Week 27 Dissection

Frog Dissections

• ​Frogs belongs to the class amphibia which literally means "two lives" – frogs can live on land and in the water

• ​Related to salamanders, toads, and caecilians

• Frogs are cold blooded — This means their body temperatures change to match the temperatures of their environment.

• Most of a frog's lifecycle ​happens in the water

  • female frog lays eggs in the water

  • eggs divide and form an embryo

  • frog hatches into a tadpole that will develop into an adult frog.

​Meet the Frog

• ​Specialized body parts for different functions

• Webbed feet for swimming

• Suction cups on toes for climbing trees

• Bulging eyes, situated on the top and sides of the head, allow frogs to see almost 360 degrees

• Nostrils ​located on top of the head to allow breathing while submerged

• Internal ears located behind eyes

• Long, sticky tongues for catching prey

​Frog Observations: External Anatomy

• ​Moist skin that can change color for camouflage

• Some frogs have serous (poison) glands on their skin​

• Frogs can breathe through their skin or through their mouth

  • In water – water passes through​ skin and oxygen is taken up by capillaries

  • On land – take in air through throat into saclike lungs

• Frog hearts have 3 chambers – ​2 atria, 1 ventricle

  • Why?

    • Frogs have a lower metabolism, so they don't need as much oxygen per liter ​of blood

What will you be identifying?

• Heart

• ​Liver

• Gall bladder​

• Lungs

• Stomach

• Small intestine

• Pancreas

• Large Intestine

​Frog Observations: Internal Anatomy

• Spleen

• Ovaries

• Oviducts

• Kidneys

• Testes

• Fat Bodies

• Mesentry​

1. ​Lay the f​rog on its back and pin its limbs to the tray.

2. Make small incisions with a scalpel.

3. Separate skin and pin to tray

4. Next, make the same incisions, but this time cut the muscle​

5. Look into the body cavity ...

   1. Remove fatty bodies if they obstruct your view inside.

   2. A female frog may have eggs, so you'll have to remove these too.​

​Frog Dissections: Steps

Open Ended

Why are frogs cold blooded?

Open Ended

What might you have to remove in order to get a better look at the frog's body cavity?

Multiple Choice

What tool will you to make incisions in the frog's skin and muscles?

• Shovel

• Hose

• Scalpel

• Pencil

Multiple Choice

How many chambers does a frog's heart have?

• 4 (2 atria, 2 ventricles)

• 3 (2 atria, 1 ventricle)

• 3 (2 ventricles, 1 atrium)

• 2 (2 atria)