Question

1. This species is also the second deepest diver. Why is it paradoxical that the species with the largest brain on earth is such a deep diver? In your answer, include systems, tissues, cells and subcellular components involved as well as metabolic rate and homeostasis. (This question is in regards to the species the sperm whale)

2. How does this species accomplish this feat physiologically?

Answer 1

1) The Sperm whale is the second deepest diver after cuvier's beaked whale and has the largest brain of any animal in the planet. The sperm whales repeatedly dive to tremendous depth where there is extreme crushing pressure as compared to the surface which is enough to completely compress the air in the lungs. Whale's body is adapted to store oxygen in their blood and muscles, instead of keeping it in lungs. Thus sperm whale able to collapse their lungs and reduce the air pockets. At that great depth, oxygen utilization is a key factor. The sperm whale has the largest brain having larger and more number of neurons, so amount of oxygen required will be maximum for optimum nutrients. So there is self contradiction that species like sperm whale with the largest brain on earth is such a deep diver. This is because at that high crushing pressure of 1000m deep, it can shrink the air in the lungs resulting its collapse. Due to this, no more gas will enter the blood from where it would be carried to vital organs like brain, kidneys, etc. Sperm whales also tend to lower their heart rate so that oxygen consumption and utilization by different organs like brain, heart etc gets minimized. Thus in a way it contradicts the above fact of having largest brain associated with deep diving. But certain physiological adaptations of sperm whale meets this requirement as they stop their breathing and shunt blood flow from their extremitiesto the brain, heart and muscles. They also shut down digestion, kidney and liver functions.

2) The physiological adaptations of sperm whales to accomplish the deep dive includes certain changes or modifications required to sustain at such a great depth. Sperm whale lowers the heart rate associated with cardiovascular dive response resulting in decrease of heart rate than normal resting value as compared at the sea surface. The slower hesrt rates during dive, decreases oxygen delivery to tissues thereby slowing the overall depletion of blood oxygen stores and also decrease oxygen consumption by the heart itself. Sperm whales contain a muscle protein called myoglobin that stores oxygen and is ten times more concentrated in the muscles of diving animals as compared to humans. They store oxygen in their blood and muscles and also have a high blood to body volume ratio. On certain occasions, sperm whales can stop their breathing and shunt blood flow from their extremitiesto the brain, heart and muscles. They also shut down digestion, kidney and liver functions.