Marine MammalsMarine Mammals

Kingdom Animalia

Phylum Chordata

Class Mammalia

Marine Mammal characteristicsMarine Mammal characteristics

• All mammals share the following charac:• Hair• Nurse young (mammary gland)• Breathe air• Warm blooded• Live birth

5 groups of marine mammals5 groups of marine mammals

• Seals, Sea lions & Walruses

• Sea otters

• Polar bears

• Whales and Dolphins

• Manatees

Order CarnivoraOrder Carnivora

• SubOrder Pinnepedia• Seals, Sea Lions, Walruses

• Characteristics:• Pinneped means fin footed• Excellent swimmers• Thick layers of blubber to protect from cold• Make a barking sound• Nostrils can close for diving• Diet of mainly krill, crustacians, mollusks, fish, and

squid

PinnepedsPinnepeds

• Family Otariidae - eared seals include sea lions and fur seals.• Can rotate both

pectoral & pelvic fins to “walk” on land

PinnepedsPinnepeds

• Family Phocidae - are true seals. • They have no visible

ear flap.• No hind leg rotation• Front legs cannot

support their weight• Because they must

drag their back fins they are easy prey

PinnepedsPinnepeds

• Family Odobenidae - walruses • found only in North

Polar regions.• Use tusks to hoist

themselves onto the ice and to dig for clams

• Nearly became extinct due to humans killing them for their ivory tusks

• Most pinnepeds (except walruses) are covered with dense, waterproof fur that was attractive to man.

• Since the Marine Mammal Protection Act of 1972, hunting is illegal• As a result the shark has also experienced an

increase in population because it’s food source is readily available.

Sea OttersSea Otters

• Family Mustelidae• Smallest of the marine mammals• Four functioning limbs• Have no blubber

• Fur is dense and protects from cold

• Otter pups can’t swim so they float or rest on the mother’s stomach.

• Use tools such as rocks to break abalone• Use kelp to anchor themselves and young

Polar bears Polar bears

• Family Ursidae

• Only recently added to marine mammal list

• Extreme amounts of blubber

• Fur is transparent

• Skin is black

• Feet look like snowshoes and are webbed

• Cover their nose when hunting as not to be detected.

Order CetaceaOrder Cetacea

• Whales, dolphins, and porpoises• Grouped by their mouth structures• Family Mysteceti - baleen whales• Family Odontoceti - toothed whales

Blue whale Dolphin

Family MystecetiFamily Mysteceti

• Possess baleen to strain plankton

• Ex. right, humpback, blue

• 2 nostrils and 2 blow holes

• Eat large amount of food that is low on the food chain

• Dorsal fin is reduced in size or absent in larger whales

Right Whale

Right whale

Sperm whale

Family OdontocetiFamily Odontoceti

• Known as toothed whales because of their conical shaped teeth

• Ex: sperm whale, orca, dolphins

• 2 nostril but only 1 blow holePorpoise

• Cetaceans are protected by the Marine Mammal Protection Act of 1972. This act made whaling illegal in US coastal waters

• Many are still being hunted under the guise of scientific research or are “by-catch” of the tuna fishery

• The International Whaling Commission (I.W.C.) is a whalers organization that sets quotas based on catch size.• Problems with the IWC is that it is strictly voluntary

and actual is set to protect the whaling industry not the whales.

Cetacean adaptationsCetacean adaptations

• Swimming - use powerful tail flukes• Fluke markings are used like fingerprints for identification

• Digestion - multi-compartmentalized stomachs “chew” food. • Even toothed whales don’t chew their food• Baleen whales eat krill and plankton• Toothed whales eat fish, penguins, seals…

Narwhal

Bowhead Right whale

Grey whale

Cetacean adaptationsCetacean adaptations

• Circulation - 4 chambered heart

• Blubber insulates against the cold.

• Possess counter current heat exchange which keeps the whale from overheating. • Can transfer arteriole heat to surface tissues

(flukes and fins)

• Senses - vision is poor, uses echolocation to compensate

Cetacean adaptationsCetacean adaptations

• Whales have no vocal chords but make clicks and whines by vibrations in the blow hole

• Sounds are emitted and amplified in the head through an oil filled cavity called a melon

• Incoming vibrations are focused through the jaw and melon to the inner ear and the brain

Cetacean adaptationsCetacean adaptations

• Diving - lungs are emptied and filled quickly through blow hole on top of head• A trachea under the blow hole connects directly

to lungs• Nasal passages close when relaxed to prevent

water from entering the lungs• Oxygen is stored in muscles, ribs are

collapsible to reduce internal air pockets

• Whale strandings occur when they are ill to prevent drowning

Cetacean adaptationsCetacean adaptations

• Excretory - specialized kidneys allow whales to drink salt water. Urine has high salinity content

• Reproduction - internal• Mating occurs in early summer, gestation lasts

7 months so the egg implantation is delayed 4 months so that the baby is born in the warm summer months

• Most whales have 1 calf every 2-3 years• Whale milk is unusually high in fat content

Whale migrationsWhale migrations

• Are timed to coincide with• Weather

• Mating

• Migrations of other fish

• Births

Humpback

Orca

Pilot whale

Order SireniaOrder Sirenia

• Manatees or Sea cows

• Protected by the state of Florida since 1893

• Protected by the Endangered Species Act of 1973

• Protected by the Marine Mammal Protection Act of 1972

• BUT ONLY AROUND 1200 STILL SURVIVE TODAY

5 populations in the Order Sirenia

5 populations in the Order Sirenia

• Family Dugongidae• Dugong

• Found in Australia and Indonesia

• Notched tail fluke

• Stellar Sea Cow• Hunted to extinction

within 27 years of its discovery in 1741

• Family Trichechidae• West Indian manatee

• Found from Florida to Brazil

• Round paddle shaped tail

• Amazonian manatee

• West African manatee

ManateesManatees

• Manatees are related to the elephant through biochemistry and external features

• Average 10’ in length and weighs ~ 1000lbs

• Use blubber to keep warm

• Herbivores that may eat 100 lbs of sea grass a day

Manatee characteristicsManatee characteristics

• Their constant eating helps keep channels clear. Ironically this causes 50% of deaths due to careless boaters.

• Manatees must surface to breathe• Whiskers (vibrissae) on snout used to rake

in plants• Nurse young for a year. Mammary glands

are located under flippers

Manatee characteristicsManatee characteristics

• Live birth - gestation period of 13 months• Produce 1 calf ever 3-5 years

• Large brain, poor vision• Warm blooded with 4 chambered heart• Stomach has compartments, it ruminates (chews

its cud)• Breathes air - may dive for 20 minutes• Tail - horizontal paddle• Can produce high pitched whistle for

communication

Manatee characteristicsManatee characteristics

• Because they have no predators • they have no social

structure,

• not territorial,

• herds don’t have a leader,

• no permanent bonds are formed for mating