Marine Reptile Characteristics Land vertebrates are called
tetrapods because they have four limbs designed for locomotion on
land. They have lungs and breathe air, and, except for amphibians,
they have reproductive systems that are not tied to water. Marine
reptiles have scales to minimize water loss, their eggs have a
leathery shell to prevent them from drying out, and they are
poikilotherms and ectotherms. There are about 7000 species of
reptiles.
Slide 3
Marine Reptile Characteristics Poikilotherms are organisms that
have a body temperature that varies with that of the environment.
Ectotherms are organisms that lose metabolic heat to the
environment without it affecting their body temperatures. Organisms
that are poikilotherms and ectotherms commonly are called
cold-blooded.
Slide 4
Sea Turtles Sea turtles have an armor-like shell or carapace
that is fused to their backbone. Unlike land turtles, sea turtles
cannot retract their legs into their shells. Their legs are
modified into flippers for swimming. There are only seven species
of sea turtles in the world: the green turtles, the hawksbill
turtle, the leatherback, the Ridleys, and the loggerhead.
Slide 5
Sea Turtle Reproduction All female sea turtles return to land
to lay their eggs. Many migrate very long distances (up to 1360
miles) to return to the beach where they were born. They probably
do not breed every year. They lay 100 to 200 eggs in a nest that
they excavate in soft sand. The eggs hatch after 2 or so months and
the baby sea turtles immediately crawl to the water and swim away.
Not much is known about what happens to the babies as they mature
into adults. Mortality is very high.
Slide 6
Sea Turtle Endangerment Sea turtle beaches have been developed
as beaches, condos, and hotels, and the artificial lights that come
with people are detrimental to both the females and the babies.
Dogs, ghost crabs, raccoons, wild pigs, and people eat sea turtle
eggs. The babies are easy prey for predators, both on land and in
the water. Adult sea turtles are accidentally caught in fishing
nets and drown. Ocean predators, including people, also eat
them.
Slide 7
Marine Snakes There are about 55 species of sea snakes and they
are found in the tropical Indian and Pacific oceans. Their tails
are paddle-shaped for swimming. They are completely marine; they
mate in the ocean and give birth to live young. They are carnivores
that are closely related to cobras, and they are venomous.
Slide 8
Marine Iguanas Marine iguanas only occur on the Galapagos
Islands, in the equatorial Pacific just off the coast of South
America. These unique reptiles spend part of their time on land,
resting, mating, and sunbathing. They live on rocky coastlines and
feed in the coastal ocean, eating sea weeds. BBC Video
Slide 9
Salt Water Crocs Salt-water crocodiles live in mangrove swamps
and estuaries in the eastern Indian Ocean, Australia, and some of
the western Pacific islands. They are mostly coastal. They are very
aggressive and will attack people. BBC Video Saltwater Croc vs.
Great White
Slide 10
Marine Birds Birds are homeotherms and endotherms, which allows
them to live in a wide variety of habitats. Birds can fly, and
their bodies are covered with waterproof feathers that also help
insulate them. Birds have hollow, light bones that help them fly.
The shells that cover bird eggs are harder and more resistant to
water loss than are reptile eggs.
Slide 11
Homeotherms are organisms able to keep their body temperature
more or less constant regardless of the temperature of the
environment. Endotherms are organisms that retain some metabolic
heat, which raises their body temperature.
Slide 12
Sea Bird Characteristics Seabirds are birds that spend a
significant part of their lives at sea and feed on marine
organisms. Seabirds nest on land. Most breed in large colonies,
mate as lifelong pairs, and take care of their young. Seabirds are
related to several different groups of land birds, and they differ
from each other with respect to their flying skills, feeding
mechanisms, and ability to live away from land. Most are predators
on fish, squid, and bottom invertebrates. They are found from pole
to pole.
Slide 13
Types of Sea Birds The five types of seabirds are the penguins,
the tubenoses, the pelicans (and related birds), the gulls (and
related birds), and the shore birds.
Slide 14
PENGUINS! Penguins are flightless and their wings are modified
to be flippers that help them fly underwater. They have dense
bones, which reduce buoyancy and help them remain underwater.
Penguins are very good swimmers, but are very clumsy on land. They
generally are adapted for cold weather (both on land and in the
water) and prey on fishes. Penguins are found only in the Southern
Hemisphere or at the equator.
Slide 15
A penguin Dilemma 2 volunteers are needed to voice the two
penguins in the following video A Penguin Dilemma Serious BBC
Video
Slide 16
Tubenose Birds The tubenoses are a group of seabirds with
tube-like nostrils and heavy beaks that usually curve at the beak.
They have salt glands that help them get rid of excess salt. The
salt glands empty into the nostrils, and as a result these birds
often look like they have runny noses. Tubenoses include the
albatross, the shearwaters, and the petrels. They are skillful and
strong flyers and fishers that spend months at sea without landing.
