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CHAPTER 14Animals 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

• 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