### animal | vertebrate | mammal | aquatic mammal:

Cetacean
* All cetaceans are social animals
  - warm-blooded, meaning they regulate their own body temperatures
* Many cetaceans can dive for extended periods of time to great depths
  - long periods and to great depths
* Most cetaceans have a prominent upper jaw in front of the eyes
  - swim faster under water
* Some cetaceans are the only animals other than elephants that have a brain larger than man's
  - grow to be very large
  - seem to enjoy human music
  - spend their lives in freshwater rivers and lakes
* also lack hair as adults.
* appear to possess self-awareness.
* are aquatic mammals
  - conscious breathers
  - found in all oceans
  - generally uncommon except along the edges of the region where deeper waters are found
  - great divers
  - highly intelligent mammals
  - just big fish to many Caribbean fishers
* are mammals live completely in the water
  - that live their entire lives in the water
* are mammals, but they only have a few hairs on their bodies
  - who through evolution returned back to the water from land
* are marine mammals that are well-adapted for living in water
  - with a torpedo-shaped, virtually hairless, body
  - noted for their play behavior, seemingly pleasurable activities with no serious goal
  - ocean mammals, including whales and dolphins
  - placental mammals
  - sea mammals
* are the group of mammals that includes the whales, dolphins, and porpoises
  - only animals other than the elephant to have a brain larger than a human
  - order of marine mammals that includes all whales, dolphins and porpoises
  - truly the caretakers of the Earth
  - two to three times as efficient at removing oxygen from inhaled air
  - warm blooded, air breathing mammals
* can be enormous, like the blue whale, or tiny, like some species of porpoise.
* comprise all whales, porpoises, and dolphins.
* differ greatly in their appearance, distribution, and behavior.
* have an enigmatic evolutionary history of re-invading aquatic habitats
  - hair on their snouts as a fetus
  - long torpedo-shaped bodies and tails that end in flukes
  - lungs and come to the surface to breathe air, like other mammals and unlike fish
  - lungs, meaning they breathe air
  - many unique features
  - powerful hearts
  - similar penises
  - the advantage of having the blowhole on top of the head
* is an aquatic mammal
* live in all of the oceans and many of the major rivers of the world
  - the sea with other groups of animals and they can reach large dimensions
* live, breed, rest, and carry out all of their life functions in the water.
* never leave the water, even to give birth.
* show less definitive behavior of self-awareness, because they have no pointing ability.
* spend their lives in the wayer, some live in family groups called pods
  - whole lives in water and even give birth there
* swim by moving their flukes up and down in the water.
* tend to live in social groups and have relatively large brains.
* use blowholes, still another mechanism, to produce controlled vocalization
  - the total geomagnetic field of the Earth as a map
* usually bear one calf
  - initiate expiration prior to the blowholes breaking the surface