How marine mammals stay warm

Wear a “blubber glove” and plunge your hand into an ice water bath to investigate the insulative properties of blubber.

Please find a printable PDF of this activity here.


  • Blubber is important for most marine mammals, such as whales and seals. The thick layer of fat provides insulation from cold ocean temperatures.
  • Blubber is also important because it stores energy that can be broken down to provide the animal energy when food is unavailable.
  • Weddell seals live in Antarctica and can have more than 2 inches of blubber. Considering their massive weight of 400-600 kg (880-1320 lbs), that could be up to 240 kg (530 lbs) of pure blubber.
  • Bowhead whales live in Arctic waters and can have 43-50 cm (17-20 inches) of blubber, thicker than any other whale's blubber layer.


  • 3 gallon or quart size zippered plastic bags
  • 1 large container of lard or shortening
  • Heavy tape
  • 2 large containers of ice or ice water
  • Optional: Heavy rubber kitchen glove


  • Scoop fat into two of the zippered plastic bags. Spread the fat inside the bag so that it fills the bag and is about 1 inch thick. Seal the bags.
  • Lay one bag on top of the other and tape three of the sides together making a “mitten."
  • Slide the mitten into the third bag with the open side of the mitten facing out of the third bag.
  • Put the mitten into one of the containers of ice, or ice water.
  • Put one hand into the mitten and put your bare hand into the second container of ice.
  • Optional: Use a heavy rubber kitchen glove can for the bare hand. If a lot of people are doing the activity this will help keep the demonstration area dry.


  • Use a thermometer to measure the temperatures over time, with and without the mitten, and graph the results.
  • Predict results and test mittens with different thicknesses of fat.
  • Predict results and test mittens with different materials for insulators.
  • Investigate the thickness of different marine mammals blubber and make models showing the actual thicknesses.

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