google.ca/searchhl=en&pwst=1&rlz=1R2GGIE_en&defl=en&q=define:Cephalization&sa=X&ei=4ZwSTeS_OZC-sQOsqtS6Ag&ved=0CBUQkAE

• Grasshoppers are from the phylum Arthropodia and the class Insecta
• Cephalization - over many generations, the nervous tissue becomes concentrated towards one end of an organism. In this case the nervous tissue of a land lubber grasshopper has cephalized toward the anterier end, making sensory organs (eyes and antennae).
•  Eyes ( http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/C/CompoundEye.html , http://en.wikipedia.org/wiki/Simple_eyes_in_invertebrates )

- Two huge compound eyes that have many ommatidia on them (each one is a visual receptor). Each ommatidium consists of a lens (single facet), a crystalline cone, light-sensitive visual cells (arranged in radial pattern and pigment cells (separate the ommatidium). The compound eye is great at detecting movement. The compound eye can also respond to ultraviolet light (we can't see this light).



A diagram of a compound eye. You can slightly see the
ommatidium on the eye in the picture to the left.





Compound eyes and antenanae
are a result of cephalization







.

- Three small simple eyes (dorsal ocelli) that consist of a cornea (lens) and a layer of photoreceptors (rod cells). The ocelli are far more sensitive to light. The diagram below shows where on a grasshopper head the ocelli are located.

• Mouth ( http://en.wikipedia.org/wiki/Insect_mouthparts )

A Diagram of the Grasshopper Mouthparts

- Mandibles - crush, tear, cut and chew food  

- Maxillae - manipulate food during mastication (chewing)

- Maxillary and Labial Palps - sensory receptors for sensing characteristics of food

- Labium - the floor of the mouth, assists chewing

- Hypopharynx - assists swallowing

- Labrum - upper lip

• Thorax ( http://www.biologyjunction.com/grasshopper_dissection.htm , http://wiki.answers.com/Q/Function_of_spiracles_in_grasshopper )

- Two wings - the outer wings protect the flying wings

The Bottom wing is the protecting wing

- Legs - The first two pairs are for walking and the last pair is for jumping. You can see the different legs in the photo below.

 

A jumping leg from a land lubber grasshopper. This is an example of a jointed appendage.

• Abdomen

- Spiracles - used for respiration. Oxygen comes in and is filtered by tracheae, it is distributed among the cells and then carbon dioxide it taken out.

- Difference between male and female - a female grasshopper has a ovipositor. A comparison is shown in the diagram below.



If you compare this picture with the diagram to the right, you can see that our grashopper is a male.