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

Class characteristics:

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.

Amphibian Orders:

Apoda (Gymnophiona)

Caecilians - legless amphibians (not found in the U.S.)

Anura - "without a tail"

Frogs - smooth, moist skin and long hind legs
Toads - bumpy, dry skin and short hind legs

Urodela - "visible tail"

Salamanders - elongated bodies with short legs and a smooth, moist skin. The tail is somewhat thick and flattened side to side to aid swimming.

Nictitating membrane - a clear membrane that protects the eye.
Tympanic membrane - circular "eardrum" behind each eye.
Eustachian tube - connects the middle ear with the mouth cavity.
Mucus glands - lubricates the skin to keep it moist in the air.
Granular glands - secrete substances on the skin for protection.
Vomerine teeth - two rough pads in the roof of the mouth.
Cloaca - a cavity which collects deposits from intestine, urinary bladder, and sex organs.
Glottis - a slit-like opening from the throat to the lungs.

Veterinarian

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 "food tube" of the frog is quite similar to humans containing these structures.

Esophagus Stomach Small intestine Large intestine

The frog brain:

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

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:

• Search - The Animal Diversity Web
• Search - BIODIDAC, digital biology resources
• Species Identification - Audubon Field Guides Online
• The Oklahoma Herpetology Page - by Paul Shipman
• The Case of the Disappearing Frogs - Oregon Coast Aquarium
• Declining Amphibian Task Force - The Open University
• Amphibian Malformations - Northern Prairie Wildlife Research Center
• Amphibian Information - North American Amphibian Monitoring Program
• All About Frogs - The Exploratorium
• Frog & Toad Pictures - Mike's Herpetocultural Homepage
• Green Tree Frog - Illinois Natural History Survey
• Newt & Salamander Pictures - Mike's Herpetocultural Homepage
• Missouri's Toads and Frogs - Missouri Conservation Commission
• Frogs and Toads - Cleveland Museum of Natural History
• Identification Keys - Cortland University Herpetology Connection
• Lots of Herp Information - kingsnake.com
• Amphibian Links - Good information from HerpMed
• Herpetology People - Society for the Study of Amphibiams and Reptiles

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