10/29/13
Adaptations of marine
mammals
• Hair!
• Internal mammary glands
• Heat retention (blubber/fur) –
endotherms
• Respiratory rates-decreased
• High blood volume
• Fusiform bodies
• K-selected
• Good vision (generally)
• The role of acoustics
• Counter current heat exchange
• Tend to get large (why?) • Some have delayed implantation
(embryo)
Counter current heat exchangers revisited
• Blood in the arteries runs deep (not near the
surface)
• As it passes by cooler veins, it
gives up some of its heat, warming
up the veins. • In this way, heat can be ‘trapped’
within areas where it is needed
Adaptations
Remember these are MAMMALS
• Internal mammary glands
• Heat retention (blubber/fur)
• Respiratory rates-decreased
• Fusiform bodies
• K-selected
• Good vision (generally)
• Counter current heat exchange
• Haul-out • Molting
ORDER PINNIPEDIA (suborder of
carnivora)-winged foot: seals, sea lions,
walruses
Families: • Phocidae (seals)
• Otariidae (sea lions) and • Odobenidae (walruses)
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Phocidae
• Internal testes
• Hind flipper propulsion
• No external ears
• Can t really walk on fore flippers
like sea lions can
• Deeper divers
• Squid eaters (primarily)
Elephant seals
•  Beach breeders territorial
•  Polygynous – with
dominant males
•  Males can weigh up to
5500 lbs (8500 in the S.
Elephant seal!) and be
15-20 feet long
•  Females are much
smaller – 10 feet and
1500-2000 lbs
•  Sexual dimorphism
Elephant seals can dive to extreme depths – up to 1500 meters!
(over 3,000 feet), and hold their breath for 20-60 minutes.
They have large blood volume, use myoglobin to carry oxygen, and
can lower their heart rate to less than 9 beats per minute
Otariidae: sea lions
Breeding - colonies
• Long fore-flippers
• Can walk and maneuver well on
their fore flippers
• Swim underwater with fore
flippers
• External ears (pinnae)
• External testes
• More recently evolved
Sea Lions spend more time with their young
• Fish eaters
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Breeding - ice
Seals wean early
1-4 weeks after birth
Parental investment is high
though – milk can more than 50%
milkfat
Ice breeders tend to be monogamous, and have far less sexual
dimorphism. This is in part because ice territories are more difficult
to defend, unlike beach territories
There are of course
always exceptions…
Odobenidae: walrus
• Internal testes
• No external ear flaps
• Flippers like a sea lion (large fore flippers)
Hooded seals exhibit
sexual dimorphism – the
males have a secondary
sexual characteristic to
attract females
• Use their large teeth (tusks) to dredge the bottom for
molluscs and other invertebrates
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Other marine mammals
Mustelidae
Sea Otters:
Enhydra Lutris Nereis
Returned to the sea about 15 MYA
Feeding:
Feed on a variety of invertebrates (CA)
Play an important role maintaining the
ecology of kelp forests
Mothers pass food preference to her
offspring
Tool users!
Keystone predators
Mother stays with pup for about
1 yr. Gives birth every 1-2 years
Reproduction:
Males are sexually mature at about 5-6 yrs
Females 4-8 yrs
8 month gestation
Delayed implantation
Pups can swim at about 4-6 wks
Can forage on their own at about 6 months
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This year s pup counts were
the lowest since 2003
Ursus maritimus
Polar Bears
Ursus maritimus
They live in the Arctic.
They hunt seals in sea ice leads
Status – threatened, but data deficient. ~20,000?
Closely related to the brown bear (Grizzly)
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Males – up to 1200 lbs!
Females up to 600 lbs
Cubs (twins) are born in Nov-Dec
Emerge from the Den in April!
31% milkfat
2.5 year dependency
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