Chapter 9
Marine Reptiles, Mammals, and
Seabirds
Characteristics of Marine Reptiles
- Skin covered by _____
- Feet clawed or legs lacking or reduced
- Poikilotherms with ____thermic metabolism
Four types of marine reptiles exist today:
1. Sea Turtles
2. Sea Snakes
3. Marine Iguana
4. Saltwater Crocodile
Sea Turtles
• All species of sea turtles are threatened or
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endangered
Endangered (E) means that a species is under
direct threat of species survival (extinction is a
definite threat)
Threatened (T) means that the species may
become endangered
Both designations give these species protection
under the Endangered Species Act
Sea Turtles
• Seven or eight species of sea turtles exist today:
1. Leatherback sea turtle (E, feed often on jellyfish but
can dive to deep depths to feed on other prey items
2. Loggerhead (T, feeds inverts. such as crabs and
molluscs)
3. Hawksbill sea turtle (E, feeds mainly on corals,
sponges and associated invertebrates
4. Olive ridley sea turtle (E, feeds inverts. such as
crabs and molluscs)
Sea Turtles
5. Kemps ridley sea turtle (critically E as only one
nesting site in Rancho Nuevo, Mexico and feeds
inverts. such as crabs and molluscs) Releasing them
now in TX at Padre Island National Seashore
http://www.youtube.com/watch?v=W4u3GL9SyyM
6. Australian flatback sea turtle (E, feeds mainly
seagrass and associated invertebrates such as shrimp
and jellyfish)
7. Green sea turtle – some biologists recognize two
species of green turtles, the Pacific green turtle and the
Atlantic green turtle (this is the reason for the 7 or 8
species discrepancy; E but numbers increasing, feeds
seagrass and algae and has greenish fat deposits)
Sea Turtles
• Structurally, sea turtles have an upper shell
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known as the carapace and a lower shell known
as the plastron
The ribs are expanded in size and fused to their
shell
All sea turtles have powerful jaws, but no teeth
Like other reptiles, sea turtles are poikilothermic
and _____thermic.
Sea Turtles
• Sea turtles breed at sea
• Internal fertilization occurs – males use their
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long tails as well as the claws on the front
flippers to “grip” the female during reproduction
Females can store sperm
One clutch (group) of eggs can have multiple
paternity – males and females are not
monogamous
Sea Turtles
• Females normally breed every 2-4 years
• These females must return to land to deposit
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their eggs near the dune line (above the high tide)
Females dig a hole in the sand using only the
back flippers
Each clutch of eggs normally has an average of 120
eggs, although large variations in these numbers
have been recorded
Sea Turtles
• The eggs have a typical incubation period of
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around 60 days – although this varies according
to air temperature (a range of 45-75 days is not
unusual)
The eggs are very leathery at the time the
mother lays the eggs
As they incubate, they become more
brittle, making it easier for the hatchlings
to escape the egg
Sea Turtles
• Sea turtles, like many reptiles, exhibit
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temperature dependent sex determination
This means that the gender of the hatchling is
not genetically predetermined
Gender is determined by the temperature of the
environment in which the egg was incubated
For each species, there is a “pivotal”
temperature that will generate 50% males and
50% females; temperatures higher than pivotal
will produce more females, temperatures lower
than pivotal will produce more males
Chordate
Reptile
Sea Turtle
Sea Snakes
• There are 55 species of sea snakes
• These snakes are found only in the
Indian and Pacific Ocean
• These snakes have a laterally flattened
body with a paddle-like tail for
propulsion through the water
• Most species are 3-4 feet in length as
adults
Sea Snakes
• Sea snakes mostly breed at sea and
most species are ovoviviparous
• A few species still return to land to lay eggs
• Bites from sea snakes can be fatal for
humans– the sea snakes are related to the
cobra and have a powerful venom
• Fortunately, sea snakes are not known to
be aggressive
• Sea snakes are carnivorous and mainly
feed on fish
Saltwater Crocodile
• This species is found in Australia, the Indian Ocean and
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some Western Pacific Islands
It can be found in estuaries, mangrove swamps, rivers
and the open ocean
It is a predatory species that eats all types of prey items
including humans
The saltwater crocodile is a large species reaching
