This presentation will focus......on dolphins and whales (cetaceans)!
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 PROTOCETIDAE DORYDONTIDAE SQUALODONTIDAE DELPHINIDAE
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?
baleen ventral grooves tongue jaw DIFFERENCES
feeding Feeding Humpback whales
Feeding Gray whales
Feeding Gray whales
Feeding Other whales
HOW DO YOU DETERMINE THE AGE OF A DOLPHIN AND A WHALE?
Feeding Group waiting to feed Sentinel Dolphins feeding Sentinel
How echolocation works? Returning echo Sound emission
Where is the food?
... 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
Alliances and Superalliances
Courtship & Mating
Not easily distinguishable.... female male navelanusgenital slit mammary slit
Long term bonds
Cetaceans’ sensory world Sight Smell Taste Touch Sound
Cetaceans’ sensory world SOUND Communicationwhistles Echolocationclicks
Song of a whale Dolphin whistles Cetaceans’ sensory world
Modern humans=7.06 Great apes=1.91Odontocetes=3.78 Brain and intelligence
Social learning “Culture”
Self-recognition Sponge carrying
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 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 of 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)