6.11 Buoyancy and Its Regulation ....................................... 176 6.11.1 Gas Vacuole Structure ..................................................... 176 6.11.2 Pressures Acting on Gas Vesicles .................................... 176 6.11.3 Buoyancy Regulation ...................................................... 177 6.11.4 Sinking or Floating ..........................................

The modern scuba diver has become a slave of the buoyancy compensator. Throughout scuba diving history the diver has had to cope with variations in buoyancy due to suit compression and air usage. During the past five years scores of buoyancy compensation units have appeared on the market. Frequently manufacturers and instructors indicate that the buoyancy compensator is extremely useful for aid...

In southern elephant seals (Mirounga leonina), fasting- and foraging-related fluctuations in body composition are reflected by buoyancy changes. Such buoyancy changes can be monitored by measuring changes in the rate at which a seal drifts passively through the water column, i.e. when all active swimming motion ceases. Here, we present an improved knowledge-based method for detecting buoyancy c...

Astronauts' training is conventionally performed in a pool to reproduce weightlessness by exploiting buoyancy which is supposed to reduce the impact of gravity on the body. However, this training method has not been scientifically validated yet, and requires first to study the effects of underwater exposure on motor behavior. We examined the influence of neutral buoyancy on kinematic features o...

We measured the densities of the cell sap, endoplasm and cell wall of Nitellopsis obtusa and Chara corallina using interference microscopy, refractometry, immersion refractometry, equilibrium sedimentation and chemical microanalysis techniques. These values are important for the determination of many rheological properties of the cytoplasm as well as for understanding buoyancy regulation, disp...

Flying and terrestrial animals should spend energy to move while supporting their weight against gravity. On the other hand, supported by buoyancy, aquatic animals can minimize the energy cost for supporting their body weight and neutral buoyancy has been considered advantageous for aquatic animals. However, some studies suggested that aquatic animals might use non-neutral buoyancy for gliding ...

Swimming at an optimal speed is critical for breath-hold divers seeking to maximize the time they can spend foraging underwater. Theoretical studies have predicted that the optimal swim speed for an animal while transiting to and from depth is independent of buoyancy, but is dependent on drag and metabolic rate. However, this prediction has never been experimentally tested. Our study assessed t...

Recent work has produced a theory for tropical convective available potential energy (CAPE) that highlights the Clausius-Clapeyron (CC) scaling of the atmosphere’s saturation deficit as a driver of increases in CAPE with warming. Here we test this so-called “zero-buoyancy” theory for CAPE by modulating the saturation deficit of cloud-resolving simulations of radiative-convective equilibrium in ...

Buoyancy is a major determinant of locomotory cost in diving animals. As seabirds have a large amount of air in their feathers and respiratory system, they should work hard against buoyancy to descend in the water column. Since buoyancy decreases with increasing hydrostatic pressure, shallow divers, especially, should work against buoyancy during both the descent and bottom phases of their dive...