Marine mammals

Marine mammals
!  Characteristics of marine mammals:
!   Warm-blooded
!   Breathe
!
!
!
air
  Have hair (or fur)
  Bear live young
  Females have mammary glands that produce
milk for their young
Marine mammals: Order
Carnivora
!   All members of order
Carnivora have prominent
canine teeth
!   Includes:
Sea otters
  Polar bears
  Pinnipeds (flipper-footed)
! 
!
!
!
!
!
Walrus
Seals
Sea lions/fur seals
California sea lions
Figure 14-17c
Differences between seals and
sea lions/fur seals
!  Seals:
!   Lack
!
!
!
ear flaps
  Have small
front flippers
  Have claws
  Cannot rotate
hind flippers
beneath
themselves
Figure 14-18
Whales, dolphins and porpoises are cetaceans (Class Mammalia, Order Cetacea) Of all the marine mammals, cetaceans (and sirenians) have made the most complete transi9on to aqua9c life Spend their en9re lives in the water The bodies of cetaceans are streamlined and look remarkably fish-­‐like; an example of convergent evolu2on Convergent Evolu-on: Streamlining Convergent evolu9on is the process by which unrelated species evolve similar physical characteris9cs because they have similar lifestyles Whales, Dolphins, and Porpoises !  Cetaceans have a pair of front flippers, but the rear pair of limbs has virtually disappeared !   Remain in adults as small, useless bones –  Most cetaceans have a dorsal fin, like fishes –  Their muscular tail ends in a pair of fin-­‐
like, horizontal flukes Whales, Dolphins, and Porpoises !   Blubber provides !
cetaceans with insula9on   Cetacean nostrils are on top of the head, forming a single, or double opening called the blowhole !  There are ~90 species of cetaceans !  All are marine, except for 5 species of freshwater dolphins !  Cetaceans are divided into two groups: !   Toothed whales – includes dolphins & porpoises !   Baleen whales; toothless, filter-­‐feeding whales Photos property of the Riverhead Founda9on Marine mammals: Order
Cetacea
!  Cetacean characteristics:
!   Blowholes
!
!
on top of skull
  Skull telescoped (streamlined shape)
  Very few hairs
!  Includes:
!   Whales,
dolphins, and porpoises
Marine mammals: Order Cetacea
Figure 14-20
Two suborders of order Cetacea
!  Suborder Odontoceti (toothed whales)
!   Echolocate
!
(send sound through water)
  Includes killer whale, sperm whale, dolphins,
porpoises, and many others
!  Suborder Mysticeti (baleen whales)
!   Have
!
rows of baleen plates instead of teeth
  Includes blue whale, finback whale, humpback
whale, gray whale, and many others
Types of baleen whales
!   Baleen whales include three families:
Gray whale (a bottom-feeder with short
baleen)
Rorqual whales (medium-sized baleen)
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! 
!
!
! 
Balaenopterids (blue whales, finback whales, and
other large whales )
Megapterids (humpback whales)
Right whales (surface skimmers with long
baleen)
Mysticeti: The baleen whales
!  Mysticeti whales have baleen instead of teeth
!  Baleen plates:
!   Hang
!
!
!
as parallel rows from the upper jaw
  Are made of keratin
  Are used as a strainer to capture zooplankton
  Allows baleen whales to eat krill and small fish
by the ton
Baleen
Figure 14-25
Baleen Whales Baleen whales are characterized not only by their baleen, but by the double opening of their blowholes (double blowhole) Baleen whales can be further divided into the rorquals; rorquals feed by gulping up schools of fish and swarms of krill The lower por9on of the throat expands during feeding, along dis9nc9ve grooves BALEEN
The majority of cetaceans are toothed whales Toothed whales use their teeth only to catch and hold prey, not to chew it Toothed whales have a single blowhole (one opening) on the top of their head Though they are all whales, most of the small toothed whales are called dolphins or porpoises The Toothed Whale Whales !  The toothed “whales” include the sperm whale, beluga, pilot whales, beaked whales, and orca, each divided into their own families Differences between dolphins
and porpoises
!  Dolphins have:
!   An
!
!
elongated
snout (rostrum)
  A sickle-shaped
(falcate) dorsal fin
  Teeth that end in
points
Killer whale jawbone
Figure 14-22
Generation of Odontoceti
echolocation clicks
Figure 14-23
Echoloca-on Odontoceti echolocation
!   Sound is
bounced off
objects to
determine:
Size
  Shape
  Distance
  Internal
structure
! 
!
!
!
Figure 14-24
Marine mammals: Order Sirenia
!  Sirenian characteristics:
!   Large
!
!
!
body size
  Sparse hair all over body
  Vegetarians
  Toenails (on manatees only)
!  Includes:
!   Manatees
!   Dugongs
An example of migration: Gray
whales
!   Gray whales undertake
the longest annual
migration of any
mammal:
Spend wintertime in
birthing and breeding
lagoons in Mexico
  Spend summertime
feeding in highly
productive Arctic
waters
! 
!
Figure 14-27