lengths of over 30 feet (although individuals over 20 feet
are rare)
This species is not secretive like the American Crocodile,
but is an aggressive hunter
Marine Iguanas
• Marine iguanas live on the Galapagos
Islands
• While they are called marine, they only
spend a portion of their time in the
water
• They dive to feed on seaweed near the
shore
• A large portion of their day is spent
basking on the shore to warm up from
their dives in the cold water surrounding
the Galapagos
Characteristics of Seabirds
• Homeotherms able to maintain a constant
body temperature derived through
metabolic means = ____
• The ____ that cover the body are coated
with an oil from glandular secretions
• This oil helps to waterproof the body
• The hard shelled egg provides more
protection than the leathery shell of
reptiles
Seabirds
• Many species of seabirds are colonial nesters
- they nest in large colonies of individuals
near the shore – some on cliffs, others in low
shrubs or trees, others directly on the
ground—Called rookeries
• Some species are monogamous and mate for
life and in some both sexes care for chicks
• Birds are well known for their protection of
young and other behaviors such as preening
and complex rituals for selecting a mate
Seabirds
• Penguins are flightless with the wing modified
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into a flipper-like structure
Penguins spend a great deal of time in the marine
environment searching for prey of fish, squid, and
krill (shrimp-like crustaceans common at poles)
Most species of penguins live mainly in Antarctica
They have a layer of fat and trap air in the
feathers to help them survive these cold
environments
Males share in
feeding chicks
Seabirds-Tubenoses
• Tubenoses-tube-like nostrils and
heavy curved beaks
• Albatrosses are white and black and
glide on extremely long and narrow wings
(up to 11 ft.) needed to support this
largest of seabirds that feed mostly on fish
• rarely seen from shore
• Nest in large colonies on remote oceanic
islands
• Yellow nosed albatross is rare in Texas
and is usually found in Northern Canada
Yellow nosed albatross
Large, white and black seabirds with long narrow wings. Nest on remote oceanic islands.
Seabirds-Tubenoses
• Shearwaters are gull-sized, greyish-black
and white birds that skim the waves in
search of fish (pursuit plunging)
• rarely seen from shore
• Nest in colonies on small, isolated islands
or under clumps of dense vegetation
• Five species in Texas with two being rare
and three relatively common to the state
Greater shearwater
Gull-sized, greyish black and white birds that nest in colonies on small, isolated islands
or under clumps of dense vegetation
Seabirds-Tubenoses
• Petrels feed in flight snapping up fish
from surface and storm petrels hover over
waves to pluck up prey and may follow
ships or whales
• Spend a great deal of time in the marine
environment searching for prey but
sometimes are seen near the shore
• Wilson’s storm petrel nests in colonies on
islands and has sooty brown plumage
• Five species known from Texas with four
rare and Wilson’s storm petrel common
Wilson’s storm petrel
nests in colonies on islands and has sooty brown
plumage.
Seabirds
Pelican and Related Birds nest in large
colonies near shore
• Pelicans have massive bills and throat
pouches used as dip nets as they plunge
into the surface of water to catch fish
• Spend much time at sea searching for
prey but often are seen near shore
• American whites nest on ground and
brown pelicans in trees; both are in Texas
American white pelican
American whites nest on ground and brown pelicans in trees.
Both have large beaks and throat pouches
Seabirds- Pelicans and Related Birds
• Frigatebirds soar over sea and have
aerial pursuits as they skim waves for fish;
also may attack other seabirds causing
them to drop their food so they can get it
• Spend a great deal of time at sea but also
near shore
• Nest in colonies in treetops or in high cliffs
• Magnificent frigatebird, which occurs in
Texas has large wings, forked tail, and is
black with an orange throat
Magnificent frigatebird, which occurs in Texas has large wings, forked tail,
and is black with an orange throat. May attack other seabirds and steals fish.
Seabirds- Pelicans and Related Birds
• Boobies have narrow wings and are
sudden, surface plungers diving from
great heights into the sea to grab fish
• Spend time in marine environment to
search for prey but often are near shore
• Nest in colonies on small islands
• Four species occur in Texas with brown
(brown and white) and masked (white
with black around eyes) common
• blue- and red-footed are rare
Masked booby and chick at nest in an island
colony. Feed by plunging after fish from great
heights.
