Major fresh water mammals, marine mammals taxonomic position, identification and distribution around the world

1. MAJOR AQUATIC MAMMALS AND
THEIR IMPORTANCE
By:
Bhukya Bhaskar
Fisheries
Global Distribution and conservation
of marine Mammals
Smithsonian Institution

2. Introduction
• Aquatic and semiaquatic mammals are a diverse group of mammals that dwell partly or entirely in bodies of
water.
• They include the various marine mammals who dwell in oceans, as well as various freshwater species, such as
the European otter.
• Aquatic and semiaquatic mammals are well adapted to life in the water with physical characteristics such
as flippers, webbed feet, paddlelike tails and streamlined bodies. Whales, dolphins, porpoises, manatee
and dugong are completely aquatic; seals, sea lions, walrus, hippopotamus, platypus, otters, beavers and
nutria are semiaquatic, spending part of their lives on land.
• They are not a taxon and are not unified by any distinct biological grouping, but rather their dependence on and
integral relation to aquatic ecosystems.
• The level of dependence on aquatic life varies greatly among species.
• Among freshwater taxa, the Amazonian manatee and river dolphins are completely aquatic and fully dependent
on aquatic ecosystems.
• Semiaquatic freshwater taxa include the Baikal seal, which feeds underwater but rests, molts, and breeds on
land; and the capybara and hippopotamus which are able to venture in and out of water in search of food.
• Mammal adaptation to an aquatic lifestyle vary considerably between species.
• River dolphins and manatees are both fully aquatic and therefore are completely tethered to a life in the water.
• Seals are semiaquatic; they spend the majority of their time in the water, but need to return to land for important
activities such as mating, breeding and molting.
• In contrast, many other aquatic mammals, such as hippopotamus, capybara, and water shrews, are much less
adapted to aquatic living.
• Likewise, their diet ranges considerably as well, anywhere from aquatic plants and leaves to small fish and
crustaceans.
• They play major roles in maintaining aquatic ecosystems, beavers especially.
• Aquatic mammals were the target for commercial industry, leading to a sharp decline in all populations of
exploited species, such as beavers.
• Their pelts, suited for conserving heat, were taken during the fur trade and made into coats and hats.

3. mammals that live in freshwater
• Order Sirenia: sirenians
– Family Trichechidae: manatees
• Amazonian manatee (Trichechus inunguis)
• African manatee (Trichechus senegalensis)
• Order Cetartiodactyla: even-toed
ungulates
– Suborder Whippomorpha
• Family Platanistidae
– Ganges river dolphin, or susu (Platanista
gangetica)
– Indus river dolphin, or bhulan (Platanista minor)
• Family Iniidae
– Amazon river dolphin, or boto (Inia geoffrensis)
– Araguaian river dolphin (Inia araguaiaensis)
• Family Lipotidae
– Chinese river dolphin, or baiji (Lipotes vexillifer)
possibly extinct
• Family Pontoporiidae
– La Plata dolphin, or franciscana (Pontoporia
blainvillei)
• Family Hippopotamidae: hippopotamuses
– Hippopotamus (Hippopotamus amphibius)
– Pygmy hippopotamus (Choeropsis liberiensis)
An Amazon river dolphin (Inia
geoffrensis), a member of the
infraorder Cetacea of the
order Cetartiodactyla

