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Swimming & Diving
Swimming, Diving & Echolocation
1
Swimming
• Most representatives have streamlined bodies
o Notable exceptions are the polar bear and sea otter
• Pinnipeds swim using mainly their flippers
o Some sea lions can swim up to 22 MPH
• Cetaceans and sirenians swim using flukes in a
vertical fashion
Swimming, Diving & Echolocation
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Swimming
• To avoid inhaling
water all marine
mammals take quick
breaths
o Fin whales can empty
and refill its lungs in
less than 2 seconds
o This is ½ the time we
take
Swimming, Diving & Echolocation
• Cetaceans have the
advantage of having
a blowhole on top of
the head
o This allows them to
breathe with most of
the body remaining in
the water
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Diving Physiology
• Marine mammals have mastered the art of diving, this allows
them to exploit food at considerable depths
Sea otters – 4 to 5 min. up to 180 ft.
Northern elephant seal – capable of depths of 5,000 ft.
Weddell seal – 1 hr & 13 min. and 1,900 ft.
Baleen whales do not dive deep and seldom dive deeper than 300
ft.
 Toothed whales are excellent divers
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• Dolphins can dive 990 ft
• Sperm whales can dive for over an hour at 7,400 ft
Swimming, Diving & Echolocation
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Diving Physiology
• Have more blood than
non-diving mammals with
a higher concentration of
hemoglobin
• Muscles are extra rich in
myoglobin which allows
for more oxygen to be
stored
Swimming, Diving & Echolocation
5
The Dive Reflex
• Heart rate slows dramatically
o Bradycardia
• Blood flow to non-essential body parts is
reduced allowing blood to be used where it is
needed most
• Vasoconstriction offsets dramatic drop in
blood pressure
• Water pressure collapses a flexible rib cage
forcing air out of the lungs
Swimming, Diving & Echolocation
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Echolocation
• Marine mammals depend very little on smell, but
do have good vision
• Most have a sensory system based on hearing
o All toothed whales, some pinnipeds and baleen whales
• Echolocation is natures version of sonar
Swimming, Diving & Echolocation
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Echolocation
Nice Melon!
• Melon - fatty structure
found on the head
o Focuses and directs sound
waves
• Sound is received by
hollow oil/fat filled lower
jaw
o Sound passes to two very
sensitive inner ears
Swimming, Diving & Echolocation
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