Whale Notes

Cetaceans = “Whales” in Latin

How Whales Became the Largest Animals on The Planet

• Largest group of marine mammals

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• Two major groups
• Odontoceti = toothed whales – 74 different species
• Mysteceti = Baleen whales – 10 species

Whales Bubble Netting

Adaptations for Breathing and Diving

• Cetaceans exhale up to 80-95% of the air in their lungs (human 15-25%)
• Huge diaphragm muscles and more floating ribs
• A rorqual can exhale and inhale 1500 gallons of air in one breath (human about 4 seconds for a pint)

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Adaptations for Diving

Mammalian Diving Reflex (1^st 2 of these occur in humans)

Triggered by cold water hitting the face

• Bradycardia (slowing of the heartbeat by 15 to 50%)
• Peripheral vasoconstriction –
• Blood supply is reduced to less essential areas and redirected to vital organs
• Blood shift that occurs during very deep dives
• Organ and circulatory walls allow plasma/water to pass freely throughout chest and abdominal cavity
• This keeps pressure constant and organs are not crushed
• The lungs will fill with blood plasma which gets reabsorbed as animal leaves pressurized environment

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Extended Diving Adaptations

• Substantial amounts of myoglobin and large volumes of blood
• Great deal of oxygen and glucose can be stored
• Myoglobin is like hemoglobin except that it binds with oxygen far more readily and is found in the muscle tissue

Extended Diving Adaptations

• Lungs and sinuses are very flexible allowing air spaces to compress without pain

Ocean Acoustics

• Sound travels 5x’s faster in water than air
• Warmer water = faster
• More pressure = faster

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• What are similar and different about these two sets of sound waves?

The SOFAR Channel

• Sound in the sea can be “trapped” by temperature and pressure differences of the ocean at different depths
• Sound is influenced by temp in the upper layers
• By pressure at depth
• Sound waves bend towards area of slowest sound speed
• Low frequency sounds can travel across entire ocean basins

bump           bump        bump      bump     bump  bump

http://www.dosits.org/science/sndmoves/4a.htm

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http://www.oceanexplorer.noaa.gov/explorations/sound01/background/seasounds/seasounds.html#fin

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Echo-Location and Vocalization

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• Many cetaceans can echo-locate to determine:
• Object size
• Distance
• Density
• Position
• Can distinguish between a kernel of corn and a ball bearing at 50 ft

Melon is used like a lens to direct sounds

Object detection with sound

• In order for an object to be detected it must be ¼ to 1/5 the length of the sound wavelength
• Dolphin click 100kHz = wavelength of app.1.5cm (small rocks and fish)
• Blue whales can produce sounds below human hearing

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• Sounds with very long wavelengths are used to discriminate large objects

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