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CHAPTER 14 Animals of the Pelagic Environment
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How to avoid sinking Increase buoyancy Gas containers
How to avoid sinking Increase buoyancy Gas containers Rigid container such as shells (internal or external) or… Swim bladder Fig. 14.2
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How to avoid sinking Float – less dense than SW or neutral
How to avoid sinking Foraminifers Float – less dense than SW or neutral Microscopic zooplankton have shells or tests Radiolarians Foraminifers Copepods Macroscopic zooplankton may have oil droplets Krill (resemble mini-shrimp or large copepods) Fish egg with oil droplet Krill
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Figure 14.6
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How to avoid sinking Floating macroscopic zooplankton Cnidarians
Hydrozoan (Portuguese man-of-war) gas-filled float Scyphozoan (jellyfish) soft low-density bodies
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Figure 14.7a
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How to avoid sinking Active swimming
Active swimming Fish – swim by curving body from front to back Fig. 14.9
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How to avoid sinking Active swimming – Squid
Unknown deep sea squid Active swimming – Squid Swim by trapping water and expelling it Also swim by using fins
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How to avoid sinking Active swimming sea turtles use flippers
marine mammals use up/down tail movements Sperm whale
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Fin designs in fish Vertical fins as stabilizers – dosral and anal fins Paired pelvic fins and pectoral fins for “steering” and balance Tail fin (caudal) for thrust
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Fin designs in fish Rounded caudal fins flexible, maneuver at slow speeds Truncate fins and forked fins, useful for both maneuvering and thrust Lunate fins rigid, lots of thrust for fast swimmers Heterocercal fins asymmetrical, lift for buoyancy (shark)
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Fin designs in fish Fig a
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Adaptations for finding prey
Adaptations for finding prey Mobility Lungers wait for prey and pounce (grouper) Mainly white muscle tissue Cruisers actively seek prey (tuna) Mostly red muscle tissue
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Adaptations for finding prey
Swimming speed Speed generally proportional to size Can move very fast for short time (mainly to avoid predation)
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Adaptations to finding prey
Most fish cold-blooded but some are warm-blooded Homeothermic-body temperature above sea water temperature Modifications in circulatory system Mainly in fast-swimming fish
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Adaptations of deep-water nekton
Mainly fish that consume detritus or each other Lack of abundant food Bioluminescence Fishing lures Large, sensitive eyes Anglerfish w/ males Lanternfish
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Adaptations of deep-water nekton
Large sharp teeth Expandable bodies Hinged jaws Gulper eel
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Adaptations of deep-water nekton
Fig
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Figure 14.12
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Adaptations to avoid predation
Schooling “Safety in numbers” School may appear as single larger unit Schooling maneuvers confuse predator
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Marine mammals Land-dwelling ancestors Warm-blooded Breathe air
Marine mammals Land-dwelling ancestors Warm-blooded Breathe air Hair/fur Bear live young Mammary glands for milk
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Marine mammals Carnivora Prominent canine teeth Sea otters Polar bears
Marine mammals Carnivora Prominent canine teeth Sea otters Polar bears
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Marine mammals Carnivora Pinnepeds Walruses Seals
Marine mammals Carnivora Pinnepeds Walruses Eat crustaceans with tusks Seals
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Marine mammals Carnivora Pinnepeds Sea lions Fur seals
Marine mammals Carnivora Pinnepeds Sea lions Fur seals
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Marine mammals Sirenia Herbivores Manatees
Marine mammals Sirenia Herbivores Manatees Coastal areas of tropical Atlantic Ocean Dugongs Coastal areas of Indian and western Pacific Oceans
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Marine mammals Cetacea Stream-lined bodies for fast swimming
Cetacea Stream-lined bodies for fast swimming Specialized skin (dermal ridges) structure for fast swimming Whales Toothed - carnivores Baleen – filter feeders
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Cetacea Fig
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Marine mammals Dolphins vs. porpoises Dolphins (Delphinidae)
Marine mammals Dolphins vs. porpoises Dolphins (Delphinidae) 35 species Beaks melon (fatty organ in forehead) Prominent, curved dorsal fin conical, undifferentiated teeth Range in size from 1.5 m Hector's dolphin to 9 m killer whales Porpoises (Phocoenidae) 6 species Lack prominent beak laterally compressed teeth More triangular dorsal fin Bottlenose dolphin Harbor porpoise education/images/harbourporpoise/teeth2_small.gif
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Cetacea Adaptations for deep diving Use oxygen efficiently
Cetacea Adaptations for deep diving Use oxygen efficiently Able to absorb 90% of oxygen inhaled Able to store large quantities of oxygen Able to reduce oxygen required for noncritical organs Muscles insensitive to buildup of CO2 Collapsible lungs
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Adaptations for deep diving
Sperm whales can dive up to 1 hour, 52 min. and to 3 km deep
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Cetacea Suborder Odontoceti (toothed)
Cetacea Suborder Odontoceti (toothed) Dolphins, porpoises, killer whale, sperm whale Echolocation to determine distance and direction to objects Clicks produced in nasal air sacs are focused by the melon Echos received thru lower jaw middle ear Determine shape, size of objects
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Intelligence in toothed whales
Intelligence in toothed whales Large brains relative to body size Communicate with each other Brains convoluted Trainable Are they intelligent?
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Cetacea Suborder Mysticeti Baleen whales
Fig Right whale baleen Baleen whales Blue whale, finback whale, humpback whale, gray whale, right whale Fibrous plates of baleen sieve prey items Vocalized sounds for various purposes Right whale feeding
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Gray whale migration 22,000 km (13,700 mi) annual migration from coastal Arctic Ocean to Baja California and Mexico Feeding grounds in Arctic (summer) Breeding and birthing grounds in tropical eastern Pacific (winter) Fig
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Whales as endangered species
Fewer whales now than before whaling International Whaling Treaty Hunting of gray whale banned in 1938 Gray removed from endangered list in 1993 as population rebounded Fig
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Marine reptiles Sea turtles Prey depends on species
Marine reptiles Green Sea turtles Prey depends on species Greens eat seagrass (gut flora digests cellulose) Loggerheads eat conch Leatherbacks eat jellyfish Nest on beaches: predation, lights on dunes Many overexploited Loggerhead Leatherback
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Marine iguanas of Galapagos Islands
Feed on submerged algae Dive for up to 20 minutes Must surface before they become too cold and can’t climb out of water
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Truly aquatic - reproduce in water - live-bearers
Sea snakes of Pacific Highly poisonous Truly aquatic - reproduce in water - live-bearers
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End of CHAPTER 14 Animals of the Pelagic Environment
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