Great White Shark YRC9P0

v=Pk-G8g3wXOg

Marine Mammals Cetaceans Pinnipeds Sirenians Polar bear Sea otter

What’s the big deal about being an aquatic mammal?

Problem and Solutions Problem: Heat conductivity of water 25x that of air Solutions?

Solutions  Insulation Marine mammals - two forms of insulation FurBlubber

INSULATION THICKNESS (mm) INSULATION (W -1 M 2o C) Still AirDry Fur Wood Adipose Muscle Water Copper Sea otter hair, Wet Harbor porpoise blubber Spotted dolphin blubber

INSULATION THICKNESS (mm) INSULATION (W -1 M 2o C Still AirDry Fur Wood Adipose Muscle Water Copper Polar bear hair, Dry Polar bear hair, Wet

Thermal Windows Feet Flippers Dorsal fin Pectoral flippers Tailflukes

Rommel et al., ‘98

Countercurrent exchanger

Conclusions Marine mammal solutions Insulation - fur and blubber Vasculature

Thermal Problem for Male Reproductive Systems Problem: Sperm production requires lower temp Terrestrial mammal solution Scrotum or cremaster sacs

Rommel et al., ‘98

The Cetacean Solution Rommel et al., ‘92

Rommel et al., ‘98

Distance from Anus (cm) Temperature ( o C) IT WORKS!

Conclusions Marine mammal solutions Decreased surface area Insulation - fur and blubber Vasculature

Structure without function is a corpse; function sans structure is a ghost - Vogel and Wainwright, ‘69