4. Cont..
• Order Carnivora
– Family Mustelidae
• Subfamily Lutrinae
– Eurasian otter (Lutra lutra)
– Hairy-nosed otter (Lutra sumatrana)
– Spotted-necked otter (Hydrictis maculicollis)
– Smooth-coated otter (Lutrogale perspicillata)
– North American river otter (Lontra canadensis)
– Southern river otter (Lontra provocax)
– Neotropical river otter (Lontra longicaudis)
– Giant otter (Pteronura brasiliensis)
– African clawless otter (Aonyx capensis)
– Oriental small-clawed otter (Aonyx cinerea)
• Subfamily Mustelinae
– European mink (Mustela lutreola)
– American mink (Neogale vison)
– Family Phocidae
• Genus Pusa
– Baikal seal (Pusa sibirica)
– Ladoga seal (Pusa hispida ladogensis)
– Saimaa seal (Pusa hispida saimensis)
• Order Rodentia: rodents
– Suborder Hystricomorpha
• Capybara (Hydrochoerus hydrochaeris)
• Lesser capybara (Hydrochoerus isthmius)
• Coypu (Myocastor coypus)
– Family Castoridae: beavers
• North American beaver (Castor canadensis)
• Eurasian beaver (Castor fiber)
– Family Cricetidae
• Muskrat (Ondatra zibethicus)
• European water vole (Arvicola amphibius)
• Order Monotremata: monotremes
– Platypus (Ornithorhynchus anatinus)
• Order Afrosoricida
– Giant otter shrew (Potamogale velox)
• Order Eulipotyphla
– Family Soricidae: shrews
• Malayan water shrew (Chimarrogale hantu)
• Himalayan water shrew (Chimarrogale himalayica)
• Sunda water shrew (Chimarrogale phaeura)
• Japanese water shrew (Chimarrogale platycephala)
• Chinese water shrew (Chimarrogale styani)
• Sumatran water shrew (Chimarrogale sumatrana)
• Elegant water shrew (Nectogale elegans)
• Mediterranean water shrew (Neomys anomalus)
• Eurasian water shrew (Neomoys fodiens)
• Transcaucasian water shrew (Neomys teres)
• Glacier Bay water shrew (Sorex alaskanus)
• American water shrew (Sorex palustris)
• Pacific water shrew, or marsh shrew (Sorex bendirii)
– Family Talpidae (moles and relatives)
• Russian desman (Desmana moschata)
• Order Didelphimorphia: opossums
– Family Didelphidae: opossums
• Big lutrine opossum (Lutreolina crassicaudata)
• Massoia's lutrine opossum (Lutreolina massoia)
• Yapok (Chironectes minimus)

5. Marine mammals
• Marine mammals are aquatic
mammals that rely on the ocean
for their existence.
• They include animals such as sea
lions, whales, dugongs, sea
otters and polar bears. Like other
aquatic mammals,
• Both cetaceans and sirenians are
fully aquatic and therefore are
obligate ocean dwellers.
• Pinnipeds are semiaquatic; they
spend the majority of their time in
the water, but need to return to
land for important activities such as
mating, breeding and molting.
• In contrast, both otters and
the polar bear are much less
adapted to aquatic living.
• Their diet ranges considerably as
well; some may eat zooplankton,
others may eat small fish, and a
few may eat other mammals.
• While the number of marine
mammals is small compared to
those found on land, their roles in
various ecosystems are large.
• They, namely sea otters and polar
bears, play important roles in
maintaining marine ecosystems,
especially through regulation of
prey populations..
• Their role in maintaining
ecosystems makes them of
particular concern considering
25% of marine mammal species
are currently threatened

