Biology Week 21 - Amphibians

Day 1 | Day 2 - 4 | Lab | Weekly Quiz

  • Amphibian
  • Apoda
  • Anura
  • Frog
  • Toad
  • Urodela
  • Salamander
  • Nictitating membrane
  • Tympanic membrane
  • Eustachian tube
  • Mucus glands
  • Granular blands
  • Vomerine teeth
  • Cloaca
  • Glottis
  • Pulmonary respiration
  • Cutaneous respiration
  • Alimentary canal
  • Esophagus
  • Stomach
  • Small intestine
  • Large intestine
  • Pineal body
  • Hibernation
  • Estivation

The Amphibians

click to find the answer to today's question How are hibernation and estivation different?

Class characteristics:link to a local webpage Peeper

Smooth, moist skin (no scales)
Toes lack claws
Gills, lungs, and skin used in respiration
Metamorphosis from larval stage to adult
Larvae heart 2 chambers, adult 3 chambers
Eggs fertilized externally

See where amphibians fit into Earth's history. link to an Internet Website

Amphibian Orders:

Apoda (Gymnophiona) link to an Internet Website

Anura - "without a tail" link to an Internet Website Urodela - "visible tail" link to an Internet Website Specialized amphibian body structures:
click for a career
Two types of respiration:

Pulmonary respiration - exchange of gases between the lungs and the air.
Cutaneous respiration - exchange of gases between the skin and the air/water.

Except for lungs and brain, the relative size and location of a frog's internal organs are similar to humans. This makes the frog a good dissection to begin thinking about human organs.

The alimentary canal:

The frog brain:

frog brain diagram The basic brain functions are as follows:

Olfactory lobe - the center of the sense of smell.
Cerebrum - integrates behavior and learning.
Optic lobe - process information from the eyes.
Cerebellum - the center of muscular coordination.
Medulla oblongata - controls some organ functions, such as heart rate and respiration.
Pineal body - known to regulate sleep patterns in humans, the pineal body is thought to produce the hormones involved in hibernation and estivation in amphibians.

Ten pairs of cranial nerves extending directly from the brain insure that there is continuous communication between most areas of the brain.

Day 1 Assignment - Amphibians
Scoring criteria
link to a local webpage

  1. In what ways are amphibians adapted for aquatic life?
  2. In what ways are amphibians adapted for terrestrial life?
  3. Eustachian tubes are extremely important to frogs. Explain why.
  4. Pulmonary respiration is many times more efficient than cutaneous respiration. Under what conditions do amphibians rely on cutaneous respiration?
  5. There are no amphibians that live in the ocean. Give reasons for this.

Research Links:

Biology Class










Hibernation is a period of inactivity during cold weather and estivation is a period of inactivity during hot or dry weather.