Chapter 4 - Weight and Density of Water

Notes for Chapter 5:
Adaptations to the Weight and Density of Water

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Case History: Heads Up in the Mesozoic Seas

    Featured Organisms (p. 106):
        Ctenochasma (pterosaur, Jurassic Period, 180 Mya)
     Plesiosaurs
    RQ 5.1: Could you distinguish between some possible versus
    unlikely modes of feeding in Ctenochasma or a plesiosaur?

I. Buoyancy, Streamlining, and Drag: Coping with Water
Density and Viscosity

    a) The Control of Buoyancy
        1) Many organisms neutralize their buoyancy by maintaining
            lightweight body fluids.
        terms: neutrally buoyant

         Featured organisms (p. 108, Fig. 5.1):
       Siphonophores (colonial jellyfishes)
       Chambered nautilus (Nautilus)
       Cuttlefish (Sepia)
       Ray-finned fishes (teleosts and relatives)

RQ 5.2: How does each of the above featured organisms solve
the problem of maintaining neutral buoyancy?

        2) Bubbles, swim bladders, and other gas-filled spaces provide
            lots of lift, a few hazards.
        terms: swim bladder, gas gland, rete mirabile [link dead? 3/13/01], oval organ

RQ 5.3: What is at least one advantage and one disadvantage of
the gas-filled space solution to maintaining buoyancy?

RQ 5.4: Describe the alternative use of a gas gland versus an
oval organ in a teleost fish.

3) Risk-management strategies by fishes include no swim
bladders, oil-filled swim bladders, and other options.

   RQ 5.5: Contrast buoyancy-control in a fish like a shark, whose
    ancestors never had a swim bladder, with that of a skipjack tuna,
    whose more ancient ancestors had a swim bladder? Why would
    a tuna benefit from "giving up" a functional swim bladder?

4) Giant living hot-oil balloon?
terms: spermaceti (whalers made into candles), spermaceti organ

Featured organism (p. 111): sperm whale

    RQ 5.6: Explain how a sperm whale uses its circulation system
    in contact with its spermaceti oil to either help it sink to deep
    "hunting" depths or rise back up to the surface for air.

    b) Movement, Streamlining, and Speed
        1) Large streamlined animals create little turbulence and
            can swim rapidly.

        2) Water viscosity prevents small swimmers from going
            fast - and retards their sinking.
        terms: surface-to-volume (S/V) ratio, surface area, body volume

         Featured Organisms (p. 113, Fig. 5.5):
           Arrowworm (chaetognath, 6mm length)
           Saury (predatory fish, 30cm or 300mm length)

RQ 5.7: Briefly contrast the problems faced by a tiny chaetognath
(high S/V ratio) with a much larger saury (low S/V ratio).

II. Pressure and the Depth of the Oceans
terms: atmospheric pressure, lb. of force, 1 atmosphere (atm),
1 pascal

a) The Effect of Pressure on Enzymes and Metabolic Rates

1) Pressure changes the rates at which enzymes operate.

2) Some enzymes of deep-living animals are not affected
by pressure change.

3) Are most deep-sea bacteria inhibited by high pressure?

        RQ 5.8: When the submersible, Alvin, accidentally sunk in
        1968, why were the crews’ lunches still edible after being
        submerged for 10 months?

4) To avoid death by pressure, stay at one depth.

    b) The Distortion of Organisms with Gas-Filled Spaces in their
        Bodies
         Featured organism (p. 118): Tuffy-the-dolphin

        RQ 5.9: What happens if a scuba diver in a swimming pool
        blows up a balloon, ties it off, and then lets go? Why?
        What happened to a container of eggs that Jacques Piccard
        had attached to the outside of his submersible, Trieste, during
        his deep dive? Why?

c) Bends - the Result of Rapid Release of Pressure
terms: bends

         Featured organisms (deep divers, p. 119):
           Weddell seal or links: 1 - 2
           Elephant seal
           Sperm whales
           Emperor penguins

d) The Difficulty of Studying Pressure Effects

III. Life on Land and Life in the Sea

RQ 5.10 (Fig. 5.8): What are five ways that sea and land
animals differ?

a) Liberation from the Force of Gravity
Featured organism (p. 120): crab, Cancer productus

b) Life in Three Dimensions

c) Suspension Feeding: Common in the Sea, Absent on Land

d) Ectothermy in Cold Water

e) Bioluminescence in Dark Water

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