Transcript chapter_9_powerpoint_im

Marine Reptiles, Birds, and
Mammals
Chapter 9
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Marine Reptiles
• Reptiles- have the ability to lay eggs on
land, and they have scaly skin to prevent
water loss.
• Reptiles are ectotherms, so they are more
common in temperate and tropical seas.
• Reptiles have lungs, so they must surface
to breathe.
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Sea Turtles- Order Chelonia
• Like land turtles- have a protective
carapace fused to their backbones.
• Unlike land turtles, they cannot retract
their heads and limbs into the shell.
• There are nine species- all are endangered
or threatened.
• Live primarily in warm waters.
• Must return to land to reproduce.
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Sea Turtles (cont’d)
• Green sea turtles- live in coastal waters, feed on
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seaweeds and seagrasses.
Nest every 2-4 years on the same beaches.
DNA tests show similarities in populations from
specific breeding grounds.
Baby sea turtles must cross the beach to get to
the sea.
Many predators such as crabs, dogs, shorebirds.
Temperature of nest determines sex of baby sea
turtles.
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Adult Sea Turtles
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Green Sea Turtle
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Hawksbill turtle
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Loggerhead sea turtle
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Baby Sea Turtles are called hatchlings
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Sea Turtle nest hatching
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The dangerous trip to the sea!
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Other marine reptiles
• Sea Snakes- Order Squamata.
• They are carnivores and eat small fish and
their eggs.
• Bear live young- they are ovoviviparous,
carrying their eggs until hatching.
• Live a totally marine existence- have a
laterally compressed body for swimming.
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Yellow Lipped Sea Snake
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Sea Snake
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Other Marine Reptiles- cont’d
• Marine Iguanas- Live only in the
Galapagos Islands.
• Lives mostly on the rocky shores of
these islands- dives and swims to feed on
seaweeds.
• Saltwater crocodiles- live in estuaries and
mangroves in the Indian Ocean, Australia,
and the west Pacific.
• Very Aggressive- known to attack
humans
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Galapagos marine iguana
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Galapagos Marine Iguana
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The White ‘wig’ is made of salt !
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Seabirds
• Birds (Class Aves) are homeotherms- they
maintain a constant internal temperature.
• Seabirds are any bird that feeds on marine
organisms.
• They must nest on land.
• They are only ~3% of all bird species.
• They require a LOT of energy!!!!
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Penguins
• Flightless birds with wings modified into ‘flippers’
• Have a layer of fat for insulation and waterproof
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feathers.
Live only in the southern hemisphere.
Many travel for miles to reach inland breeding
grounds.
Only the Galapagos penguin lives at the equator.
They hunt in the ocean for fish, krill, and squid.
Ex.- Emperor’s, Chinstraps, Adelie, Galapagos
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Emperor penguin chicks
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Adult Emperor Penguins
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Adelie Penguins
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Chinstrap Penguins
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Galapagos Penguins
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Tubenoses- Albatrosses and Petrels
• Can spend months or years at sea, only
return to land to breed.
• Have salt glands on their beaks for
excreting excess salt
• Albatrosses- have the longest wingspan of
any bird- up to 11 ft!
• Albatrosses and other tubenoses, mate for
life.
• Petrels and shearwaters are also in this
group
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Northern Royal albatross, and
Wandering albatross with chick.
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Waved Albatross
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Shearwaters flock by the thousands
for a feeding frenzy
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Buller’s Shearwater- off the coast of
New Zealand
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Pelicans, Cormorants, and Frigates
• Pelicans- dive and scoop fish out of the
water into a pouch.
• Once threatened by pesticide use (DDT)
• Cormorants- black birds that dive and
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chase their prey.
They sit low in the water, can sometimes be
seen drying their wings on docks
• Frigates- rarely touch the water, they steal
food from other seabirds midflight.
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Brown Pelicans
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Frigate birds- male displaying for females
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Cormorants
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Gulls and terns
• Gulls live in all 50 states, the most widely
distributed bird in North America.
• Gulls are scavengers and predators.
• They often will prey upon the nests and
young of other birds.
• Terns- Small graceful flyers, they hunt by
plunging into the water for small fish.
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Arctic Terns travel from the Arctic, where they
breed, to the Antarctic for feeding during the
summer- a yearly migration of over 24,000 miles!
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Common Tern and chicks
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Shorebirds
• Group that includes sandpipers, plovers
and all birds that live on the beach or
inlets.
• Often live in inland freshwater habitats as
well.
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American Oystercatcher
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Least Sandpiper- Monterey Bay, CA
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Piping Plover- a threatened species
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Beak shape
in birds is
related to its
food supply
and how it
hunts
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Figure 9.08
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Marine Mammals
• Mammals are homeotherms.
