Vertebrate Comparisons

Class Mammalia vs. Class Amphibia

Male rat (Mammalia) and male bullfrog (Amphibia).

Mammalia

Thermoregulation - hair, sweat glands.

Mammary glands - produce milk.

Viviparous development - retained within body of female to keep warm.

Nourishment - blood vessels through placenta (allows exchange of nutrients and wastes).

Amphibia

Metamorphosis -  aquatic and terrestrial life.

Lack of amniotic sac - lay eggs in moist environments.

Ectothermic (cold-blooded) - body temperature regulated by external environment.

Fetal Rat Dissection

Class Mammalia

Pregnant Rat Dissection

Mammary glands - produce milk.

Viviparous development - retained within body of female to keep warm.

Nourishment - blood vessels through placenta (allows exchange of nutrients and wastes).

Babies out of the uterus.



Mama rat's eleven babies.



Some info - pregnant, double injected, vacuum packaged -
but  unfortunately not how far along she is!

 Reproduction

 - in the female, the uterus passes to the bladder. Where the horns of the uterus join to the urethra, is the vagina which opens to the exterior through the vaginal opening. On the exterior the anus is anus is ventral to the tail, the vaginal opening is ventral to the anus and the urethral opening is ventral to the vagina. The ovary is found at the anterior end of each uterine horn. The embryos form inside the uterus, along each 'horn'.

- in the male, the testes are located in the scrotum. The epididymis is located around each testis and the vas deferens leads from each testis to the urethra. On either side of the bladder are the prostate glands and seminal vesicles. The urethra goes through the penis, and both the bladder and the testes empty to the outside through the urethra.

Reproductive Organs

Uterus - consists of two tubes (horns), y-shape allows for the growth of multiple embryos.
Ovaries - pea-sized organs.
Oviducts - tightly coilded tubes leading from the ovaries to the horns of the uterus.

Vagina - opens to the exterior through the vaginal opening.

Penis - found in the fur covered prepus (foreskin).
Epididymis - where sperm are stored, highly convoluted tubules.
Vas deferens - carries spern to the urethra.

Testes - where the sperm is produced.

Mama rat's big - she's got babies that were growing inside her.

Many nipples for feeding her many young.

Urethral opening, vaginal opening, anus.

Uterus - each 'bubble' has a fetus inside.

Anterior end of one uterine horn - ovary.

Fetus - out of the embryonic sac.

Nourishment - blood vessels through placenta -
allows exchange of nutrients and wastes.

Horn/y-shaped uterus means room for lots of babies!

A very tiny rat fetus.

Eyes are not developed until after the rat is born.

 

Rat Dissection

Class Mammalia

Thermoregulation - hair, sweat glands.

Mammary glands - produce milk.

Viviparous development - retained within body of female to keep warm.

Nourishment - blood vessels through placenta (allows exchange of nutrients and wastes).

Our male rat - internal anatomy.

Locomotion - tetrapod (four legs), digitigrade (walks on digits only, with the rest of the foot elevated)

Skeletal System - The skull houses the brain, it's strength is necessary to resist the forces produced by the powerful jaw mucles. The vertebral column supports the body and transfers the weight to the appendages. There are five groups of vertebrae (cervical, thoracic, lumbar, sacral and caudal) although no two vertebrae are exactly alike. The sternum and ribs protecta and incase the organs and help in ventilation of the lungs.

Digestive System - Food enters the mouth where the upper and lower incisors can grind down the food. It then goes down through the esophagus into the cardiac portion (entrance from the esophagus) of the stomach, it then makes its way through the fundic and pyloric portions, through the pyloric sphynctor and into the duodenum. The food makes it's way through the small intestine, then the large intestine where water is absorbed and finally into the rectum where the feces is stored before it is eliminated through the anus.

External Anatomy

Vibrissae (whiskers) - integumentary system, used for tactile sensing.
Mouth - digestive system, food enters into the mouth.

External Nare (nostrils) - respiratory sytem, air enters the nostrils.

Pinnae (external ears) - nervous system, used for hearing.

Eardrums - nervous system, protected within the skull, terrestrial environment.

Scales - integumentary system, on tail, protection.

Claws - sharp, grabs onto things (locomotion, diet).

Anus - digestive system, posterior opening of digestive tract.

Penis - reproductvie system, found in the fur covered prepus (foreskin).

Scrotom - endocrine system, contains testes, anterior to the anus, kept cooler than body temperature (located outside the abdominal cavity) to produce viable sperm.
Tongue - digestive system,
Glottis - respiratory sytem, opens to the rachea (leads to the lungs).
Epiglottis - respiratory sytem, protective covering of the glottis, keeps food out of the trachea when the rat swallows.
Incisors - digestive system, gnawing teeth, grow at a fast rate, constantly worn down.

