January 19, 2016

spermwhale pottwalParāoa means in Maori language Spermwhale. (Maori = indigenes people of New Zealand)

To the indigenous Maori of New Zealand, the Parāoa or spermwhale has a deep cultural connection and is seen as a holy animal.

My reverence for this mammal has been inspired by their performance in the search for their favorite food – the giant squid, who lives in the darkest and coldest realms of deep ocean. The Parāoa is the true champion of freediving with extraordinary two thousand meter deep dives and one and a half hour long breath holds – really trivialising human capabilities!

Here some data and facts about this mammal :

  • scientific name : physeter macrocephalus
  • females grow up to 15 meters, weighing 25 tons and males grow up to 25 meters coming in at 45 tons
  • deepest recorded dive : 2250 meters in one hour and 13 minutes
  • biggest brain on earth (up to 9 kg)
  • longest intestines on earth (200 meter)
  • heart size up to 1 m³
  • males live up to 70 years and up to 100 years for whale cows
  • current population approximately 360 000
  • has the strongest sonar system in the animal kingdom and has the loudest sound produced by any animal on earth

For interested people, the physiology of the spermwhale more in detail :

The head of the whale contains a liquid wax called spermaceti from which he got his name (in German language the whale got his name because of his pot shaped head, Pottwal). This head makes approximately 1/4 of his body size and 1/3 of his body weight. Spermaceti oil was originally mistaken by the people in the middle age as the whale’s semen, because the wax part of the oil in contact with cold water crystallizes and turns white in color. People used to believe, that the head was used for reproduction and that was finally the reason for its name, which endures to this day.

Spermaceti was used mainly for the production of high-quality, brightly burning and non-smoky candles, such candles were known to be the best quality. As one “Candela” was originally defined in England the intensity of a spermaceti candle, which consumed 7.77 gram spermaceti in an hour. Even as a lubricant for precision instruments, and to engines and automatic transmission oils, it was highly appreciated. In addition, it was also used as a raw material for cosmetics and pharmaceuticals.

Each whale’s head has their own asymmetry of his head. The blowholes are not in the crest center, they are on the left front of the outer edge of the head. The paired nose opening is connected with two nose gears, the left one is crossing through the whole spermaceti organ almost straight, the right nose gear on the other hand is expanded to a curvy and shallow channel. Just for breathing this construction looks too complicated. Consequently, this gave speculations for another function.

Spermwhales are able to waylay motionless on the sea floor, waiting for approaching squid, but dead spermwhales floating on the surface. Consequently they have to make themselves heavier while descending. This complicated function is taking over the spermaceti organ, which extends over the whole head.

The function is the following :

The left nose gear will flooded with seawater, for diving it is expendable. A ring muscle (musculus maxillonasalis) is closing the entrance of trachea and lung. The whale is using the same principles for the right and curvy nose gear like a submarine, which is flooding his tanks, in this case its spermaceti organ with water for descending, and pressing the water out for ascending.

The only difference to the submarine is that the whale is cooling down at the same time as the spermaceti. In this process the wax content of the sperm oil crystallizes out. The weight proportion of wax is about one third of the sperm oil and is above 21 degree Celsius liquid and below 18 degree Celsius crystalline solid.

This difference means that the cooled down and crystallized spermaceti organ takes 2.2% less volume than the liquid one. In the solid state, and this is important, it gets a higher density. This means the whale can so alter its specific weight in order to reach great depth or to resurface with very little exertion. The whole process of crystallization is accelerated by the shutdown of the blood circulation.

On the assumed size of a sperm whale cow of 25 tons, of which is about 2.5 tons of spermaceti. After the exhalation, the animal is in the hover (plus minus zero). After the transition of the spermaceti to the crystalline form and the associated change in specific gravity of the spermaceti organ, the conditions are not present any longer. The increase in head weight makes the whale negatively buoyant, causing an initial descent rate from 1.5 to 2.2 meter per second which can be directly observed during the plunge when the animal raises the fluke in the air and then starts diving vertically. The descent occurs nearly without active swimming movement and consequently with very little oxygen consumption.

The deeper the whale dives, the more solid and dense the spermaceti becomes, because it is getting colder in greater depth and the pressure is increasing. The whale becomes more and more heavy and is able to descend faster. If the whale wants to ascend, they just empty their right nose gear and links up the blood circulation. This warmes up the spermaceti cushion; the process reverses and the animal returns with very little effort back to the surface.

After 60-70 breaths (10-15 min), they are able to dive again. Spermwhales are able to exchange 80-90% of their lung volume in one breath, not like humans with 10-15%! As a result of this he can re-oxygenate his body very quickly. Spermwhales always dive exhaled, so they avoid the Caissonsche disease. In relation to their body the lungs are very small. In order to meet the oxygen requirement for immersion times of over an hour, the whales developed special adaptation methods.

The whale has a higher content of hemoglobin between 39%-45%, compare to land mammals which is between 30-34%, so they can uptake a greater amount of oxygen faster. The amount of blood in relation to the body weight is quite small. The whale has a blood volume of 3,9% of his body weight, a land mammal has 10-13%. However we must not forget, that the whale fat layer makes up a large part of the weight. Whale blubber and spermaceti can absorb oxygen up to seven times more than water, so it is a very good oxygen facility. More detailed facts about this mechanism are unknown at the moment.

The most significant oxygen storage represents the myoglobin. Similar to hemoglobin in the blood, myoglobin is a muscle protein which binds oxygen. The whale has 8 to 9 times as much myoglobin in the muscle than found in a land mammal. Whale meat is dark red, nearly black, which is due to the extremely high density of myoglobin in the muscles. Actually, this high amount of the protein would orinarily clump together and therefore be dysfunctional, but obviously after 50 million years evolving within the whale, that is just not the case. The reason is found in the protein itself. For all record divers the electrical charge on the surface of the protein is higher than that of their non-diving relatives. The electrically charged surface makes the myoglobin molecules keep distance from each other, even if they occur in unusual concentration.

The whale incorporates 40% more oxygen than humans. For Spermwhales it’s not like humans where a high level of CO2 gives the stimulus to breath, but the oxygen deficit.

When the whale starts diving, all organs that are not needed, can be disconnected by the presence of constricting sphincter muscles in the venous blood vessels.

Like some other mammals, the heart rate drops drastically at the beginning of the dive.

During the dive, only brain, heart, spinal cord and a part of the muscles are supplied with oxygen. The rete mirable, a sponge-like complex of arteries and veins very close to each other, take up a great amount of blood acting as an oxygen store.

A further ability of the whale to go easy with oxygen is that the muscles are temporarily deprived during the dive, however this is only in extreme situations. By anaerobiosis glycogen instead of oxygen is used to fuel the muscles. This causes lactic acid, which remains in the muscles until after re-surfacing, unlike in humans where it is released straight into the bloodstream.

The spermaceti organ has another important function. It acts as a focusing apparatus for the whales sense of echo-location and a resonator. This makes it possible for the whale to sense the motion of its prey better as well as its position. The changing distance to the prey affects the time interval between the returning clicks reflected by the prey (doppler effect). This explains the high density and compressibility of the spermaceti, which enhance the resonance by the contrast of the acoustic properties of the sea water and of the hard tissue surrounding the spermaceti.