Marine Bio: Thermodynamic

Mammals

  • endothermic and homeothermic

  • Challenge: heat loss

HL=SA*C*(Tbody-Twater)

  • SA surface area (m2)

  • C thermal conductance

  • T temperature

Heat Loss is greatest when

  • high SA to vol ratio

    • problem: small body size

  • Body surface conducts heat well

    • problem: need additional insulation

  • Large difference b/w internal body temp and water temp

Reducing Heat loss

  • Large body size

    • reduce SA/ vol.

  • Reduce conductance (increase insulation)

  • Reduce difference b/w water temp and exposed tissue

  • Increase metabolic rate?

Increasing Body size (reducing SA)

  • Bergman’s rule

    • animals within a specific group tend to be larger as latitude increases

    • Poles will have a larger latitude than the equator (0 degrees)

      • animals will get larger as they closer to the poles

  • Allen’s rule

    • endotherms from colder climates tend to have shorter appendages than equivalent animals from warmer climates

Reducing Conductance (increase insulation)

  • Fur vs. Blubber

    • Fur traps air

      • insulation low conduce than water

  • More highly adaptive to aquatic environment

    • less fur

    • Bulbber instead

Fur density and Blubber thickness amount Carnivores

Fur seals:

  • Stiff outer guard hairs and dense waterproof underfur

  • Moderate blubber layer

Seal Lions:

  • Single coat of hair

  • Thicker blubber layer

    • Rely only on blubber for insulation in water

Blubber as insulation:

  • Insulation value varies:

    • Lipid content

    • Thickness

Bubber

  • Multi-function tissue

    • Streamlining

    • Buoyancy

    • Insulation

    • Energy storage

Heat Loss and Young Animals

  • Young are very susceptible to heat loss

    • small body size (high SA)

    • Blubber layer thin at birth

  • Solutions:

    • Large cetaceans

      • many migrate to warm waters to breed

    • Pinnipeds

      • breed on land/ice and pups have Lanugo