The tail is covered with scales and hairs.

Eardrums protected within skull.

Body covered in hair - protection.

Whiskers - act as the rat's eyes in it's possibly dimly lit home.

Hind feet - sharp claws.

Teeth for gnawin'.

Male posterior end - notice the scrotum.

Female rat posterior end - no scrotum.

Internal Anatomy

Esophagus - digestive system, leads to the stomach.
Stomach - digestive system, seperates from small intestine by the pyloric sphyncter (a muscular valve).
Large intestine - digestive system, ends the muscular rectum.
Liver - lymphatic system, produces bile (rat has no gall bladder).
Pancreas - located in the loop of the small intestine.
Spleen - lymphatic system, located next to the stomach, break down old red blood cells.
Kidneys - urinary system,
Bladder - urinary system,
Testes - endocrine system,
Urethra - urinary system, reproductvie system, where urin leaves the body, as well as carries sperm.
Seminal Vesicles and Prostate - endocrine system, glands that add fluids to the semen before it passes into the urethra.
Diaphragm - respiratory sytem, sheet seperating abdomen from thorax, when it contracts air is sucked into the lungs.
Heart - circulatory system, four chambers: right atrium, left atrium, right ventricle, left ventricle.
Aorta - circulatory system, artery.
Lungs - respiratory sytem,

Under the skin - muscle.

Rib cage - under the muscle - protects organs.

Three lobes of the liver - below the ribcage.

Intestines - below the liver.

One lung.

The heart.

Stomach - right under the liver.

Stomach of the rat.

Insides of the rat's stomach - rats are omnivores.

Small intestine. 

Small intestine.

Intestines unattached.

Inside the large intestine.

Rectum

Inside the rectum - waste.

Inside the scrotum - a testicle.

Seminal vesicle - vas deferens. 

Here is what's inside the testes.

Lungs, heart, diaphram, liver, intestines...

Bullfrog Dissection

Class Amphibia

Group Anuran

No tail, skeleton adapted for jumping.



Ms. Spencer Jr's open for learning.

 Tetrapod

External Anatomy

Limbs
Digits - forelimbs have four digtis (fingers); hind limbs have five. The hind feet are webbed as an adaptation to swimming.
Amplexus - technical term for when frogs mate, the male grasps the female's trunk with his forelimbs.
Skin - used for repiration when warm and active, secretes a protective mucas which minimizes water loss.
Cloaca - located in the posterior abdomen, where the digestive/urogenital systems open.
Eyes - large, adapted to spot insects (diet).
Nictating Membrane - transparent eyelid which cleans/protects without blocking vision.
Tympanic Membrane - external eardrum, derived from lateral line organ, adapted to hear in aquatic and terrestrial environments.
Tongue - sticky, attatched to front of mouth (unlike humans), traps insects (diet).
External Nare - nostrils, connects to oral cavity.
Vomerine Teeth - located in roof of mouth, hold on to prey.
Glottis - located on floor of pharynx, opening to the respiratory system.
Eustaenian Tubes - connect to middle ear.

Inside the mouth - right in the center you can see the glottis.

Our massive she-bullfrog's underside!

Four digits on the forelimbs.

Hind feet are webbed - adaptation for swimming.

Eye and tympanic membrane - adaptation to aquatic/terrestrial environment.

Sticky tongue attached at the front (diet of insects).

Internal Anatomy

Liver - large, has three lobes
Gall Bladder - stores bile (made in the liver, breaks down fat) and passes it to the duodenum.
Esophagus - leads to the stomach, digestive system.
Stomach - pyloric valve separates from small intestine.
Small Intestine - relatively short because frog is carnivorous.
Rectum - opens into the cloaca.
Fat Bodies - yellow finger-like projections, store fat, floatation, warmth, energy.
Kidney - form concentrated urin.
Bladder - thin tranluscent sac, water actively reabsorbed from urine by the bladder.
Ovaries - located at anterior end of the kidneys, attatched to the body wall.

Under the layer of skin you can see the muscle.

The red shows oxygenated vessels - the inside of the skin.

Blue - unoxygenated.

Once the layer of muscle is removed...

Yellow finger-like fat bodies - floatation, warmth.

Where the eggs are - the ovaries.

 

Fat bodies - resemble tentacles...



Three lobes of the liver.

Liver in place - right, left anterior, left posterior.

The heart.

Small intestine.

Lungs - bullfrogs also breathe through their skin.

Stomach - pylorus - small intestine.

Guess what this is!

Very muscular thigh - hops, swims, propels!

A final look, thank-you Ms. Spencer Jr!