Their flights may take them thousands of miles at a stretch. They
only return to land for reproduction.
Slide 17
Examples of Tubenoses Albatross Mating Dance Shearwater
Behavior
Slide 18
Mammal Characteristics Marine mammals are in the Class
Mammalia, and, like birds, are endotherms and homeotherms. They
have hair, give birth to live young, and nurse their young.
Pregnant females nourish their unborn babies through a placenta, a
membrane that connects the embryo to the womb. Like other mammals,
marine mammals have large brains relative to their body sizes.
Additionally, like other mammals but unlike fishes, they breathe
air.
Slide 19
Groups of Marine Mammals The four groups of marine mammals are
the 1) seals, sea lions, and walruses; 2) sea otters and polar
bears; 3) manatees and dugongs, and 4) whales, dolphins, and
porpoises. Seals, sea lions, and walruses are in the Order
Pinnipedia, which are closely related to the Order Carnivora, with
its cats, dogs, bears, and their kin. Sea otters and polar bears
are in the Order Carnivora. Manatees and dugongs are in the Order
Sirenia and are closely related to elephants and their relatives.
Whales, dolphins, and porpoises are in the Order Cetacea and are
distantly related to animals such as cattle, sheep, pigs, and
hippos.
Slide 20
Pinnipedia The Order Pinnipedia includes the seals, sea lions,
and walruses. They are streamlined and have paddle- shaped flippers
for swimming. They rest and breed on land. Pinnipeds are predators
that eat mostly fishes and squid and mostly live in cold water.
They have a thick layer of fat called blubber just under their skin
that helps keep them warm, serves as a food reserve, and aids in
buoyancy. Pinnipeds also have bristly, thick hair to help keep them
warm.
Slide 21
Seals Seals are pinnipeds with rear flippers that do not move
forward well and which do not rotate backwardsthis limits their
mobility while on land. In the sea, they swim with powerful strokes
of their rear flippers. On land, they pull themselves forward using
their front flippers. There are 19 species of seals.
Slide 22
Conservation Seals have been hunted for their blubber, skin,
and meat for centuries and longer. Overhunting in the 20th century
led to precipitous declines in some seal populationsmany species
are endangered or threatened. The Marine Mammal Protection Act of
1972 protects all marine mammals, including seals, and restricts
the sale of all products in the United States.
Slide 23
Sea Lions Sea lions are pinnipeds that are similar to seals in
terms of their distribution and life styles. Sea lions include the
fur seals (which arent really seals!), and there are 14 species.
They have the following characteristics: they have external ears,
they can rotate their rear flippers forward and backwards (which
means they can move around on all four limbs on land), and their
front flippers can rotate forward and backwards (allowing them to
prop themselves up on land). Sea lions exhibit sexual dimorphismthe
males are much larger than the females.
Slide 24
Sea Lion Conservation Sea lions have been hunted for their
blubber, skin, and meat for centuries and longer. Overhunting in
the 20th century led to precipitous declines in some sea lion
populationsmany species are endangered or threatened. The Marine
Mammal Protection Act of 1972 protects all marine mammals,
including sea lions, and restricts the sale of all products in the
United States.
Slide 25
Walruses The walrus is a large pinniped with a pair of large
tusks that protrude downwards from the mouth and that are used for
defense. Unlike the other Pinnipeds, it feeds mostly on
bottom-dwelling marine invertebrates.
Slide 26
Sea Otters Sea otters are the smallest marine mammals and,
unlike other marine mammals, lack a layer of blubber. Instead, sea
otters have dense fur that traps air as insulation. Sea otters
spend all of their time in the water; they live, breed, feed, etc.
there. They feed on many different types of invertebrates,
including sea urchins, abalone, mussels, and crabs.
Slide 27
Sea Otter Conservation Sea otters were hunted to near
extinction because of their thick, soft fur. International
protection in 1911 helped re-establish the severely decimated
populations. However, recently, populations are again in decline,
due most likely to changes in their ecosystem due to pollution and
overfishing. Sea otters are a threatened species.
Slide 28
Polar Bears Polar bears are semi-aquatic marine mammals that
spend a lot of time on drifting ice in the Arctic. They are
carnivores, feeding mostly on seals. Their populations have been
declining due to habitat loss warmer climates near the poles is
melting the ice upon which they depend.
Slide 29
Sirenia The Order Sirenia includes the manatees and the dugong.
They are the only vegetarians among the marine mammals and feed on
sea grasses and submerged vegetation. They have a pair of front
flippers but instead of rear flippers, they have a paddle-shaped
horizontal tail. Manatees live in the Atlantic Ocean in tropical
and subtropical waters. The dugong lives on the east coast of
Africa to some of the Pacific islands
Slide 30
Sirenia People hunted sirenians for food, skin, and their oil-
rich blubber. Because they reproduce slowly and because their
habitat (the coastal ocean) has been altered and destroyed by human
development, sirenians are in danger of extinction. Several species
are already extinct; the four remaining species are all
endangered.