6. Adaptations
• Mammals evolved on land, so all aquatic and semiaquatic mammals
have brought many terrestrial adaptations into the waters.
• They do not breathe underwater as fish do, so their respiratory
systems had to protect the body from the surrounding
water; valvular nostrils and an intranarial larynx exclude water
while breathing and swallowing.
• To navigate and detect prey in murky and turbid waters, aquatic
mammals have developed a variety of sensory organs: for example,
manatees have elongated and highly sensitive whiskers which are
used to detect food and other vegetation directly front of
them, and toothed whales have evolved echolocation.
• Aquatic mammals also display a variety of locomotion styles.
Cetaceans excel in streamlined body shape and the up-and-down
movements of their flukes make them fast swimmers; the tucuxi,
for example, can reach speeds of 14 miles per hour (23 km/h).
• The considerably slower sirenians can also propel themselves with
their fluke, but they can also walk on the bottom with their
forelimbs.[
• The earless seals (Phocidae) swim by moving their hind-flippers and
lower body from side to side, while their fore-flippers are mainly
used for steering.
• They are clumsy on land, and move on land by lunging, bouncing
and wiggling while their fore-flippers keep them balanced;[ when
confronted with predators, they retreat to the water as freshwater
phocids have no aquatic predators.
• Some aquatic mammals have retained four weight-bearing limbs
(e.g. hippopotamuses, beavers, otters, muskrats) and can walk on
land like fully terrestrial mammals.
• The long and thin legs of a moose limit exposure to and friction
from water in contrast to hippopotamuses who keep most of their
body submerged and have short and thick legs.
• The semiaquatic pygmy hippopotamus can walk quickly on a
muddy underwater surface thanks to robust muscles and because
all toes are weight-bearing.
• Some aquatic mammals with flippers (e.g. seals) are amphibious
and regularly leave the water, sometimes for extended periods, and
maneuver on land by undulating their bodies to move on land,
similar to the up-and-down body motion used underwater by fully
aquatic mammals (e.g. dolphins and manatees).
• Beavers, muskrats, otters, and capybara have fur, one of the
defining mammalian features, that is long, oily, and waterproof in
order to trap air to provide insulation.
• In contrast, other aquatic mammals, such as dolphins, manatees,
seals, and hippopotamuses, have lost their fur in favor of a thick
and dense epidermis, and a thickened fat layer (blubber in response
to hydrodynamic requirements.
• Wading and bottom-feeding animals (e.g. moose and manatee)
need to be heavier than water in order to keep contact with the
floor or to stay submerged, surface-living animals (e.g. otters) need
the opposite, and free-swimming animals living in open waters (e.g.
dolphins) need to be neutrally buoyant in order to be able to swim
up and down the water column.
• Typically, thick and dense bone is found in bottom feeders and low
bone density is associated with mammals living in deep water.
• The shape and function of the eyes in aquatic animals are
dependent on water depth and light exposure: limited light
exposure results in a retina similar to that of nocturnal terrestrial
mammals.
• Additionally, cetaceans have two areas of high ganglion
cell concentration ("best-vision areas"), where other aquatic
mammals (e.g. seals, manatees, otters) only have one.
• Among non-placental mammals, which cannot give birth to fully
developed young,some adjustments have been made for an
aquatic lifestyle.
• The yapok has a backwards-facing pouch which seals off completely
when the animal is underwater, while the platypusdeposits its
young on a burrow on land.

