Order Cetacea

Cetacea Fossil evidence suggests that cetaceans share a common ancestor with land-dwelling mammals that began living in marine environments around 50 million years ago.

Characteristics The forelimbs are modified into flippers The tiny hindlimbs are vestigial they do not attach to the backbone and are hidden within the body The tail has horizontal flukes Nearly hairless Insulated from the cooler water they inhabit by a thick layer of blubber

Cetacea Cetaceans breathe air. They surface periodically to exhale carbon dioxide and inhale a fresh supply of oxygen Myoglobin, by nature, has a higher oxygen affinity than hemoglobin. The higher the myoglobin concentration in skeletal muscle, the longer the animal can stay underwater. white rabbits have 0.08 grams northern bottlenose whale has 6.34 grams

Cetacea Increased body size also increases maximum dive duration. Greater body size implies increased muscle mass and increased oxygen stores. Cetaceans also obey Kleiber's law, which states that mass and metabolic rate are inversely related, i.e., larger animals consume less oxygen than smaller animals per unit mass.

Sub Orders Suborder Odontoceti: Suborder Mysticeti: sperm whale, beluga, dolphins and porpoises, have teeth they use for catching fish, squid or other marine life they do not chew, but swallow prey whole Suborder Mysticeti: blue, humpback, bowhead and minke whales have baleen plates these plates filter small animals (such as krill and fish) from the seawater

Odontoceti http://www.youtube.com/watch?v=bwhoLlu8D_g

Mysticeti