Chapter 9: Marine Reptiles,
Birds, and Mammals
Vertebrates
350 m.y.a. vertebrates invaded land
Decendents of bony fish
Land vertebrates had to adapt to harsher conditions
on shore
Tetrapods had to develop lungs that allowed for
absorption of oxygen directly from air.
Tetrapods had to evolve in ways to keep from drying
out.
Amphibians, early tetrapods, have eggs that are
vulnerable. They need to stay moist and lay
them in water.
Reptiles on the other hand solved the problem of
waterloss, resulting in the evolution of birds and
mammals.
One they were equipped with adaptations for
land they reentered the ocean.
Classification
Marine Reptiles
•7000 species
•Dry skin with scales
•Eggs leathery shell
•Poilkilotherms (body temp varies w/environment)
and ectotherms (lose metabolic heat to environment)
Sea Turtles
•Shell, carapace, is fused with their backbone.
•Cannot retract their heads into the shell
•Legs are modified into flippers for swimming
•Warmer waters
Feed on seagrass, seaweed,
sponges, sea squirts,
barnacles, jellyfish
Must return to land to
reproduce
Migrate to original beach,
possible use of magnetic
fields
Return every 2-4 years,
copulate offshore, females
come on shore at night, dig a
hole lay between 100 – 160
eggs, hatch approx. 60 days
7 (8) species of Sea Turtles (all classified as
threatened);
Green (Chelonia mydas)
Hawksbill (Eretmochelys imbricata)
Leatherback (Dermochelys coriacea) D.o.d,largest turtle
Kemp’s Ridley (Lepidochelys kempii)
Loggerhead (Caretta caretta)
Flatback (Natator depressa)
Black (Chelonia agassizii)
Olive Ridley (Lepidochetys olivacea)
Green Sea Turtle
Hawksbill Sea Turtle
Flatback Sea Turtle
Black Sea Turtle
Kemps Sea Turtle
Loggerhead Sea Turtle
Leatherback Sea Turtle
Olive Ridley
Sea Snakes
Approx. 55 species
found in tropical
waters
Laterally flattened
and tail paddleshaped for
swimming, 3-4ft
long
Mate in the ocean,
ovoviviparous
Closely related to
cobras, rarely
aggressive
Marine Iguana (Amblyrhynchus cristatus)
Galapagos Islands
Eats seaweed and can dive 33ft to graze
Saltwater Crocodiles (Crocodylus porosus)
Mangroove swamps and estuaries
20-33ft long, very aggressive
Seabirds
Endothermic
Waterproof feathers
Hollow bones
Hard-shelled egg
Spend significant amount of time in marine environment
and eat marine organisms
Penguins
Flightless, wings modified into stubby flippers
Bones are denser to reduce buoyancy
Layer of fat and dense waterproof feathers
Feed on fish, squid, and krill
Lay eggs during cold times of year to ensure food
availability when egg hatches
Emperor penguin (Aptenodytes forsteri) mate for life
Tubernoses
Large group with distinctive tube-like nostrils and
heavy beaks usually curved at tip
Spend months and sometimes years at sea
Salt glands are used to get rid of excess salt
Albatrosses (Diomedea) glides almost never flap,
wing span 11ft
Shearwaters (Puffinus) and Petrels (Pterodroma)
Skillful, catch fish at sea
Faithful mates, elaborate mating rituals
Nest in remote islands and cliffs
Incubation and care for single chicks can take
up to 8 months
Fig. 9.7
Pelicans and Related Birds
Webbing between all four toes
Large fish eaters, widely distributed
Pelicans (Pelecanus) unique pouch below their
beaks, plunge into water to catch fish in its
pouch
Cormorants (Phalacrocorax) black long-necked,
dive to pursue their prey, float low in water with
only neck seen
Fig. 9.8
Frigate Bird
Narrow wings, long
forked talk
Pirates, very seldom
enter water feathers are
not very waterproof
Nest in large colonies
called rookeries,
creating large deposits
of guano (fertilizers)
Gulls and Related Birds
Gulls (Larus) the largest variety of seabirds, common
and widespread
Predator and scavengers
Terns (Sterna) graceful flyers, hover over their prey,
slender beaks
Puffins, Razorbill, Great Auk cold water species