7. Whales
• Whales have streamlined bodies tapering toward the horizontal tail that
distinguishes them from fish.
• Their front limbs have been modified into broad flippers.
• Whales lack back limbs and external ears.
• A thick layer of blubber beneath their skin helps to conserve heat.
• Whalebone whales do not have teeth, but plates of baleen or whalebone in their
V-shaped upper jaw, which act as sieves or strainers for plankton.
• The coarse, frayed inner edges catch the tiny creatures on which the whale
feeds.
• Whalebones are the largest whales -- the blue whale, the largest animal ever
known to have lived, reaches up to 100 feet and 200 tons.
• Whalebones include the Californian gray whale, rorquals or fin whales, blue
whales and the Greenland right whale.
• Toothed whales are much smaller than the whalebone whales.
• They have conical, pointed teeth in the lower or both jaws, or one tusklike tooth
in the upper jaw. Toothed whales feed primarily on fish.
• Whales in this suborder include river dolphins, beaked whales, sperm whales,
beluga or white whales, narwhal, killer whales, Atlantic bottlenose dolphins and
the common or harbor porpoise.
1. Blue Whales Can Grow More Than 100 Feet Long
• They are gigantic, generally ranging in length from 80 to 100 feet (24 to 30
meters). The longest, accurately measured blue whale is a female who was
measured at 97 feet (23.5 meters)—but there are reports of blue whales that
reached 108 feet (33 meters) in length.1 Just how big is that? Imagine three
school buses back to back.
2. They Can Weigh as Much as 30 Elephants
• The average weight for these gentle giants is 200,000 to 300,000 pounds (90,000
to 136,000 kilograms), or about 100 to 150 tons. Some can weigh as much as
441,000 pounds (200,000 kilograms) or 220 tons. For comparison, an adult
African bush elephant weighs up to 6 tons, so it may take 30 or more elephants
to equal the weight of one blue whale.
• 3. They Have Big Hearts
• The blue whale's heart is huge. It's the largest heart in the animal kingdom,
weighing about 400 pounds (180 kilograms)—about the same weight as a gorilla
and roughly the size of a bumper car. As a blue whale dives to feed, its giant
heart may only beat twice per minute.
• 4. They Have Big Tongues, Too
• A blue whale’s tongue alone can weigh as much as an elephant.
• 5. They Have the Biggest Babies on Earth
• Blue whale calves are the biggest babies on Earth, easily, and at birth already rank among the
largest full-grown animals. They pop out at around 8,800 pounds (4,000 kg) with a length of
some 26 feet (8 meters). They gain 200 pounds (90 kg) a day! Their growth rate is likely one of
the fastest in the animal world, with a several billion-fold increase in tissue in the 18 months
from conception to weaning.
• 6. They’re Unusually Loud
• Blue whales, in fact, are the loudest animals on the planet. A jet engine registers at 140
decibels; the call of a blue whale reaches 180. Their language of pulses, groans, and moans can
be heard by others up to 1,000 miles (1,600 kilometers) away.
• 7. They Eat a Lot of Krill
• (. Blue whales feast on krill; their stomachs can hold 2,200 pounds (1,000 kilograms) of the tiny
crustaceans at a time. They require almost 9,000 pounds (4,000 kilograms) of the little guys a
day and around 40 million krill daily during the summer feeding season.
• Blue whales travel a lot, spending summers feeding in polar regions and making the long trip to
the equator as winter comes along. While they have a cruis ing speed of 5 mph (8 kph), they
can accelerate up to 20 mph (32 kph) when needed.
• 9. They Have Long Life Spans
• Blue whales are among the planet’s longest-lived animals. Kind of like counting tree rings,
scientists count layers of wax in the ears and can determine a ballpark age. The oldest blue
whale they’ve discovered this way was calculated to be around 100 years old, though the
average life is thought to be around 80 to 90 years.
• 10. They Once Were Abundant
• Before whalers discovered the treasure trove of oil that a blue whale could provide, the species
was plentiful. But with the advent of 20th-century whaling fleets, their population plummeted
until finally receiving worldwide protection in 1967. From 1904 to 1967, more than 350,000 blue
whales were killed in the Southern Hemisphere, according to the World Wildlife Fund. In 1931,
during the heyday of whaling, an astounding 29,000 blue whales were killed in a single season.
• 11. Their Future Remains Uncertain
• While commercial whaling is no longer a threat, recovery has been slow and new threats plague
blue whales, like ship strikes and the impact of climate change. There is one population of
around 2,000 blue whales off the coast of California, but all told there are only around 10,000
to 25,000 individuals left. The International Union for Conservation of Nature lists the species as
endangered. Hopefully with time, the planet’s largest gentle giants will again roam the seas
aplenty.

8. True or Earless Seals and Sea Lions
• True seals are also known as earless seals, or simply "seals".
• In and around RNSP, there are two seal species to be found,
the harbor seal (Phoca vitulina), and northern elephant seal
(Mirounga angustirotris)
• Seals live in the oceans of the Northern and Southern
hemispheres, primarily in polar, subpolar and temperate
climates, with the exception of tropical monk seals.
• These semiaquatic carnivores have a streamlined shape,
flippers and webbed feet.
• They have no visible external ears.
• Millions of years of adaptation to the sea have made seals
expert swimmers and divers, but they are quite awkward on
land.
• A thick layer of oily fat or blubber up to 3 inches thick
insulates them by maintaining a body temperature around
100 degrees Fahrenheit.
• Among the 18 species are leopard seal, harp seal, common
or harbor seal, gray seal, Weddell seal, spotted seal, ringed
seal and Baikal seal.
• Sea lions have conspicuous external ears. Their four limbs
give them good mobility on land.
• The 13 species of sea lions are divided into two groups,
sea lions and fur seals.
• The California sea lion, native to the southwest coast of
North America, is the most abundant species of sea lion.
• The northern fur seal migrates in winter from the Bering
Sea to California and Japan.
• Sea lions can be noisy, and recognized by their loud and
distinct “bark.” They commonly congregate in large groups
called “herds” or “rafts.” They can be seen hauled out
together on offshore rocks, sandy beaches, and sometimes
human-made structures such as jetties and piers.

