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CHAPTER 14
Animals of the Pelagic Environment
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Chapter Overview
• Pelagic animals use a variety of
adaptations to help them survive.
• Marine mammals share similar
characteristics with land mammals.
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Adaptations…..
• Ability to float
– Zooplankton – some produce fats or oils to
stay afloat
• Ability to swim
– Nekton – larger fish and marine mammals
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Microscopic Zooplankton
–Radiolarians
–Foraminifers
–Copepods
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Copepods
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Macroscopic Zooplankton
• Krill
– Resemble mini shrimp
or large copepods
– Abundant near
Antarctica
– Critical in Antarctic
food chains
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Floating Macroscopic
Zooplankton
Portuguese man-of-war
• gas-filled float
Jellyfish
• soft, low-density
bodies
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Swimming Organisms
• Fish, squids, sea
turtles, marine
mammals
• Swim by trapping
water and expelling it,
• Swim by curving body
from front to back
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Swimming Motion and General Fish
Features
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Adaptations for Finding Prey
• Lungers wait for prey and pounce
(grouper).
• Cruisers actively seek prey (tuna).
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Lungers and Cruisers
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Adaptations to Avoid Predation
• Speed
• Poison
• Hiding: Transparency, Camouflage and
Countershading-already discussed
• Schooling
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Adaptations to Avoid Predation
• Schooling
– Safety in
numbers
– Appear as a
larger unit
– Maneuvers
confuse predator
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Marine Mammals
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Land-dwelling ancestors
Warm-blooded
Breathe air
Hair/fur
Bear live young
Mammary glands for milk
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Major Marine Mammal Groups
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Order Carnivora
Prominent canine teeth
• Sea otters
• Polar bears
• Pinnipeds
– Walruses
– Seals
– Sea lions
– Fur seals
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Carnivora
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Seals vs. Sea Lions
• Seals lack ear flaps
• Seals have smaller
front flippers
• Different hip
structures
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Major Marine Mammal Groups
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Order Sirenia
Herbivores
• Manatees
– Coastal areas of
tropical Atlantic Ocean
• Dugongs
– Coastal areas of
Indian and western
Pacific Oceans
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Order Cetacea
• Whales, dolphins, porpoises
• Elongated skull
• Blowholes on top of skull
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Order Cetacea
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Order Cetacea
Suborder Odontoceti: Toothed whales)
– Dolphins, porpoises, killer
whale, sperm whale
– Echolocation for shape,
size of objects
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Echolocation
• Emit clicks and get
return
• Detect fish
• Can be used to stun
fish at close range
• Sperm whales hunt
giant squid
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Intelligence in Toothed Whales
• Large brains relative to body size
• Can communicate with each other
• Trainable
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Order Cetacea
Suborder Mysticeti: Baleen whales
• Blue, Finback, Humpback, Gray, Right whales
• Fibrous plates (baleen) sieve prey items
• Can vocalize sounds
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Use of Baleen
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Baleen Whale Families
• Gray whales
• Humpback whales
• Right whales
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Gray Whale Migration
• 13,700 miles from
coastal Arctic to Baja
• Feeding grounds in
Arctic (summer)
• Breeding and birthing
grounds in Baja
(winter)
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Gray Whales Feeding
• Turn on side
• Scoop bottom
• Sift sand and filter out
small crustaceans
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Gray Whale Friendly Behavior
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Baleen Whales
• Humpback whales
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Whales as Endangered Species
• Fewer whales now
than before whaling
• Hunting of gray whale
banned in 1938
• Gray removed from
endangered list in
1993 as population
rebounded
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Whaling
• International Whaling Commission (IWC) 1948 –
established to manage whale hunting
• In 1986, 72 IWC nations banned whaling
• Three ways to legally hunt whales:
– Objection to IWC ban-Norway
– Aboriginal subsistence whaling-Alaska
– Scientific whaling-Japan 1000’s of whales????
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Exploitation Status of Marine
Fish
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Overfishing
• 80% of available fish
stock fully exploited,
overexploited, or
depleted/recovering
• Large predatory fish
reduced
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Incidental Catch or Bycatch
• Non-commercial species are taken
incidentally by commercial fishers.
• Bycatch may be up to 8 times more than
the intended catch.
– Birds, turtles, dolphins, sharks
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Tuna and Dolphins
• Tuna and dolphins
swim together
• Caught in purse
seine net
• Marine Mammals
Protection Act
addendum for
dolphins
• Driftnets or gill nets
banned in 1989
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Purse Seine Net
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Fisheries Management
• Regulate fishing
• Create Self-sustaining ecosystems
• Enforcement difficult-International waters
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Fisheries Management
• Consumer choices in seafood
• Consume and purchase seafood from healthy, thriving
fisheries
– Examples: farmed seafood, Alaska salmon
• Ecosystem-based fishery management
• Avoid overfished or depleted seafood
– Examples: tuna, shark, shrimp
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Seafood Choices
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