Marine Mammals
Order Cetacea & Sirenia
Classification and Characteristics
Order Cetacea & Sirenia
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Order Cetacea
• Mysticeti (Baleen whales)
• Odontoceti (Toothed whales)
• Have made the most complete transition to
aquatic life
 Have considerable morphological and ecological
variability, but all share similar characteristics
• Convergent evolution – different spp. develop similar
structures due to a similar lifestyle
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Cetacea Characteristics
• Elongated telescoped skull
• Nostrils are on top of the
head instead of in front,
forming a single or double
blowhole
• Have a pair of front flippers,
but the rear limbs have
disappeared
o Flukes are used for propulsion
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Suborder Mysticeti
• Toothless or baleen whales, 11 spp.
• Filter feeders which use baleen
• Posses symmetrical dorsal skull with 2 blow
holes
• Are the largest whales and the largest animals
that ever lived on earth
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The Roqurals
• Includes: blue, fin,
minke, and humpback
• Feed by gulping large
schools of krill or
small fish
o The lower part of the
throat has grooves on
the underside which
distend when feeding
Blue Whale
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The Right Whales
• Includes: Bowhead
and right whales
• Swim at the surface
with their mouths
open
Northern Right whale
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Mysticeti Feeding Types
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Suborder Odontoceti
• Includes: Sperm whales, narwhals, beaked whales,
oceanic dolphins, true porpoises, and river dolphins
• Have teeth, adapted for a diet of squid, fish and
other marine mammals
• Dorsally asymmetrical skull with a single blow hole
• More variable morphologically and ecologically
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Sperm Whale
• Largest of the toothed
Whales on earth
(Physeter catodon)
o Eat squid, especially from
great depths
o Squid beaks and other
undigestibles accumulate
in the gut creating
ambergris
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Killer Whale
• Orcinus orca is common
in cold water, worldwide
• Two distinct groups of
killer whales
o Piscivores
o Marine mammal
carnivores
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Dolphins & Porpoises
• Dolphins
o Falcate dorsal fin
o Conical teeth
o Distinct beak
• Porpoises
o Triangular dorsal fin
o Spade shaped teeth
o Lack a beak
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Order Sirenia
• Inhabit shallow water and feed strictly on
plants
o Herbivores - digestive tract is similar to
horses and elephants
• Use a prehensile upper lip to feed
• Occupy tropical and subtropical waters
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Is it the Rum, or are you
beautiful?
• Have been exploited for
their meat (tastes like
veal) and oil- rich blubber
• Reproduce slowly 1 calf
ever 3 years
• Only four species remain,
all close to extinction
• Dugongs – 10 ft. and 930 lb.
(East Africa to some pacific
islands)
• Manatees – 15 ft and 1,320 lb.
Order Cetacea & Sirenia
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