9. Walrus
• The walrus is found in the Arctic
Ocean and in subarctic seas.
• Walruses spend much of their
time on land, but they are
graceful in water.
• They dive up to 180 feet deep for
clams and shellfish on the ocean
floor, staying underwater for up
to 30 minutes.
• The adult male walrus weighs
more than 2,000 pounds.
• Its upper canines form tusks up
to 27 inches long that it hooks
into ice floes to pull itself out of
the water.
• Walruses live up to 40 years in
the wild.
• Scientific classification Domain:Eukaryota
Kingdom:Animalia Phylum:Chordata
Class:Mammalia Order:Carnivora
• Clade:Pinnipedia
• Family:Odobenidae
• Genus:Odobenus
Brisson,1762Species:O. rosmarus
Binomial name: Odobenus rosmarus
(Linnaeus, 1758)

10. Manatees
• Manatees are completely aquatic, but
like all marine mammals they need to
breathe.
• While resting they can stay submerged
for up to 15 minutes; while swimming
they need to breathe at the surface
every three or four minutes.
• Found along the coasts and estuaries
of Florida, Central America and the
West Indies, the massive, slow-moving
North American manatee is one of
three species of manatee.
• It grows up to 13 feet long and weighs
up to 1,300 pounds.
• Its diet is composed of water grasses,
weeds and algae, and it eats as much
as one-tenth of their body weight
every day.
• The average life span in the wild is up
to 40 years.
• Scientific classification Domain:Eukaryota
• Kingdom:Animalia
• Phylum:Chordata
• Class:Mammalia
• Order:Sirenia
• Family:Trichechidae
• Subfamily:Trichechinae
• Genus:Trichechus
Linnaeus 1758Type speciesTrichechus manatus
Linnaeus, 1758
• Species: Trichechus hesperamazonicus
• Trichechus inunguis
• Trichechus manatus
• Trichechus senegalensis
• Trichechus "pygmaeus“ (validity questionable)

11. Dugong
• Dugongs grow up to 10 feet long and
weigh 510 to 1,100 pounds. They are
closely related to manatees, and they
never leave the water.
• Unlike the manatee they have a hairless
body and a fluked horizontal tail like a
whale's.
• They can stay underwater for up to six
minutes.
• Frequenting the warm coastal waters of
the western Pacific, Indian Ocean and
Red Sea, dugongs are often observed
alone or in pairs, and sometimes in
herds of more than 100.
• Dugongs root for water grasses day and
night.
• Docile dugongs are long-lived in the
wild, with an average life span up to 70
years.
• TN declared 500 sqkm in Palk Bay as a
1st dugong conservation reserve in
India.
• Scientific classification
• Domain:Eukaryota
• Kingdom:Animalia
• Phylum:Chordata
• Class:Mammalia
• Order:Sirenia
• Family:Dugongidae
• Subfamily:Dugonginae
• Genus:Dugong
Lacépède, 1799Species:D. dugon
• Binomial name: Dugong dugon
(Müller, 1776)

12. Hippopotamus
• Hippopotamus loves water
and stays submerged up to 16
hours of the day.
• With its eyes and nostrils set
high up on its head, it is often
tall enough to stay submerged
and breathe at the same time.
Hippopotami leave the water
at dusk to feed on land
vegetation.
• Found only in rivers in Africa,
hippopotami are between 10
and 15 feet long including the
tail.
• They weigh 5,000 to 8,000
pounds and live an average of
40 years in the wild.
• Scientific classification Domain:Eukaryota
• Kingdom:Animalia
• Phylum:Chordata
• Class:Mammalia
• Order:Artiodactyla
• Family:Hippopotamidae
• Genus:Hippopotamus
• Species:H. amphibius
• Binomial name Hippopotamus amphibius
Linnaeus, 1758