Seabirds- Pelicans and Related Birds
• Cormorants are long-necked and dark
colored in two Texas species with a
hooked bill and a throat pouch; dive and
pursue fish underwater
• Spend a great deal of time in the marine
environment searching for prey but often
are seen near shore in freshwater habitats
• Nest in colonies in trees, flat ground, and
cliffs
• Two species occur in Texas
Cormorants are long-necked and dark colored and nest in colonies
on ground, in trees , and on cliffs. Use their curved beak and
throat pouch to pursue fish underwater.
Gulls and Related Birds
• Gulls comprise a large number of seabird
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species often seen near shore
Gulls dip down to capture fish and invertebrates
but also are persistent scavengers along shore
Terns are graceful fliers that plunge dive and
use their straight narrow beak to swallow fish
whole. Most with forked tail.
Both nest in large colonies and gulls often nest
near other rookeries and eat eggs and young of
other seabirds.
Royal terns dive and use large
bill to catch small fish whole.
Forked tail is cut off in this
picture.
Seabirds
• Other species of birds classified as wading
and shorebirds are associated with the sea
• However, none of these birds are adapted to
the marine environment in the same way
that previously discussed ones are
• Even those that spend relatively long periods
of time at sea still have features very much
like terrestrial birds
Characteristics of Mammals
-Skin possesses ____
• Homeotherms with _____thermic
metabolism
• Mostly viviparous with placenta
• Mammary and other glands
• Larger brain in relation to body size
• Many sexually dimorphic (males and
females look different in size, coloration,
features, etc)
Major Groups of Marine Mammals
1. Pinnipedia “flipper foot” – seals, sea
lions and walrus
2. Carnivora – sea otter and polar bear
3. Sirenia (In Greek myths, sirens were
dangerous sea creatures that lured
sailors into water (+mermaid))– dugong
and manatees
4. Cetacea “whale”– whales, dolphins and
porpoises
Order Pinnipedia
• Below is a comparison of sea lions/fur seals versus true seals.
• Notice the external ear of sea lions/fur seals (not present in
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seals).
Also notice that sea lions/fur seals can rotate posterior flippers
forward for more efficient locomotion on land.
Order Pinnipedia
Seals:
• Most live in cool or cold water
• Monk seals are the exception – they live in warmer
waters
• Hawaiian and Mediterranean monk seals are endangered
• Caribbean monk seals have not been seen since the
1950’s and likely are extinct
Order Pinnipedia
- Seals have no external____, posterior flippers cannot
rotate forward so lays flat
• SIZE: About 4-19 ft.; males are approximately the same
size as females; weight ranges from 110-11,023 lb
• DIET: Eat various fish, shell fish and cephalopods
• RANGE: Coastlines and ice fronts throughout the world
except the Indian Ocean. Some species are found in inland
lakes.
• HABITAT: Prefer coastal areas with shallow waters near
abundant food sources.
Order Pinnipedia
SEA LIONS/FUR SEALS have external ear; rear flippers
rotate forward so can set up
• SIZE: Range in size from about 4-10.8 ft.; males are much
larger than females; weight ranges from 47-2,205 lb
• DIET: Same as seals
• RANGE: Widespread except for Europe; Coast of
northeastern Asia, western North America, South America,
southern Africa, southern Australia, New Zealand and many
southern islands
• HABITAT: Same as seals
Order Pinnipedia
Walruses are very distinctive having a large, robust,
fusiform body that is usually reddish-brown in color.
On their head region, walruses lack external ear
flaps like seals, have hundreds of short whiskers,
and both males and females possess large tusks.
Like other pinnipeds, the fore and hind limbs of a
walrus are modified into flippers. On land, walruses
are capable of rotating their hind flippers under
their pelvic girdle to walk on all fours in a
similar manner to sea lions. Adult males are
slightly larger than females with longer and
stouter tusks.
Order Pinnipedia
WALRUSES:
• SIZE: The Pacific subspecies is larger than the Atlantic.
Newborn calves are about 3-4 ft. long. MALE 9-12 ft.
FEMALE 7.5 to 10 ft. Males usually larger. Weight
ranges from about 100-3000 lb.
