Chapter 14
Animals of the Pelagic
Environment
Essentials of Oceanography
7th Edition
Pelagic organisms
Organisms that live in the pelagic
environment:
Live suspended within the water column
Can float or swim
Have adaptations that allow them to stay above
the ocean floor
Staying above the ocean floor
Adaptations
for staying
above the
ocean floor:
Rigid gas
containers
Swim
bladder
Ability to
float
Swim bladder
Figure 14-2
Gas containers in
cephalopods
Figure 14-1
Microscopic floating organisms:
Radiolarians
Radiolarians
produce a hard
test composed
of silica
Tests have
projections to
increase
surface area
Figure 14-3
Microscopic floating organisms:
Foraminifers
Foraminifers
produce a
hard test
composed of
calcium
carbonate
Test is
segmented or
chambered
Figure 14-4
Microscopic floating organisms:
Copepods
Copepods have
a hard
exoskeleton and
a segmented
body with
jointed legs
Relatives of
shrimp, crabs,
and lobsters
Figure 14-5
Macroscopic floating organisms:
Krill
Krill are related
to copepods but
are larger in size
Abundant in
Antarctic waters,
where they are a
favorite food of
the largest whales
Figure 14-6
Macroscopic floating organisms:
Coelenterates
Coelenterates
are soft-bodied
organisms
including:
Siphonophores
(Portuguese
man-of war)
Scyphozoans
(jellyfish)
Figure 14-7a
Swimming organisms (nekton)
Larger pelagic organisms can swim against
currents and often migrate long distances
Nektonic organisms include:
Squid
Fish
Marine mammals
Squid
Squid are
invertebrates
that swim by
taking water
into their body
cavity and
forcing it out
through their
siphon
Figure 14-8
Fish: Swimming motions and fins
Figure 14-9
Fish: Adaptations
Feeding styles: Lungers versus cruisers
Lungers sit and wait for prey to come close by
Cruisers actively seek prey
Cold-blooded versus warm-blooded
Most fish are cold-blooded
A few active fish are warm-blooded
Many fish school to avoid predators
Fish: Deep-water nekton
Adaptations of
deep-sea fish:
Good sensory
devices
Bioluminescence
Large, sharp teeth
Large mouths and
expandable bodies
Hinged jaws
Figure 14-11
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
Marine mammals: Order
Sirenia
Sirenian characteristics:
Large body size
Sparse hair all over body
Vegetarians
Toenails (on manatees only)
Includes:
Manatees
Dugongs
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
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
Odontoceti echolocation
Sound is
bounced off
objects to
determine:
Size
Shape
Distance
Internal
structure
Figure 14-24
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
Types of baleen whales
Baleen whales include three families:
Gray whale (a bottom-feeder with short
baleen)
Rorqual whales (medium-sized baleen)
Balaenopterids (blue whales, finback whales, and
other large whales )
Megapterids (humpback whales)
Right whales (surface skimmers with long
baleen)
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
End of Chapter 14
Essentials of Oceanography
7th Edition