1. Whales, Dolphins and Porpoises
Whales, dolphins and porpoises are cetaceans (Class Mammalia, Order Cetacea)
Of all the marine mammals, cetaceans (and sirenians) have made the most complete transition to aquatic life
Spend their entire lives in the water
The bodies of cetaceans are streamlined and look remarkably fish-like; an example of convergent evolution

2. Convergent Evolution: Streamlining
Convergent evolution is the process by which unrelated species evolve similar physical characteristics because they have similar lifestyles

3. Convergent Evolution

4. Whales, Dolphins, and Porpoises
Cetaceans have a pair of front flippers, but the rear pair of limbs has virtually disappeared
Remain in adults as small, useless bones
Most cetaceans have a dorsal fin, like fishes
Their muscular tail ends in a pair of fin-like, horizontal flukes

5. Whales, Dolphins, and Porpoises
Blubber provides cetaceans with insulation
Cetacean nostrils are on top of the head, forming a single, or double opening called the blowhole

6. Whales, Dolphins and Porpoises
There are ~90 species of cetaceans
All are marine, except for 5 species of freshwater dolphins
Cetaceans are divided into two groups:
Toothed whales – includes dolphins & porpoises
Baleen whales; toothless, filter-feeding whales
Photos property of the Riverhead Foundation

9. Cetaceans: Toothed Whales
The majority of cetaceans are toothed whales
Toothed whales use their teeth only to catch and hold prey, not to chew it
Toothed whales have a single blowhole (one opening) on the top of their head
Though they are all whales, most of the small toothed whales are called dolphins or porpoises
Photo property of the Riverhead Foundation

10. Is it a dolphin or a porpoise?
The six species of porpoises are blunt-nosed whales, having flattened teeth
The many more species of dolphins possess a distinctive snout or ‘beak’ and have conical teeth
Porpoise
(Family Phocenidae)
Dolphin
(Family Delphinidae)

11. The Toothed Whale Whales
The toothed “whales” include the sperm whale, beluga, pilot whales, beaked whales, and orca, each divided into their own families

12. A bottlenose whale? Yes!

13. Orca: The Killer Dolphin?

16. Echolocation All species of toothed whales are capable of echolocation
Marine mammals echolocate by emitting sound waves, and listen for the echoes reflected back from surrounding objects
The brain then analyzes the echoes
The time it takes the echoes to return tells the animal how far away the object is
A type of biological sonar!

17. Echolocation

19. Baleen Whales Toothless whales are best known as baleen whales
Instead of teeth, they have rows of flexible plates, or baleen, which hang down from the upper jaws
Baleen is made of keratin
The inner edge of each plate consists of hair-like bristles that overlap and form a dense mat

20. Baleen whales

21. Baleen Whales

22. Baleen Whales
Baleen whales are characterized not only by their baleen, but by the double opening of their blowholes (double blowhole)
Baleen whales can be further divided into the rorquals; rorquals feed by gulping up schools of fish and swarms of krill
The lower portion of the throat expands during feeding, along distinctive grooves
Photo property of the Riverhead Foundation

23. Baleen Whales: the Rorquals
Photos property of the Riverhead Foundation

24. Baleen whales are the largest of all whales and the largest of all animals ever to have lived on earth
Photo property of the Riverhead Foundation

26. Most of the 13 species of baleen whales are endangered from centuries of hunting/whaling

27. Save the Whales!
The great baleen whales have been hunted for several centuries for their meat and blubber which was processed into fuel, soaps and other products
Many populations were decimated (and some have still not recovered)
The North Atlantic Right Whale was most dramatically affected; only ~330 individuals remain!!!

28. Save the Whales!
International Whaling Commission banned whaling in 1986, however some countries continue hunting for “scientific purposes”
Current Japanese quotas allow for the take of 935 minke, 50 fin and 50 humpback whales
Very controversial
4:28

29. So long and thanks for all the fish!