John Kanwisher

Respiration and Deep Diving in the Bottlenose Porpoise

A bottlenose porpoise was trained to dive untethered in the open ocean and to exhale into an underwater collecting funnel before surfacing from prescribed depths down to 300 meters. The animal was also taught to hold its breath for periods up to 4 minutes at the surface and then blow in the funnel. Alveolar collapse is probably complete at around 100 meters, and little pulmonary respiratory exchange occurs below that depth. Thoracic collapse was observ visually at 10 to 50 meters and by underwater television to 300 meters.

OXYGEN BALANCE IN SOME REEF CORALS

Oxygen exchange is reported for 14 species of Florida reef corals in the dark and at different light intensities. Oxygen tension was monitored with a recording polarographic electrode. Results are given as grams of carbon fixed per square meter of coral surface per day, and compensation light intensities were given for each species. Maximum ratios of photosynthesis to respiration varied from 1.9 to 5.8. Boring, filamentous green algae living in the skeleton of Dichocoenia stokesii were not observed to change their rate of oxygen consumption from dark conditions up to 5000 footcandles of light. It is concluded that reef corals are among the most productive organisms known and that, in Florida corals, the boring green algae contribute very little indeed to this productivity. Some data are given on the light impinging on Florida reefs and the light penetrating coral skeleton. Reasons for believing boring green algae are of minor importance are given in the discussion.

Temperature and Activities of a White Shark, Carcharodon carcharias

A large (4.6 m) white shark was followed for 3.5 days while its depth, water temperature and muscle temperature were recorded by acoustic telemetry. During this time the shark moved 190 km from an area south of Montauk Point, New York to Hudson Canyon. It made a number of brief excursions to the surface and to the bottom, but usually swam in the thermocline. Muscle temperature of the shark was as much as 5 C warmer than the water, confirming that a system of large retia mirabilia in the circulatory system function as heat exchangers. The shark did not thermoregulate and muscle temperature changed slowly as water temperature changed. The warming of the muscle as the shark swam into warmer water allowed us to estimate its rate of metabolism. The rate obtained is low and despite being warm, it appears that the shark can maintain itself for more than a month on a single large meal. The implications of this for its feeding habits are discussed.

The Visceral Temperatures of Mackerel Sharks (Lamnidae)

The viscera of mako Isurus oxyrinchus and porbeagle Lamna nasus sharks are significantly warmer than the water. The large suprahepatic rete mirabile in these fish is identified as a heat exchanger which retains metabolic heat to warm the visceral organs. An argument is presented that the efficiency of heat exchange in the rete must be greater than 97% to maintain the observed tissue temperatures and that this requirement explains the large size of the rete. A venous passage with a muscular wall which runs through the suprahepatic rete could allow blood to bypass the heat exchanger, and its presence suggests a simple mechanism for controlling temperature. However, measurements of temperature by acoustic telemetry from freeswimming sharks over a 4.5-day period do not give a convincing indication that stomach temperature is altered in a manner independent of the environment.

HISTOLOGY AND METABOLISM OF FROZEN INTERTIDAL ANIMALS

1. Histology of frozen shore animals has shown large pockets of intercellular ice with consequent shrinkage and distortion of the surrounding cells.2. The Q10 drops precipitously in the region of ice formation and may be as high as 50.3. High tissue salinity without freezing decreases oxygen uptake. Thus the salinity increase that results from freezing is responsible for a large part of the high Q10.

RESPIRATION AND ANAEROBIC SURVIVAL IN SOME SEA WEED-INHABITING INVERTEBRATES

1. The water trapped by large brown sea weeds at low tide may become oxygen-free in the night or on cloudy days.2. Slow-moving, non-swimming animals living in the sea weeds all the time (like nematodes and mites) are paralyzed by the removal of oxygen from the water, but they recover from this state if the period of anaerobic stress has lasted less than approximately 16 hours at 25° C. The relationship between time of anaerobiosis and time of recovery is temperature-dependent and a characteristic of each of the three species investigated (Enoplus communis, Rhombognathides seahami, Halacarus basteri basteri).3. Agile animals, capable of leaving and repopulating the sea weeds with the tides, show a different reaction pattern. One of the amphipods investigated (Calliopius laeviusculus) did not survive even a few minutes of anaerobiosis, while the other two species (Gammarus oceanicus, Hyale prevosti) survived from about half an hour to three hours of anaerobiosis. The former species occasionally leads a pela...

Muscle temperature in free-swimming giant Atlantic bluefin tuna (Thunnus thynnus L.)

Muscle temperature was measured by telemetry in giant Atlantic bluefin tuna whilst the tuna were free-swimming in large pounds. Muscle temperature tended to remain steady at about 24 degrees C; water temperature ranged from 9 to 17 degrees C. Muscle temperature was much less variable than stomach temperature in these fish. Muscle temperature varied less than 3 degrees C whereas stomach temperature varied by as much as 14 degrees C.

TRACHEAL GAS DYNAMICS IN PUPAE OF THE CECROPIA SILKWORM

New methods have been applied to the dynamics of gas exchange in the tracheal system of pupae of the Cecropia silkworm permitting the direct observation of many features of O2, CO2, and N2 flux that had previously only been deduced from indirect evidence. This system functions so efficiently that water loss is reduced to a value which is approximately the same as that produced metabolically.This work would have been impossible without the stimulating environment provided by C. M. Williams and his students. Their generous supplying of pupae is only one of the many favors for which I am indebted.

Total Energy Balance in Salt Marsh Grasses

Leaf temperature in Spartina alternifolia and S. patens varies little from the ambient air temperature. Spartina leaves lose from 70 to 460 molecules of water for every molecule of CO2 taken out of the air. This loss of water is consistent with the hypothesis that gases move between the air and the leaf by simple diffusion. There is evidence of a lowered water potential at the evaporating surface within the leaf. See full-text article at JSTOR

Electromagnetic flow sensors

Flow sensors based on the principle of electromagnetic induction were investigated as alternatives to commonly used mechanical devices utilizing rotors and propellers. Prototype sensors were constructed showing considerable promise. Measurement accuracy in excess of 1 cm see-l seems feasible with devices suited to long term battery operation. The inertial effects and many of the reliability problems inherent in moving part devices would be overcome by USC of an electromagnetic sensor. Ocean currents have been routinely mcasured by differences in potential caused by the clcctrically conductive seawater moving through the vertical component of the Earth’s magnetic field (von Arx 1950). Blood flow in animals is also determined by electromagnetic induction, the magnetic field being produced by a coil placed next to the blood vcsscl. The method is also used industrially for monitoring flow in pipes. But the use of a locally generated field has found only occasional application in oceanography (Olson 1972; Tucker 1972; Bowden and Fairbairn 1956). The continually disappointing performance of mechanical current meters has motivated us to take an independent look at the possibilities of electromagnetic flow sensors. Here WC describe first the theory involved in the design of such a sensor. Then we show what results one can get in an actual device. Finally we discuss potential uses, such as current meters, to which this kind of flow sensor can be applied.