Slide 31
Cetaceans (whales) The largest group of marine mammals is the
Order Cetacea, which includes the whales, dolphins, and porpoise.
Of all the marine mammals, the cetaceans are most fully adapted to
an aquatic life style. They spend their entire lives in the water,
have very stream- lined bodies, and superficially resemble
fish.
Slide 32
Why do these mammals look like fish? Convergent evolution
describes different, usually very un-related species that have
similar structures because they have similar life styles. Cetaceans
are mammals; fish are fishdefinitely not closely related. They
superficially resemble one anotherstream- lined bodies, pectoral
fins/flippers, dorsal fins, etc. because their bodies are well
adapted to swimming and life in the ocean.
Slide 33
Cetaceans have a pair of front flippers. The muscular tail ends
in a pair of fin-like, horizontal flukes. There is a dorsal fin,
towards the end of the body. The nostrils are on top of the head
and form a single or double holed opening called the blowhole. The
blowhole is using for both inhaling and exhaling when the animal is
at the surface. Cetacean Anatomy
Slide 34
Groups of Cetaceans The two groups are the toothless,
filter-feeding whales and the toothed, carnivorous whales (which
includes the dolphins and porpoises).
Slide 35
Baleen Whales The toothless whales are also known as the baleen
whales. There are 13 species of baleen whales, and they are among
the largest animals that have ever lived on earth. They were once
common in the oceans, but hunting for their meat and blubber has
decimated many of their populations. Baleen whales have two
blowholes (compared to the toothed whales, which only have one
blowhole).
Slide 36
Baleen Whales The baleen whales have rows of flexible, fibrous
plates called baleen that hang from their upper jaws. The inner
edge of each baleen plate is made up of hair-like bristles that
form a dense mat on the roof of the mouth. The baleen plates are
made up of keratin, the same material that makes up our fingernails
and hair. The baleen whales filter feed by gulping mouthfuls of
water and then squeezing the water out through the bristles. Any
food that is left behind sticks to the bristles and the whale licks
it off with is tongue and then swallows it.
Slide 37
Toothed Whales There are approximately 80 species of toothed
whales. Their teeth are adapted to catch fish, squid, and other
preythey dont chew their prey; they swallow it whole. The toothed
whales have a single blowhole opening, unlike the baleen whales,
which have two blowholes. The toothed whales include the dolphins,
porpoises, and the non-baleen whales.
Slide 38
Adaptations for diving A feature that helps the cetaceans swim
and dive more effectively is having the blowhole on top of the
head, which helps them to inhale and exhale very efficiently and
quickly at the surface. To help them remain underwater for long
periods of time without running out of oxygen for respiration,
marine mammals breathe very efficiently and are able to put large
amounts of oxygen into their bloodstreams. They have more blood
cells that carry oxygen and have more muscle cells that store
oxygen. Marine mammals are able to reduce their oxygen consumption
while diving. They typically reduce their metabolism and heart
rates and reduce blood flow to their extremities (while maintaining
blood flow to essential organs like the brain).
Slide 39
Echolocation Echolocation is a sensory system based on hearing
that most toothed whales (dolphins and porpoises) and some
pinnipeds and baleen whales use to find prey and to orient to their
surrounding.
Slide 40
Echolocation Cetaceans echolocate by emitting a series of
clicks, squeaks, and whistles as air is forced through passages in
the head while the blowhole is closed. These noises are focused and
directed outward by the melon, a fatty structure on the forehead
(the melon gives toothed whales their characteristic rounded
foreheads). The echo of the noises (which bounce off objects around
the cetacean) is received primarily by the lower jaw, which
transmits the echoes to the two very sensitive inner ears. The
echoes are interpreted by the brain, which forms a mental picture
of the surroundings.
Slide 41
Communication Vocalizations are the sounds that animals make to
communicate with each other (echolocation is NOT a type of
vocalization). Sea lions and fur seals bark and whimper; seals
grunt, whistle, and chirp. Cetaceans use low-frequency sounds such
as grunts, barks, squeaks, chirps, and even moos to communicate
with each other. Perhaps the most well known cetacean vocalization
is the song of the humpback whale, which may last for 1/2 hour or
longer.
Slide 42
Communication Marine mammals vocalize for many reasons.
Pinnipeds vocalizations are especially important in maintaining
territories and in recognition between mother and pup. Cetaceans
vocalize during social and sexual encounters. Vocalization allows
individuals to identify one another and communicate information
about food sources, predators, and alarm. Male humpback whales sing
to attract females and to advertise their readiness to mate.