13. River and Sea Otters
• Semiaquatic river otters, like other amphibious mammals,
have dense, thick fur and streamlined bodies designed for
life in the water.
• There are several species; the North American river otter
lives along rivers, lakes and large creeks.
• River otters weigh up to 18 pounds and reach up to 4 feet
long, including their tail.
• Sea otters are the largest member of weasel family, and the
only one that lives almost entirely in the water -- hunting on
the ocean floor, and coming to the surface to eat, groom,
rest and socialize with other otters.
• The average adult grows up to 5 feet long and weighs up to
70 pounds -- females are slightly smaller.
• Populations throughout southeast Alaska, British Columbia
and Washington are stable and increasing, while the
numbers of sea otters in southwest Alaska are declining
mainly because of predation by the killer whale.
• The sea otter (Enhydra lutris) is a marine mammal native to
the coasts of the northern and eastern North Pacific Ocean,
Adult sea otters typically weigh between 14 and 45 kg (30
and 100 lb), making them the heaviest members of
the weasel family, but among the smallest marine
mammals.
• Unlike most marine mammals, the sea otter's primary form
of insulation is an exceptionally thick coat of fur, the
densest in the animal kingdom. Although it can walk on
land, the sea otter is capable of living exclusively in the
ocean.
• Sea otters can live up to 25 years in the wild
• Scientific classification
• Domain:Eukaryota
• Kingdom:Animalia
• Phylum:Chordata
• Class:Mammalia
• Order:Carnivora
• Family:Mustelidae
• Subfamily:Lutrinae
• Genus:Enhydra
• Species:E. lutris
• Binomial name: Enhydra lutris
(Linnaeus, 1758)
• SubspeciesE. l. lutrisE. l. kenyoniE. l. nereis

14. Beavers, Nutria and Muskrat
• Primarily aquatic, beavers are found in rivers and lakes in Europe, Asia and throughout North America, except
northern Canada, the southern deserts of the United States and Mexico.
• They have a waterproof coat, closable ears, closable nostrils, paddle-shaped tail and webbed feet.
• These 30- to 50-pound rodents can greatly change whole environments with their dam-building activities.
• Introduced intentionally and accidentally to North America, the nutria or coypus is native to Central and
South America.
• It weighs up to 25 pounds.
• Well adapted to a semiaquatic life, nutria have small eyes and ears, and large, webbed hind feet for
swimming.
• Muskrats are good swimmers and can stay underwater up to 17 minutes, preferring to live in 4 to 6 feet of
water.
• Found in swamps, marshes, and wetlands from northern North America to the Gulf coast and the Mexican
border, they are about 2 feet long and up to 4 pounds.

15. Duck-billed Platypus
• The platypus (Ornithorhynchus
anatinus), sometimes referred to as the duck-
billed platypus, is a semiaquatic, egg-
laying mammal endemic to eastern Australia,
including Tasmania.
• The platypus is the sole living representative
or monotypic taxon of
its family (Ornithorhynchidae)
and genus (Ornithorhynchus), though a
number of related species appear in the fossil
record.
• The duck-billed platypus lives in the
freshwater rivers and streams of eastern
Australia, Tasmania and New Guinea.
• It lays eggs and has a long, leathery bill
equipped with electroreceptors that help
detect the magnetic fields of the aquatic
invertebrates it feeds upon.
• Platypus are up to 2 feet long and 4 pounds.
Their average life span in the wild is up to 17
years.
• Scientific classification
• Domain:Eukaryota
• Kingdom:Animalia
• Phylum:Chordata
• Class:Mammalia
• Order:Monotremata
• Family:Ornithorhynchidae
• Genus:Ornithorhynchus
Blumenbach, 1800Species:O. anatinus
• Binomial name: Ornithorhynchus anatinus
(Shaw, 1799)

16. References
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Meghan Marchetti/DWR
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geographic_fig3_221808992
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• https://ocean.si.edu/ocean-life/marine-mammals/what-largest-whale-
cetacea-size-comparison-chart
Global hotspots of marine mammal species extinction risk, overlaid with the geographic
distributions of the leading human impacts (1) on marine mammals and with Marine
Protected Areas (MPAs) (39). (A) Fishing intensity. (B) Ship traffic and pollution. (C)
Seasurface temperature change: 1985–2005. (D) World distribution of MPAs (see also Fig.
S6 for magnified view of D). Hotspots show the top 2% of geographic grid cells for at-risk
species (model-predicted plus IUCN Red List species). Maps A, B, and C show examples of
species predicted to be at risk by our model that occur within the hotspots, or other highly
impacted regions, and whose populations are threatened by fishing, shipping, pollution, or
climate change. Drawings are by Sharyn N. Davidson.