Marine Mammals

Life history, ecology and conservation

WHO ARE THEY?

Cetacea

whales, dolphins, and porpoises

Carnivora

polar bears, otters, seals, sea lions, walruses

Sirenia

manatees and dugongs

CETACEA: Toothed whales

Bottlenose dolphin

Striped dolphin

Common dolphin

Risso’s dolphin

Focena comune

Globicephalo...

Killer whale

False killer whale

Rough-toothed dolphin

Risso’s dolphin

Harbor porpoise

Pilot whale

Sperm whale...

Cuvier’s beaked whale

...Sperm whale

DNA

CETACEA:

Baleen whales

Fin whale

Right whale

Sei whale

Humpback whale

CARNIVORA:

Pinnipeds

Otariidae

sea lions, fur seals, etc

Phocidae

true seals

Otariidae

ear pinnae

eye

sagittal crest

snout

whiskers

mane

fore flippers

tail

scrotum

hind flippers

hind flippers

tail

whiskers(vibrissae) fore flippers

claws

snouteye

ear

Phocidaeor True seals

CARNIVORA:

Pinnipeds

Odobenidae

walruses

CARNIVORA:

Ursidae

polar bears

CARNIVORA:

Mustelidae

sea otters, weasels, minks, etc

SIRENIA:

Trichechidae

manatees

Dugongidae

dugongs, Stellar’s sea cows

This presentation will focus...

...on dolphins and whales (cetaceans)!

Some terminology....

    

                                                        

FROM LAND TO SEA

50 MILLION YEARS AGO 45 MILLION

YEARS AGO

40 MILLION YEARS AGO

35 MILLION YEARS AGO

30 MILLION YEARS AGO

25 MILLION YEARS AGO

20 MILLION YEARS AGO 15 MILLION

YEARS AGO

MESONICHIDAE

PROTOCETIDAEDORYDONTIDAE

SQUALODONTIDAE

DELPHINIDAE

DIVERGENCE

ADAPTATIONS

ADAPTATIONS

Dog

ADAPTATIONS

Underwater life:

• Streamlined body

• Fins

• Head and skull

• Eyes and ears

• Heat conservation

• Salt balance

• Buoyancy

• Genital protrusion, etc

   

Nostril migration

ADAPTATIONS

• breathing system

ADAPTATIONS

• breathing system

ADAPTATIONS

Perfectly adapted to marine environment!

What are the differences?

DIFFERENCES

DIFFERENCES

baleen

ventral groovestonguejaw

DIFFERENCES

feeding Feeding

Humpback whales

Feeding

Gray whales

Feeding

Gray whales

Feeding

Other whales

Teeth

DIFFERENCES

Teeth

DIFFERENCES

HOW DO YOU DETERMINE THE AGE OFHOW DO YOU DETERMINE THE AGE OFA DOLPHIN AND A WHALE?A DOLPHIN AND A WHALE?

Feeding

Group waiting to feed

Sentinel

Dolphins feeding

Sentinel

Feeding

Bottlenose dolphin

Feeding

Common dolphin

Feeding

Killer whale

Feeding

Sperm whale

Feeding

OTHER CAPTURE TECHNIQUES:

“crater feeding”

“fish whacking”

“strand feeding”

How dolphins find their prey?

How echolocation works?

Returning echo

Sound emission

Where is the food?

Migration...

... and residency

How dolphins move

Great variety of cetaceans

Tongue =

Heart =

Blue whale

Distribution

cold waters

rivers

tropical waters

Group sizes

Small schools

Large schools

Single/Pairs

Groups

• Advantages

• Disadvantages

Schools, pods & herds

SOCIAL BEHAVIOR

Fission-fusion societies

                                             

   

 

Complex societies

Alliances and Superalliances

Courtship & Mating

Not easily distinguishable....

female

male

navel anusgenital slit

mammary slit

Birth

Long term bonds

Cetaceans’ sensory world

• Sight

• Smell

• Taste

• Touch

• Sound

Cetaceans’ sensory world

SOUND

• Communication whistles

• Echolocation clicks

Song of a whale

Dolphin whistles

Cetaceans’ sensory world

Modern humans=7.06Great apes=1.91Odontocetes=3.78Odontocetes=3.78

Brain and intelligence

Social learning

“Culture”

Self-recognition

Sponge carrying

Unique mammals

As humans increase their exploitation of marine As humans increase their exploitation of marine resources, individual dolphins, porpoises resources, individual dolphins, porpoises and whales suffer, their societies and whales suffer, their societies are disrupted, and their populations declineare disrupted, and their populations decline

(Whitehead et al. 2000)

Worldwide threats to cetaceans

WHAT ARE THE MOST IMPORTANT WHAT ARE THE MOST IMPORTANT ANTHROPOGENIC THREATS TO MARINE ANTHROPOGENIC THREATS TO MARINE MAMMALS?MAMMALS?

Present exploitation

• Aboriginal hunts

• Hunts in or by developing countries

• Whaling for scientific purpose

• Live capture

By-catch

“It refers to the incidental capture of non-target species in fisheries” (Whitehead et al. 1999)

Effects nearly every cetacean species

By-catch

Often unsustainable

Primary cause of population decline

May bring species close to extinction

560 <200

Habitat loss and degradation

Serious threat to inshore, freshwater species

Pollution

Oceans as

infinite trash

dumps...!?!

Competition with fisheries

likely to be a threat

BUT...

conclusive evidence is lacking due to complex ecosystem dynamics

Humans: use sounds in same wide range of frequencies to explore oceans

Noise is incidentally produced by most marine activities

Humans have potential to interfere acoustically with the lives Humans have potential to interfere acoustically with the lives of cetaceansof cetaceans

Noise and disturbance

Collisions with ships

Significant impact on mid/large cetaceans in areas of high/fast ship traffic

Global climate changes

“It’s generally agreed that the Earth’s climate is changing systematically in response to human activities” (Intergovernmental Panel on Climate Change 1995)

“These changes are likely to affect virtually all life, including cetaceans” (IWC 1997)

Thank you!