• DIET: Mainly bivalves such as clams; also other
benthic invertebrates such as marine worms,
snails, sea cucumbers, squids, and crabs.
Occasionally prey upon fish and scavenge on seal
carcasses. There are rare cases of very large, male
walruses that habitually prey upon seals.
• RANGE: Arctic Sea - both Pacific and Atlantic (Bering,
Laptev and Chukchi seas)
• HABITAT: In relatively shallow water (generally not
more than 260 ft. deep). Hauls out on ice floes, pack
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ice and small rocky islands when ice is not present.
Below is a illustration of a walrus.
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Order Carnivora
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Sea otters possess fine, dense fur coats. Their forefeet are
small and dexterous with retractile claws and the
flipper-like hind feet are broad and webbed; mature
male sea otters tend to be slightly larger than
females.
SIZE: Alaskan sea otters are slightly larger than California
sea otters. Male Alaskan sea otters reach lengths up to 58
in. and male California sea otters average 4 ft. Female
Alaskan sea otters measure up to 55 in. in length; weight
ranges from 44-85 lb.
DIET: A sea otter has a metabolic rate much higher
than most mammals of similar size, and must consume
large quantities of food. Adult sea otters may eat as much
as 20 lb. of food each day. Among their food preferences
are sea urchins, crabs, bivalves, octopus, and fishes.
Order Carnivora
Sea otters
• RANGE: In coastal regions throughout the
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eastern North Pacific Ocean.
HABITAT: Typically found in coastal water
near (no further than 0.6 mi.) shore.
Keystone species of kelp forest.
Order Carnivora
Polar bears are the largest land carnivore. They have thick
white fur and have black skin color on the nose, eyes, lips
and footpads. Polar bears have smaller ears and longer
necks than other bears. Adult male polar bears, called
boars, are substantially larger than adult females.
• SIZE: At birth, cubs are about 12 in. long; Males typically 8.2-9.8 ft.
long; Females typically 6.6-8.2 ft. long. Newborn cubs weigh about
16-24 oz.; Males (larger than females) weigh 772-1,433 lb.;
Females weigh 331-551 lb.
• DIET: Adult polar bears need an average of 4.4 lb. of fat per day to
maintain their weight. Their diet includes mostly ringed and bearded
seals and also includes other seal species, walruses, narwhals,
beluga whales, whale carcasses, fish, reindeer, birds, eggs,
berries and kelp.
Order Carnivora
Polar bears
• RANGE: Circumpolar arctic
• HABITAT: Inhabit Arctic sea ice, water, islands, and
continental coastlines
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Order Sirenia
• Amazonian manatee is the smallest of the manatees.
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Several physical characteristics distinguish it from the other
two species. It lacks nails on its pectoral fins, and usually
has whitish patches on its underside.
West Indian manatee is distinguished by differences in
cranial measurements and by their geographic distribution.
It is one found in USA.
West African manatee is similar to the West Indian
manatee, but it differs in some important respects such as
position of the eyes, snout, and cranial bones.
All manatee's bodies are streamlined - full around
the middle and narrowing to a paddle-shaped tail.
The true color of a manatee is gray, although it may
appear brownish gray.
Order Sirenia
MANATEES:
• SIZE: Adult West Indian and West African
manatees average 10 ft. in length; Average adult
weighs approximately 800-1,200 lb. Females are
generally larger than males.
• DIET: Manatees are primarily herbivores.
They feed on a wide variety of submerged,
emergent, floating, and shoreline vegetation.
Manatees have occasionally been seen to eat
foods other than plants such as fish and clams.
Order Sirenia
MANATEES:
• RANGE: All living manatee species are found in warm tropical
and subtropical waters. Amazonian manatees are the only
species of manatee confined to fresh water. They inhabit the
Amazon Basin, mostly in Brazil.
• HABITAT: The West Indian and West African manatees inhabit
rivers, bays, canals, estuaries, and coastal areas rich in
seagrass and other vegetation. They can live in fresh, saline
(salt), and brackish waters. The Amazonian manatee is restricted
to fresh water. They are most common in floodplain lakes and
channels in white-water river systems.
Illustration of a typical manatee.
Order Cetacea
• This order includes toothless filter-feeding
whales and toothed whales including
dolphins (one seen often in TX; conical
teeth) and porpoises (flat teeth).
