Frog Communication

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Frog Communication

• Jennifer Calder
• Herpetology
• Winter Term 2003
• Dr. Edwards

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Physiology Communication

• Numerous studies indicate a relationship
  between the morphology/physiology and
  communication of frogs. Frog communication is
  particularly useful for mating, distress, and
  territorial defense.

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Question Answer

• Question 1 Do frogs have ears?
• Answer No
• Question 2 What structures do frogs use for
  listening/hearing?
• Question 3 How do these structures work?
• Question 4 How is the morphology/physiology
  connected to the communication in frogs?

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Question 2

• What structures do frogs use for
  listening/hearing?
• ANSWER
• ear drum (tympanum)
• inner ear
• brain
• middle ear (only some frogs)
• LUNGS

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Question 3 Eardrum

• How do these structures work?

• Answer
• A chain of events!
• 1. Sound waves enter the tympanum (eardrum)
• 2. The tympanum vibrates back and forth pushing
  and pulling the columella bone against the fluid
  filled sacks of the inner ear.
• 3. This fluid splashes which bends the sensory
  hairs so they can contact nerve fibers, which
  generate electrical impulses.
• 4. These impulses travel to the brain via the 8th
  nerve.

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Question 3 LUNGS

• The lungs, just as the eardrum, vibrate in
  response to external sound.
• Unbroken air link from lungs to eardrum serves
  two purposes
• Protection from its own calls
• Direction of external sound

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Protection

• Asymmetrical Pressure-Gradient Receiver
• Sounds arrive internally via two routes
• Unbroken air link (from lungs to eardrum)
• Sounds enter through the opposite ear

Unequal Pressure
Equal Pressure
Internal
Lungs opposite ear
External

Eardrum vibrates only with a small vibration
amplitude due to the equalized pressure.
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Direction

• The frog is able to distinguish direction through
  pressure differences on the eardrum and lungs.
  The greatest pressure will be felt on the side in
  which the sound originates.

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Question 4

• How is the morphology/physiology connected to the
  
• communication in frogs?

• Answer
• The structure is appropriate for the extremely
  loud calls that are produced by frogs.

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Production of Sound

• Male frogs vocalize by squeezing their lungs with
  their nostrils and mouth shut. Air flows over
  their vocal chords and into their vocal sacs.
  This causes the vocal sacs to blow up like a
  bubble.

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Types of Calls

• Male and female frogs produce a series of
  vocalizations that can be grouped into four
  principal type
• 1. Advertisement call courtship call,
  attracting females, territorial call encounter
  call
• 2. Response call produced in some species by the
  females in response to advertisement of males
• 3. Release call produced by males or unreceptive
  females in response to a tentative of amplexus
• 4. Distress call produced by many species in
  response to disturbance

http//www.fiu.edu/acaten01/repmod2.html
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Frog Calls
Advertisement Call
Rana clamitans
Green Frog
Release call
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Specializations

• A variety of properties can be used by frog
  species to recognize the vocalizations of their
  own species
• call rate
• call duration
• amplitude-time envelope
• waveform periodicity
• pulse-repetition rate
• frequency modulation
• frequency and spectral patterns.

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Frequencies

• Each call is unique from any other frog species
• Large frogs have deep voices (low frequency)
• Small frogs emit high chirps (high frequency)
• Frogs in cold temperatures emit sounds
  at slower rates due to slow muscle activity

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Conclusion

• In striving to be heard by rivals and mates,
  these amphibians have evolved a plethora of
  complex strategies.
• Peter M. Narins

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References

• Frog Calls. An Introduction to the Natural
  History of the Frogs and Toads in Ohio. (2000).
  p. 1. Online. Internet. Available
  http//www.cmnh.org/collections/vertzoo/frogs/call
  s.html
• Holliday, April. Frogs Can Hear Without Ears.
  USA Today. 26 April 2001.
• Online. Internet. Available
• http//www.usatoday.com/news/science/wonderquest/
  2001-04-25-frog-ears.htm.
• Narins, Peter M. Frog Communication.
  Scientific American. August 1995. pp. 78-83.
• The Calls of Frogs and Toads of Texas. 10
  January 1997. Online. Internet. Available
  http//www.zo.utexas.edu/research/txherps/frogs/ca
  lls.html
• Wray, John. Biologist's Research Shows How
  Peepers' Chorus is Linked to Survival. Advance.
  15 April, 2002. Online. Internet. Available
  http//www.advance.uconn.edu/02041509.htm

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• TOP TEN REASONS WHY IT'S GREAT TO BE A FROG
• 10. Babes are always kissing you because they
  think you'll turn into a prince.9. Flies in your
  soup are a bonus.8. You're above toads on the
  food chain.7. Green goes with absolutely
  everything!6. Pond Scum is a term of
  endearment.5. Most restaurants have a "no
  croaking" section.4. Amphibians are at a minimum
  risk of appearing on Geraldo.3. You can scratch
  hard to reach places with your tongue.2. You can
  donate your body to science for big bucks!1. It
  sure beats being a newt.

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QUESTIONS ?