Cetaceans are mammals that evolved from land mammals and adapted to life in the ocean. They include whales, dolphins, and porpoises. Cetaceans have streamlined bodies for swimming, breathe air through blowholes, and use echolocation and vocalizations to communicate. While baleen whales filter feed using baleen plates, toothed whales have teeth adapted for catching prey which they swallow whole. Dolphins and porpoises are considered small toothed whales that typically travel in pods.

1. Cetaceans Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Cetacea Suborder: Mysticeti Suborder: Odontoceti Family: Delphinidae Family: Phocoenidae

2. Mammals Evolved from reptiles 200 million years ago 4,500 species Endothermic – warm-blooded Brain size far larger in proportions than other organisms Have hair, mammary glands

3. Evolution of Whales Pakicetids are reasoned to be the earliest ancestors Lived on land Closest living animals to whales are cows, hippos, and giraffes Evolved into archaeocetes More eel like form that developed into modern whales

4. Ancient Whale Ancestors

7. Cetaceans Whales, dolphins, and porpoises All are completely adapted for life in water Bodies designed for streamline swimming Breathe air

11. General Exterior Body Structure Pair of front flippers w/ similar bone structure to our hands Caudal fin end in a pair of fin-like horizontal flukes Blowhole – nostrils found on top of the body Some species missing dorsal fin

12. Flipper vs. Hand Structure

13. General Interior Body Structure Small, useless pelvic bones are the rear pair of limbs that never developed Blubber – fatty layer that provides insulation and buoyancy

14. Melon Special organ located between the blowhole and rostrum of toothed whales Oil filled sac that serves as an acoustical lens

15. Spermaceti Organ Massive melon found in sperm whales Filled with waxy oil called spermaceti Used for lanterns and candles

16. Swimming Cetaceans swim by beating their flukes up and down while maneuvering with their fins.

17. Breathing Can exhale and inhale at incredible rate Blowhole allows for breaths while swimming Spout or blow – combination of warm breath, mucus, and seawater that differs whale to whale

18. Diving Adaptations Cetaceans hold breath for 15-30 seconds, then quickly take a breath to maximize oxygen consumption Blood has higher concentration of red blood cells which can hold more hemoglobin Reduce heart rate when diving Divert blood to vital organs Collapsible lungs prevent the nitrogen from dissolving in blood and thus getting the bends

19. Echolocation Nature’s version of sonar Animals release sound waves which create echoes which are analyzed by brain Created by the passage of air inside cetaceans Melon focuses the sound waves

20. Vocalizations Play an important role in communication Unique sounds for each species Used for all forms of communication Humpback whale songs are used for attracting mates Whale Songs

21. Baleen Whales - Mysticeti “ toothless” whales Baleen – rows of flexible, fibrous plates that hang from the upper jaw Made of the same material as hair and nails Covered with bristles Filter water through and lick what has been left behind

22. Baleen Structure

23. Rorquals Lower part of the throat expands when filtering food Includes humpback and blue whale

25. Other Baleen Feeding Methods Some whales skim the surface These ones have the largest plates with the finest bristles Others are bottom feeders who stir up the bottom and then filter

26. Toothed Whales Teeth adapted for a diet of fish, squid, and other prey Use teeth to catch and hold not to chew, rather it is swallowed whole Ambergris – remnants of indigestible food and debris that accumulates as sticky globs, used for perfume

28. Dolphins & Porpoises Considered whales Technically porpoises only consist of a small group of blunt-nosed whales

29. Dolphin & Porpoises Most of the small whales called dolphins Dolphins typically have a distinctive snout called a beak Travel in large groups called pods

30. Family Delphinidae Dolphins Beak Cone-shaped teeth Curved/hooked dorsal fin Included Killer Whale 32 species

32. Family Phocoenidae Porpoises Smaller than dolphins Small triangular dorsal fins No beak Small spade shaped teeth Travel in smaller groups 6 species

33. Porpoise vs. Dolphin