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
Killerdolphin
whale
False
Focena
killer
comune
whale
Rough-toothed dolphin
Globicephalo...
Risso’s dolphin
Pilot whale
Harbor porpoise
Cuvier’s beaked whale
Sperm whale...
...Sperm whale
CETACEA:
Baleen whales
Fin whale
Right whale
Sei whale
Humpback whale
CARNIVORA:
Pinnipeds
Otariidae
sea lions, fur seals, etc
Phocidae
true seals
sagittal
crest
snout
Otariidae
eye
ear pinnae
whiskers
mane
tail
scrotum
fore flippers
hind flippers
Phocidae
or
True seals
snout
eye
ear
claws
whiskers
(vibrissae) fore flippers
hind flippers
tail
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
MESONICHIDAE
PROTOCETIDAE
50 MILLION
YEARS AGO
DORYDONTIDAE
45 MILLION
YEARS AGO
SQUALODONTIDAE
40 MILLION
YEARS AGO
35 MILLION
YEARS AGO
30 MILLION
YEARS AGO
DELPHINIDAE
25 MILLION
YEARS AGO
20 MILLION
YEARS AGO
15 MILLION
YEARS AGO
DIVERGENCE
ADAPTATIONS
ADAPTATIONS
Dog
ADAPTATIONS
Underwater life:
• Streamlined body
• Fins
• Head and skull
• Eyes and ears
• Heat conservation
• Salt balance
• Buoyancy
• Genital protrusion, etc
ADAPTATIONS
• breathing system
Nostril migration
ADAPTATIONS
• breathing system
ADAPTATIONS
Perfectly adapted to marine environment!
What are the differences?
DIFFERENCES
DIFFERENCES
baleen
jaw
tongue
ventral grooves
DIFFERENCES
Feeding
feeding
Humpback whales
Feeding
Gray whales
Feeding
Gray whales
Feeding
Other whales
DIFFERENCES
Teeth
DIFFERENCES
Teeth
HOW DO YOU DETERMINE THE AGE OF
A DOLPHIN AND A WHALE?
Feeding
Group
waiting
to feed
Dolphins
feeding
Sentinel
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
Blue whale
Heart =
Tongue =
Distribution
cold waters
tropical waters
rivers
Group sizes
Small schools
Large schools
Single/Pairs
Groups
Schools, pods & herds
•
Advantages
•
Disadvantages
SOCIAL BEHAVIOR
Fission-fusion societies
Complex societies
Alliances and Superalliances
Courtship & Mating
Not easily distinguishable....
mammary slit
female
navel
genital slit
anus
male
Birth
Long term bonds
Cetaceans’ sensory world
• Sight
• Smell
• Taste
• Touch
• Sound
Cetaceans’ sensory world
SOUND
• Communication
whistles
• Echolocation
clicks
Cetaceans’ sensory world
Song of a
whale
Dolphin
whistles
Brain and intelligence
Modern humans=7.06
Great apes=1.91
Odontocetes=3.78
Social learning
“Culture”
Sponge carrying
Self-recognition
Unique mammals
As humans increase their exploitation of marine
resources, individual dolphins, porpoises
and whales suffer, their societies
are disrupted, and their populations decline
(Whitehead et al. 2000)
Worldwide
threats to
cetaceans
WHAT ARE THE MOST IMPORTANT
ANTHROPOGENIC THREATS TO MARINE
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
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
Noise and disturbance
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
of cetaceans
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!