New research published Monday in Proceedings of the National Academy of Sciences is the first to provide a heart rate profile for free-ranging blue whales. The resulting data shows how the hearts of these enormous cetaceans help them hold their breath for prolonged periods of time as well as how they’re suddenly able to exert the energy needed for lunge feeding and then replenish their blood oxygen levels when back at the surface.
At the same time, the new study, co-authored by marine biologist Jeremy Goldbogen from the School of Humanities Sciences at Stanford University, suggests the blue whale has reached the largest size possible for an aquatic organism on Earth. The cardiovascular system of the blue whale, while impressive, is probably the limit of what is biologically possible, according to the new research.
Blue whales are the largest creatures to have ever lived on the planet. These aquatic mammals can reach upwards of 30 meters (98 feet) in length and weigh an astonishing 173 metric tons (380,000 pounds or 172,365 kilograms). To put this into perspective, that’s equal to about 292 very heavy African elephants—currently the largest terrestrial animal on Earth.
Living in the ocean is what allow blue whales to grow to such an enormous size possible, as no creature of that immensity could possibly support itself on land. The largest land animals to have ever lived were the titanosaurs, a group of four-legged, long-necked dinosaurs that included Argentinosaurus, Brontosaurus, and Rapetosaurus. These herbivores got as long as 15 meters (50 feet) and weighed nearly 82 metric tons (180,780 pounds or 82,000 kilograms). They were big, no doubt about it, but not nearly as big as the blue whale.>br>
The new research notes that another important factor allowing blue whales to grow so large is their highly specialized cardiovascular system. For marine biologists, however, understanding exactly what makes the blue whale’s heart tick has proven difficult given they’re almost too big to measure. To overcome this hurdle, Goldbogen and his colleagues developed an electrocardiogram (ECG) tag that they attached to a blue whale with suction cups.
[---]
The heart rate profile for the blue whale came as a surprise even to the researchers. The observed bradycardia was 30 to 50 times lower than expected. The low rate was made possible by an elastic-like part of the whale’s body called an aortic arch, according to the new paper. This remarkable piece of whale anatomy transports blood to the outer reaches of the whale’s gigantic body, contracting slowly to maintain blood flow during the long interval between beats. The heart’s unique pulsations and shape keeps blood flowing and is what makes the whale’s higher heart rate possible.
During tachycardia, the blue whale’s heart rate is likely working at the highest maximum limit allowable by the constraints of biology, according to the authors. A more robust cardiovascular system is not likely, they argue, and the new research may actually explain why no species on Earth has grown bigger than the blue whale.
- More Here
At the same time, the new study, co-authored by marine biologist Jeremy Goldbogen from the School of Humanities Sciences at Stanford University, suggests the blue whale has reached the largest size possible for an aquatic organism on Earth. The cardiovascular system of the blue whale, while impressive, is probably the limit of what is biologically possible, according to the new research.
Blue whales are the largest creatures to have ever lived on the planet. These aquatic mammals can reach upwards of 30 meters (98 feet) in length and weigh an astonishing 173 metric tons (380,000 pounds or 172,365 kilograms). To put this into perspective, that’s equal to about 292 very heavy African elephants—currently the largest terrestrial animal on Earth.
Living in the ocean is what allow blue whales to grow to such an enormous size possible, as no creature of that immensity could possibly support itself on land. The largest land animals to have ever lived were the titanosaurs, a group of four-legged, long-necked dinosaurs that included Argentinosaurus, Brontosaurus, and Rapetosaurus. These herbivores got as long as 15 meters (50 feet) and weighed nearly 82 metric tons (180,780 pounds or 82,000 kilograms). They were big, no doubt about it, but not nearly as big as the blue whale.>br>
The new research notes that another important factor allowing blue whales to grow so large is their highly specialized cardiovascular system. For marine biologists, however, understanding exactly what makes the blue whale’s heart tick has proven difficult given they’re almost too big to measure. To overcome this hurdle, Goldbogen and his colleagues developed an electrocardiogram (ECG) tag that they attached to a blue whale with suction cups.
[---]
The heart rate profile for the blue whale came as a surprise even to the researchers. The observed bradycardia was 30 to 50 times lower than expected. The low rate was made possible by an elastic-like part of the whale’s body called an aortic arch, according to the new paper. This remarkable piece of whale anatomy transports blood to the outer reaches of the whale’s gigantic body, contracting slowly to maintain blood flow during the long interval between beats. The heart’s unique pulsations and shape keeps blood flowing and is what makes the whale’s higher heart rate possible.
During tachycardia, the blue whale’s heart rate is likely working at the highest maximum limit allowable by the constraints of biology, according to the authors. A more robust cardiovascular system is not likely, they argue, and the new research may actually explain why no species on Earth has grown bigger than the blue whale.
- More Here
No comments:
Post a Comment