Shorebirds
Wading, do not have webbed feet
Live inland as well as sea
Plovers, sandpipers, rails, coots, herons, egrets,
and even ducks
Marine Mammals
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200 m.y.a
Class Mammalia evolved from extinct reptiles
4600 species of mammals
Endotherms and homeotherms
Hair, mostly viviparous (embryo receives nutrients
and oxygen through the placenta, mammary gland
• Larger brain, live anywhere air to breathe and food to
eat
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Pinnipeds – Order Pinnipedia
Paddle-shaped flippers for swimming
Predators, fish and squid
Streamlined bodies
Coldwater, thick layer of fat (blubber)
Breed on land
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Seals
Largest group, rear flippers that cannot be moved
forward
They move on land with front flippers
Harbor Seals (Phoca vitulina)
Elephant Seals (Mirounga)
Sea Lions and Fur Seals
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Eared seals
Move their rear flippers forward
Use all fair limbs to walk/run on land
Graceful swimmers
Males much larger than females, massive head and
hairy mane
• California sea lion (Zalophus californianus)
Walrus (Odobenus rosmarus)
• Tusks are used for defense
• Feeds on invertebrates that it sucks up from the sea
bottom
• Dependent on sea ice
Odobenus rosmarus
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Sea Otter and Polar Bear
Order Carnivora
Sea Otter (Enhydra lutris)
Smallest marine mammal averages between 60 – 80
pounds
Lacks layer of blubber instead uses air trapped in its
dense fur
Breed and give birth in water, eats up to 30% of its
body weight/day (invertebrates and fish)
Lives in kelp beds
Polar Bear (Ursus maritimus)
• Semi aquatic animals that live in the Arctic and feeds
primarily on seals
• Depends on sea ice for survival
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Manatees and Dugong (sea cows)
Order Sirenia, relatives of elephants
Pair of front flippers, no rear limbs
Paddle – shaped horizontal tail
Blubber, live in shallow coastal waters
Strict vegetarians, large in size Dugongs (10ft) and
Manatees (15ft)
Manatee (Trichechus)
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Whales, Dolphins, and Porpoises
Order Cetacea, largest group
Many legends, art, and literature come from these animals
Bodies are streamlined, breath air, warm-blooded, have hair,
and produce milk for their young
Front flippers, no rear limbs (present in embryonic stage
only)
Many have dorsal fin, muscular tail fin-like (fluke)
Blubber, provides insulation and buoyancy
Single or double opening on the top of their head –
blowhole
90 species, all marine except 5 freshwater dolphin species
Divided into two groups; toothless and toothed
Fig. 9.15
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Baleen (toothless) whales, Mysticeti
Rows of flexible, fibrous plates (baleen) hang from
upper jaws made up of keratin and bristles overlap
Largest whales, 13 species
Blowhole has two openings
Blue Whale (Balaenoptera musculus)
Largest, males up to 80ft and females up to 110ft
Weigh up to 90 – 140 tons
Feed by gulping up schools of fish and swarms of
krill, Grey Whales are bottom feeders
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Toothed Whales, Odonticeti
80 species, teeth are adapted for diet of fish, squid,
and other prey that they can catch and hold
Food is swallowed whole not chewed
Blowhole has one opening
Largest toothed whale is the sperm whale (Physeter
catadon) at 42 tons
Killer Whale (Orcinus orca)
Fig. 9.18(Contd.)
• Small toothed whales are called dolphins or porpoises.
Dolphins tend to be classified by their distinctive
beaks and porpoises have more blunt shorter “noses”.
They are very social and move in pods.
• Bottlenose (Tursiops truncatus)
Whaling
Early as 6000 B.C.
