Marine Mammals:

Class Mammalia

Order Sirenia: Manatees and Dugongs

• 1 species of dugong• 3 species of manatees

Florida Manatee

• Endangered • Herbivore• Migrate in Winter• Inhabit tropical waters

Order Carnivora

• Well-developed claws.• Strong facial musculature• Specialized teeth: canines and incisors.

Suborder Pinnipedia: Sea Lions, Seals and the Walrus

Family Otariidae: Sea Lions

Family Phocidae: Seals

Comparison of Sea lions and Seals

Sea Lions (Otariids)• External ears• Long neck• Performs in shows• Use front flippers to

swim• Can pull hind flipper

under body to walk on land

• Claws ¾ to end of flipper

Seals (Phocids)• No external ears• Short neck• Do not perform• Use back flippers to

swim• Can’t rotate hind

flippers

• Claws at end of flippers

Family Odobenidae: Walrus

• Both males and females have tusks.

• Use vibrissae (whiskers) to feed.

Family Mustelidae: Sea Otter

Two North American Subspecies

1. The Alaska / Northern

2. The California / Southern

Sea Otter Fur• Over 1 million hairs/in2 (Humans have 20,000

hairs on their entire head!)• Need thick fur because they have NO

blubber• Oil on hair repels water

Oil Spills

• Oil covers fur and otters die of exposure• When otters attempt to clean their fur, they

ingest the oil and die.

Diet

• Eat invertebrates (urchins,abalone, crabs).• Use tools.

Polar Bears

Family Ursidae

• Partially aquatic bears.• Inhabit arctic sea ice, water islands &

coastlines.

Adaptations to the Arctic

• Small ears which help conserve body heat.

• Hind limbs are longer than forelimbs• 12’’ paws – act like snowshoes• Non-retractable claw (to grip ice)• Thick fur that is oily and water

repellent• Skin is black which enables the bear

to absorb sunlight energy to warm its body.

• Have 4 inches of blubber

• Need 4.4 lbs of fat a day to survive. • Polar bears can smell a seal more than 20

miles away.• Feed mainly seals, but will scavenge other

mammals

• No natural predators as adults• Threatened species protected under MMPA (Marine

Mammal Protection Act)• No hunting in U.S., but are hunted in Canada.

Whales

Order: Cetacea

Suborders:

1. Mysticeti = Baleen whales

2. Odontoceti =Toothed whales

Whale Anatomy

• Female whales have a genital slit and 2 mammary slits.

• Males have 1 genital slit.

Order Mysticeti (Baleen Whales)• Largest: Blue• 2nd largest: Fin • Humpback (sings)• http://www.oceanmammalinst.o

rg/songs/hmpback3.wav

• 2 Blowholes

Humpback

Minke Whale

Baleen

• Used for filter feeding• Grow down from upper jaw.

Rorqual• Many throat grooves• Shorter baleen plates

• Expand capacity of mouth

Diving Adaptations• Have 2x the RBC’s, and 9x

the myoglobin (than humans)

• Countercurrent heat exchange system

• Veins surround arteries; heat from blood in arteries is transferred to venous blood.

• Mammalian diving reflex- blood is shunted away from extremities to vital organs.

Gray Whale

Undertakes the longest migration (11,000 miles)

•

Order Odontoceti• Examples: Sperm,

Orca, Dolphins, Porpoises, Narwhal & Beluga

• Found in fresh and salt water

• Many toothed whales are countershaded or have disruptive coloration (killer whale)

• Sperm Whales have teeth in the lower jaw only!

• One Blowhole• No sense of smell in toothed whales

• Largest member of Dolphin family is Orca

• Largest toothed whale is the Sperm Whale

• Fastest is Dall’s Porpoise: 34 m.p.h.

Sperm Whale Dall’s Porpoise

Orca

Cooperative Hunting• Orcas, false killer whales, pilot whales, & bottlenose dolphins• Hunt in packs like wolves • Humpbacks use bubble netting to surround

their prey

Echolocation• Enables toothed whales

to locate and discriminate objects by listening for echoes

• Uses organ called a melon which contains fats

• Acts as an acoustical lens to focus sound waves out to H2O

• Sound travels 4x faster in H2O than in air.

• Lower jaw bones = sound reception