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Questions and Answers
Dives by Weddell seals are mostly
Dives by Weddell seals are mostly
Which animal is the deepest diver?
Which animal is the deepest diver?
An animal's maximum possible blood store of O2 is calculated by
An animal's maximum possible blood store of O2 is calculated by
One of the most consistent features of diving species of mammals is that, relative to terrestrial species, they have
One of the most consistent features of diving species of mammals is that, relative to terrestrial species, they have
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In diving mammals, the thorax
In diving mammals, the thorax
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Which oxygen store (per kg) is significantly larger in true (phocid) seals, such as the Weddell seal, compared to a human?
Which oxygen store (per kg) is significantly larger in true (phocid) seals, such as the Weddell seal, compared to a human?
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Which oxygen storage compartment tends to be the largest in diving mammals?
Which oxygen storage compartment tends to be the largest in diving mammals?
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The predicted dive time of a Weddell seal based on calculations of its oxygen stores is likely to be
The predicted dive time of a Weddell seal based on calculations of its oxygen stores is likely to be
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Which statement regarding circulation and diving is false?
Which statement regarding circulation and diving is false?
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Because of a regional vasoconstriction during a prolonged dive, the heart responds with a reduction in
Because of a regional vasoconstriction during a prolonged dive, the heart responds with a reduction in
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In freely diving marine mammals, heart rate
In freely diving marine mammals, heart rate
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Fish removed from water are likely to exhibit
Fish removed from water are likely to exhibit
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During forced submergence, harbor seals deplete O₂ in their ______ while O₂ levels in their ______ remain high.
During forced submergence, harbor seals deplete O₂ in their ______ while O₂ levels in their ______ remain high.
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Metabolic limits on dive duration are determined by all of the following except
Metabolic limits on dive duration are determined by all of the following except
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During a voluntary dive, a Weddell seal's metabolic rate is ______ that of a resting seal on land.
During a voluntary dive, a Weddell seal's metabolic rate is ______ that of a resting seal on land.
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During a dive, blood pH tends to ______ due to an increase in ______ .
During a dive, blood pH tends to ______ due to an increase in ______ .
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The longest dive that can be undertaken without a net accumulation of lactic acid above resting level is called the
The longest dive that can be undertaken without a net accumulation of lactic acid above resting level is called the
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What is the primary cause of decompression sickness?
What is the primary cause of decompression sickness?
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The deepest dives of Weddell seals are at a depth of about _______ m.
The deepest dives of Weddell seals are at a depth of about _______ m.
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Following a 45-minute dive by a Weddell seal, circulating levels of lactic acid would likely fall to pre-dive levels after about ______.
Following a 45-minute dive by a Weddell seal, circulating levels of lactic acid would likely fall to pre-dive levels after about ______.
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Study Notes
Diving Mammals and Conditions
- Diving mammals avoid "the bends" by alveolar collapse, a crucial area for research.
- Sequestering oxygen in lungs during deep dives has both advantages and disadvantages.
- A disadvantage is oxygen not being available for the dive, however, the possibility of preventing decompression sickness due to slowing/stopping nitrogen during diffusion is a positive outcome. During ascent, alveoli opening allows resumption of diffusion for continued oxygen use.
Weddell Seal Diving
- Weddell seals primarily conduct short, shallow dives.
- Their deepest dives are approximately 600 m deep.
Deepest Diver
- Weddell seals are the deepest divers among the listed animals (fur, elephant, crabeater seals).
Blood Oxygen Storage for Divers
- Maximum blood oxygen storage is calculated by multiplying the oxygen-carrying capacity of the blood by blood volume.
Consistent Diving Mammal Feature
- Diving mammals have high myoglobin concentrations in their skeletal muscle, contrasted with terrestrial species.
Diving Mammal Thorax
- Diving mammals have a freely compressible thorax, which is in contrast to rigid thoraxes in other species and depths.
- This is used in varying degrees dependent on the species.
Oxygen Stores in Diving Mammals
- In true seals, O2 bound to myoglobin and hemoglobin is a larger oxygen store (per kilogram) compared to humans.
Largest Oxygen Storage Compartment
- Lungs are typically the largest oxygen storage compartment in diving mammals.
Predicted Dive Times and Weddell Seals
- Predicted dive times for Weddell seals using oxygen storage calculations tend to be shorter than actual maximal dives found in the wild.
Regional Vasoconstriction and Diving
- Regional vasoconstriction during a prolonged dive reduces cardiac output and heart rate.
- This is a critical part when considering circulatory adjustments during dives.
Freely Diving Marine Mammals
- In freely diving marine mammals, the heart rate decreases in a graded manner with dive duration.
Fish Removed from Water
- Fish removed from water typically exhibit profound bradycardia.
Harbor Seals During Forced Submergence
- During forced submergence, harbor seals deplete oxygen in their muscles while blood oxygen levels remain high.
Weddell Seal Lactate Levels Post-Dive
- Circulating lactate levels in Weddell seals fall to pre-dive levels approximately 70 minutes after a 45-minute dive.
Dive Duration Limits
- Dive durations are restricted by oxygen stores, oxygen usage rates and lactic acid production.
Weddell Seal Metabolic Rate during Dive
- Weddell seal's metabolic rate during voluntary dives is lower than a resting seal on land.
Blood pH During Dives
- During dives, blood pH decreases due to increased carbon dioxide and lactic acid.
Aerobic Dive Limit
- The longest dive without a net accumulation of lactic acid above resting level is the aerobic dive limit.
Primary Cause of Decompression Sickness
- The primary cause of decompression sickness is the formation of nitrogen bubbles in the blood.
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Description
Explore the fascinating adaptations of diving mammals, including their methods for avoiding decompression sickness and their unique oxygen storage capabilities. The quiz highlights the diving patterns of Weddell seals and their incredible depth records compared to other species. Test your knowledge on the physiological strategies that enable these mammals to thrive in deep waters.