• Have hair instead of feathers for
insulation.
• They are viviparous, and nurse their
young.
• Have a large brain compared to their body
size.
• Five groups (orders and suborders) of
mammals inhabit the oceans
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Order Pinnipedia
• Seals, sea lions, and walruses.
• Closely related to the carnivora (cats,
dogs, bears)
• Predators-Feed on fish and squid.
• Live in cold waters. Have blubber for
insulation.
• Blubber also serves as a food reserve and
aids in buoyancy.
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Pinnipeds (cont’d)- Seals
• Seals- have posterior flippers that cannot
turn forward.
• Harbor seals are the most common in the
North Atlantic and Pacific.
• Monk seals are a rare warm water species.
• Elephant seals- can be 4 tons.
• Seals have been hunted for their meat and
oil, but are now protected in the U.S.
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Figure 9.09b
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Baby Harp Seals
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Pinnipeds (cont’d)- sea lions
• Sea lions have external ears and can move
their flippers forward.
• They can move more easily on land.
• California Sea Lion is the most common.
• Fur seals have been hunted extensively for
their thick fur.
• Walruses- feed on clams and other benthic
invertebrates. Easily identified by their
large tusks
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Fur Seal
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California Sea Lion
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South American Sea Lions
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Walruses have tusks for defense and
anchoring to the ice.
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Order Carnivora- Sea Otters
• The smallest marine mammal.
• The only marine mammals that lack a layer
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of blubber.
Insulation by trapping air in the thick fur.
Were at one time almost hunted to
extinction.
They breed and give birth in the ocean.
They live in kelp forests and are an important
part of the kelp forest ecosystem.
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Sea Otters
are playful
marine
mammals.
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Sea Otters
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Order Sirenia- manatees
• Have front flippers but no rear limbs.
• Strict vegetarians- feed on seaweeds and
grasses.
• Have been hunted to near extinction (the
Stellar’s sea cows are extinct)
• Seagrass beds threaten their food supply.
• Often injured by boats, all four species are
endangered.
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The Florida
Manatee is
protected
under the
Marine
Mammal
Protection
Act.
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Mother and calf- Manatees only
produce one calf every three years.
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Order Cetacea- Whales, dolphins
and porpoises
• Cetaceans have made the greatest
transition to marine living.
• Their bodies are a streamlined shapesimilar to fish.
• Convergent evolution- when different
species evolve similar characteristics due
to similar lifestyles or environments.
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Convergent evolution in marine
vertebrates
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Order Cetacea
• Have front flippers- rear limbs have
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disappeared.
Rear limbs exist only in early embryonic
stages.
Instead of a caudal fin, cetaceans have a pair
of horizontal flukes.
Have almost no hair, but have blubber for
insulation.
Nostrils have moved to the top of the head.
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Early
cetacean
embryo
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Baleen whales- Suborder Mysticeti
• Toothless whales- have rows of flexible,
fibrous plates that hang from upper jaws.
• Made from Keratin, and have overlapping
hair-like bristles.
• Filter feed by taking a large mouthful of
H2O and forcing it out through the baleen.
• The whale then licks the trapped food off
the bristles.
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Filtering apparatus in a baleen
whale (Suborder Mysticeti)
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Baleen Whales- Cont’d
• They are the largest of all whales, and the
largest animals ever to live on earth.
• Blue whales- average 80 ft long, 90-140
tons. (Record is 110ft, and 200 tons!)
• Rorquals- baleen whales that have an
expanding lower throat to feed on schools
of krill. Ex- Blue, fin, minke, and
humpback whales.
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Baleen Whales- Cont’d
• Right whales and bowhead whales- Have
fine bristles that can catch copepods as
well as krill.
• Grey whales- bottom feeders, eat squid
and amphipods.
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Blue whale- a rorqual
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Humpback whale
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Grey whale
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Minke Whale
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Right whale
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Bowhead Whale
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Toothed Whales- Suborder
Odontoceti
• Orcas, dolphins, porpoises.
• Teeth are used for catching prey, not
chewing.
• Food is swallowed whole, then ground up
in a three chambered stomach.
• Sperm whale- the largest toothed whale,
feed on squid, and are the deepest diving
whales.
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Toothed Whales- cont’d
• Orcas- killer whales that feed on seals and
sea lions.
• Dolphins and porpoises- smallest of
toothed whales.
• *Porpoises are smaller and have blunt
noses.
• They often travel in groups called pods.
