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Chapter 14 Animals of the Pelagic Environment. Essentials of Oceanography 7 th 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.
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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 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