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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 containersSwim bladderAbility to float
Figure 14-1
Figure 14-2
Gas containers in cephalopods
Swim bladder
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 carbonateTest is segmented or chambered
Figure 14-4
Microscopic floating organisms: Copepods
Copepods have a hard exoskeleton and a segmented body with jointed legsRelatives 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 cruisersLungers sit and wait for prey to come close by
Cruisers actively seek prey
Cold-blooded versus warm-bloodedMost 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 devicesBioluminescenceLarge, sharp teethLarge mouths and expandable bodiesHinged 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 sizeSparse hair all over bodyVegetariansToenails (on manatees only)
Includes:ManateesDugongs
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
Figure 14-22
Killer whale jawbone
Generation of Odontoceti echolocation clicks
Figure 14-23
Odontoceti echolocation
Sound is bounced off objects to determine:
SizeShapeDistanceInternal 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 MexicoSpend summertime feeding in highly productive Arctic waters
Figure 14-27
End of Chapter 14
Essentials of Oceanography
7th Edition