Ziphius cavirostris Cuviers Beaked Whale 16 23 feet in length 5500 lbs Marine Bio Conservation Society 2013 Hypothesis Bottlenose dolphins have a caval sphincter to prevent high pressure blood from returning to the heart during a dive to depth ID: 584845
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Slide1
138 minutes!Slide2
Ziphius
cavirostris
Cuvier’s Beaked Whale
16 – 23 feet in length
5,500 lbs. (Marine Bio Conservation Society, 2013)Slide3
Hypothesis - Bottlenose dolphins have a caval sphincter to prevent high pressure blood from returning to the heart during a dive to depth.
Prediction - If bottlenose dolphins have a
caval
sphincter, then the region of the diaphragm surrounding the vena cava will have a greater proportion of slow-twitch fibers than the costal region.Slide4
The Problems with DivingCan’t replenish oxygen stores – can’t breathePressureIncreases by 1 atm for every 10 m (33 ft
) depth
Thermoregulation
Colder at depthSlide5
Diving Adaptations in CetaceansReduce oxygen use (Ridgway, 1972)Bradycardia - slowing of heart rate
Peripheral vasoconstriction - sends blood to brain and heart
Utilize gliding (Williams et al., 1999)
Elsner
(1998)Slide6
Diving Adaptations in CetaceansOxygen stores – scuba tank (Ridgway, 1972)Relatively larger blood volumeIncreased myoglobin concentration in musclesSlide7
Diving Adaptations in CetaceansPressure (Ridgway, 1972)Flexible thoraxLarge veins, venous sinuses, and rete mirabilia
Caval
sphincter
Cotten
et al. (2008)Slide8
Cotten
et al. (2008) and Dearolf (2002)Slide9
Dearolf (2002)Slide10
Dearolf (2002)
Vena cava
Esophagus
Dorsal aorta
DiaphragmSlide11
Harrison and Tomlinson (1955)
Vena cava
Diaphragm
Caval
sphincterSlide12
Properties of SphinctersLarge proportions of slow twitch fibers (Cobb et al., 1994)
Costal Diaphragm
Esophageal
SphincterSlide13
Slow-twitch
long contraction times
fatigue-resistant
aerobic
Fast-twitch
short contraction times
fatiguable
anaerobic
Slow- and Fast-Twitch FibersSlide14
Hypothesis - Bottlenose dolphins have a caval sphincter to prevent high pressure blood from returning to the heart during a dive to depth.
Prediction - If bottlenose dolphins have a
caval
sphincter, then the region of the diaphragm surrounding the vena cava will have a greater proportion of slow-twitch fibers than the costal region.Slide15
Test Prediction – Brief MethodsHistology – staining for myosin ATPase (Hermanson and Hurley, 1990)Compare proportions of slow-twitch fibers in the costal and
caval
diaphragm of bottlenose dolphinsSlide16
Summary of Results and Conclusion(s)?Discipline dependentJournal dependent