• Fore limbs are modified into flippers.
• Fin-like tail is known as a fluke.
• Nostrils are located on the top of the head
as a single or double opening known as a
blowhole.
Order Cetacea
• Within the cetacea, two suborders exist, toothed
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whales (Odontocetes) and baleen (flexible plates
that hang from upper jaw) whales (Mysticetes).
Visually, the two suborders can be easily
distinguished by the presence of teeth and
a single-nostriled blowhole (toothed) or
baleen with a two-nostriled blowhole.
SIZE: In general, baleen whales are much
larger than toothed whales, ranging in
length from about 21-85 ft. Most toothed
whales are less than 20 ft. long.
Baleen whales have rows of flexible, fibrous plates known as baleen
that hang from the upper jaws and a two-nostriled blowhole.
Order Cetacea
• Baleen whales are filter feeders. They
take in huge mouthfuls of water containing
small fishes or invertebrates. The baleen
traps the prey, and water is forced back
out of the mouth.
• Baleen whales are represented by 13
species, including the right whale, gray
whale, blue whale, and humpback
whale.
Examples of Baleen Whales
Order Cetacea
• Toothed whales are named for their peg-like
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teeth, which vary considerably in number and
size among the species. Teeth are adapted for
grasping and tearing, rather than chewing.
Toothed whales include dolphins (common in
TX), narwhals, sperm whales (largest
toothed), and killer whales.
found in coastal waters, rivers (5 species of
dolphins) or in the pelagic environment.
Examples of Toothed Whales
Adaptations for Diving:
• Rapid breathing prior to dive
• Lungs remove 90% of O2 from air (as
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opposed to 20% for humans)
Elastic tissue in lungs helps them expand
the lungs temporarily
Marine mammals have more blood than
non-diving mammals for their size (means
more hemoglobin to carry oxygen)
Muscles contain more myoglobin to hold
oxygen in tissues
The heart rate slows dramatically during a
dive
Blood flow is reduced to extremities and
digestive system
Muscles employ anaerobic respiration as
necessary (results in lactic acid build-up)
Marine mammals can tolerate more lactic
acid than other mammals
Rib cage and lungs collapse during dive to
force air into tissues and prevent
decompression sickness
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Echolocation
• Sound waves are emitted as a
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series of clicks of varying
frequencies
Melon directs the outgoing
sound waves
After the echo strikes an
object, it is reflected back
These reflected echoes are
received back by the melon
and lower jaw
The longer it takes a echo to
return, the farther away the
object is located
Marine Mammal Behaviors
• Marine mammals as well known for their
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vocalizations such as the “barking” of sea lions
and songs of the humpback whale.
Marine mammals engage in play activities
regularly including sexual play.
Marine Mammal Behaviors
• Many species are known
to jump out of the water
and crash back into the
water on their backs. This
is known as breaching.
• May be removing
parasites, a warning
signal, to avoid suitors, or
to have fun!
• Sometimes hold their
bodies out of the water.
This behavior is known as
“spyhopping.”
• Humpback whale
Marine Mammal Behaviors
• Many marine mammals are known for their long
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migrations.
The longest migration is that of the gray whale;
this migration is over 11,000 miles!!
Notable Migrations
Marine Mammal Behaviors
Care giving and Strandings or beaching :
• When one member of a group (pod) of animals is
sick/injured, other members will care for it. Mass
strandings are often the result of caregivers following a
sick/injured animal to shore.
• As an example, 55 pilot whales mass stranded on a
beach in Cape Cod, MA. Volunteers desperately tried to
protect the animals from the summer heat with sheets
and water, but unfortunately the elements proved too
extreme for the whales and only two survived.
Reproduction in Marine Mammals
• Fertilization is internal via copulation
• Copulation occurs on land for pinnipeds where
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males compete for “harems”
Other marine mammals copulate at sea
Sexual play is common in marine mammals
Mating grey whales—A second male may prop the female against mating male.
Reproduction in Marine Mammals
• Calves are born tail first so that they can
remain attached to the placenta until the
entire body is out and the animal can be
forced to the water’s surface to take its
first breath.
Dolphin giving birth
Most Important Characteristics
of Marine Reptiles, Seabirds,
and Marine Mammals