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Orcinus orca
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Tursiops truncatus
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Phocoena phocoena- harbor porpoise
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Harbor porpoise
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Biology of Marine Mammals
• Difficult to observe- many do not survive
well in captivity.
• Swimming- streamlined body- up and
down motion of tail and flukes.
• Fastest speed recorded- 40mph in
common dolphins!
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Common dolphins
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Up and down swimming motion of
cetaceans
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Breathing- the trick to cetacean
survival
• Blowhole- on top of the head.
• Cetaceans breathe very quickly to avoid drawing
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in water.
Fin whales can exhale and inhale 3000 times
as much air as we can in only 2 seconds!!!
Condensation of water vapor in the breath and
seawater creates a distinctive spout.
this plus diving patterns can help identify
whales from a distance.
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More on diving
• Cetaceans have blubber to prevent heat
loss.
• Mouths exposed to cold - network of
blood vessels in the tongue helps prevent
heat loss though the mouth.
• Most marine mammals make very long
dives.
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Dive times
• Sea otters- 4-5 minutes- not too deep.
• Pinnipeds- usually up to 30 minutes.
• Weddell seal- can dive for over 1 hour!
• Cetaceans- dive for ~ one hour.
• baleen whales- feed on plankton•
shallow divers.
toothed whales- dolphin dive up to
990ft, sperm whales up to 7380!!!!
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How do they do it?- Several crucial
adaptations!
• 90% gas exchange- compared to 20% in
humans.
• They have more blood than non-diving
mammals.
• Blood has a higher concentration of Red
blood cells, which have more hemoglobin
than land mammals.
• Muscles have more myoglobin- their
muscles can store oxygen.
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Marine mammals can reduce
oxygen consumption.
• They can slow their heart rate when they
dive.
• They can reduce blood flow to nonessential parts of the body.
• Nitrogen- their lungs collapse when they
dive, which prevents excess nitrogen from
dissolving into the blood. (which causes
the ‘bends’)
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Echolocation- natures sonar
• Used to find prey and orient themselves in
their surroundings.
• They emit sounds waves, and interpret the
sounds reflected back from objects.
• The time for echo return tells them
distance.
• Very precise- dolphins can distinguish
between very similar objects.
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Echolocation (cont’d)
• Clicks and whistles produced by air sacs in
the head.
• Melon- fatty structure on the head of
toothed whales- believed to be involved
with focusing and directing sounds.
• Echoes are picked up by the lower jaw,
transmitted to inner ears and then the
brain.
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Biology of echolocation
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The
melon
gives this
beluga
whale its
rounded
forehead.
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Communication
• Very prominent in social groups of
pinnipeds.
• In cetaceans- very complex sounds
indicate mood, mating signals, and can
identify a species.
• Humpback whales- sing a very distinct
song during mating season- can repeat
the same song for days.
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Behaviors
• Play behavior- many cetaceans play with
food or floating objects.
• Breaching- leaping into the air, and loudly
crashing on the surface.
• Why?- perhaps to attract mates,
remove parasites, scan the shoreline.
• Spying behavior- lifting their heads out of
the water to view the surface.
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Some
whales will
surround
and protect
an injured
member of
their pod.
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Spying behavior in orcas
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Pilot Whale “Spying”
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Grey Whale ‘Spy hopping’
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Dolphins helping an injured companion to
the surface to breathe.
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Beaching
• No one is quite sure why cetaceans beach
themselves.
• Could be following an injured or sick pod
member.
• Could be linked to high-intensity sonar
used by military.
• Caused hemorrhages in inner ears, and
rapid surfacing causes the bends.
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56 Pilot whales beached on Cape
Cod, 2002
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Migration
• Many great whales migrate thousands of
miles to mate or to feed.
• Baleen whales- feed at the poles during
the summer, migrate to warmer waters in
winter to breed.
• Spying behavior very common in migrating
whales.
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Figure 9.31
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Reproduction in pinnipeds
• Pinnipeds- male seals usually mate with
only one female.
• Elephant seals and sea lions- breed in
harems, with one dominant male
defending his female group.
• Delayed implantation- embryo goes
dormant in order for the timing of the
pups to coincide with the migration to
breeding grounds.
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Stellar sea lions and California sea
lions at their breeding grounds
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Mother and pup
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Reproduction in cetaceans
• Gestation is usually 11-12 months, to
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coincide with migration patterns.
It takes- 9 months to develop a 7lb human.
11 months to develop a 3 ton blue
whale calf!
Cetaceans are born tail first to allow
extended time to receive oxygen from the
placenta.
Blue whale calves can gain 200 lbs and grow
1.5inches a day for the first 7 months!
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Figure 9.35
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Table 9.02
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Table 9.01
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