Blubber used to make soap and lamp oil
Baleen used for corsets
Meat
•1800s harpoons and
steamships made whaling
easier
•The problem with whaling
was that whales are longlived mammals, had low
reproductive rate, and were
slow swimmers
•Factory ships made
whaling more efficient
•Whaling reached it peak in
1930s
• Right Whales were named so because they would
float after being harpooned
• 1946, from the decline in whale populations, 20
whaling nations established International Whaling
Commission (IWC) in attempt to regulate whale
hunting
• IWC collected data and set annual quotas
• Marine Mammal Protection Act of 1972, US
Congress banned the hunting of all marine mammals
in the US waters and importation of marine mammal
products (except in traditional fisheries of AK natives)
Pacific whitesided dolphin
drowned after
getting caught in
a drift net in the
North Pacific,
today MMPA has
enforced the use
of dolphin – safe
methods
Tab. 9.2
Biology of Marine Mammals
Swimming
• Streamline
• Use their flippers, tails and flukes up and down
• Cetaceans have blowhole on the top of their head that
allows them to breathe even though most of their body
is underwater
• Also means that cetaceans can eat without worrying
about drowning, to avoid inhaling water cetaceans
take very quick breaths
• Cetacean spout or blow can be seen at great
distances. The spout is filled with mucus and
warm seawater. The height and angle of the
spout can help identify whales.
• To keep warm in the cold water, whales have a
thick layer of blubber
Fig. 9.25
Diving
• Marine mammals can make the most prolonged dives
and go to considerable depths for their food.
• Adaptations for these deep prolonged dives include
the efficient exchange of air on the surface, the
storage of more oxygen in the blood and muscles, a
reduction of the blood supply to the extremities, and
collapsible lungs to help prevent the bends.
• Marine mammals have higher concentrations of
hemoglobin and myoglobin, which help them store
more oxygen.
Fig. 9.26
• They also slow their heart rate down conserving
oxygen and ensuring the flow to vital organs, like the
brain and heart.
• In the absence of oxygen, marine mammal muscles
begin anaerobic respiration, which results in the build
of lactic acid in their muscles that they have evolved
to be tolerance to.
• Marine mammals have adapted methods to prevent
from getting the bends.
• The bends or decompression sickness is a painful
condition caused when nitrogen dissolves in blood.
• The bubbles caused as a result of ascending can
become lodged in the joints or blood vessels
preventing the circulation of blood.
• Mammals have evolved so that their lungs actually
collapse as they dive.
• They have a flexible rib cage that gets pushed in by
the pressure of the water, as the lungs are compressed
air is pushed into a central location where nitrogen is
not readily absorbed.
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Echolocation
Marine mammals have excellent vision, but they
really rely on their echolocation. Echolocation is
based on hearing. Nature’s Sonar
Marine mammals echolocate by emitting sound waves
and listen for the echoes to reflect back from
surrounding objects. Their brain then analyzes the
echoes.
Echolocation is used to find prey and orient to their
surroundings.
Short bursts of sharp clicks
Fig. 9.27
• Cetaceans produce these sounds as air is forced
through the air passages and several associated air
sacs while the blowhole is closed.
• A fatty structure on the forehead of toothed whales,
the melon, may be used to focus and direct outgoing
sound waves.
• In the sperm whale, the huge forehead is filled with a
massive melon called the spermaceti organ. It
produces a waxy oil, called spermaceti.
• There are many theories for the actual function of this
organ; regulate buoyancy, absorb excess nitrogen
during deep dives.
Behavior
• Marine mammals, particularly cetaceans, use a rich
variety of vocalizations and tactile and visual signals
to communicate with each other.
• Play behavior and mutual assistance are additional
evidence of the complexity of their behavior.
Fig. 9.28
Fig. 9.30
Stranding or beaching
Migration
Most great whales migrate from winter
breeding areas in the tropics to summer
feeding areas in colder waters.
Reproduction
The reproductive system of marine
mammals is similar to land mammals.
Delayed implantation allows pinnipeds to
time the birth of pups with the arrival of
pregnant females in breeding areas.
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Reproduction cont’d
Little is known about cetacean reproduction.
Gestation lasts for 11 to 12 months in most cetaceans.
Calves are born tail first which allows for the placenta
to stay attached as long as possible, so that the calf
will have oxygen until it is fully born and can reach
the surface of the water.
They can live more than 40yrs.
Tab. 9.3
Green Turtle