The Anatomy of Whales
The study of the anatomy of whales is the scientific study of the structure of the whales body. So we could have described the specializations of the whales bones, muscles and organ systems but we probably would have bored you. So instead we decided to look at the function of these specialization. 
Snubfin dolphins
Why are Whales so Fast?Dolphins have been recorded at speeds of up to 55km/h, even some of the baleen whales can swim 48km/h over short distances. Water has a higher resistance than air, You can experience that when you move in the water. When you are running on the land you're much faster than when you are swimming in the water. So how can these huge whales swim so fast? Whales and dolphins have a streamlined body similar to those of fast swimming fish or, torpedos which have little water resistance. Additionally whales have a smooth skin without hair which causes less turbulences than rough skin. This saves energy which can be used either to swim faster or for other activities. How do Whales use their Fins?Whales and dolphins have one dorsal fin, two pectoral fins or flippers and one fin in the end of the tail which is called fluke. The dorsal fin and fluke don't have bones but the flippers have. Flippers are modified arms and hands and therefore consist of the same skeletal elements as they do in the human body. Whales don't have hind limbs. The accompanying bones can be found in the very small embryo but they degenerate long before birth. The fluke is responsible for propulsion. By an alternate upward and downward movement of the fluke the whale swims forward. The dorsal fin and the pectoral fins are used for stability and maneuverability. But fins are also used for a lot of other things like communication. During socializing whales often slap with their fluke or flippers on the water and on other individuals. Additionally the fluke is used for protection. If e.g. killer whales attack a group of sperm whales the sperm whales come together and build a circle with their bodies. Thereby the heads of the sperm whales are close together and the flukes are directed out of the circle towards the killer whales because it is the strongest part of the whale. The flukes are moved up and down. This is called Marguerite formation. Why Can Whales Hold their Breath Much Longer Than Humans?Cetacea (whales, dolphins and porpoises) use oxygen very carefully. There are two ways of achieving that. One is to take in more oxygen on a dive. Whales do not have bigger lungs than humans in relation to body size. But they store oxygen in their blood and muscle tissue. Therefore whales and dolphins have a greater volume of blood, a higher density of red blood cells within the blood and a much higher concentration of myoglobine in the muscles. Red blood cells and myoglobine (A hemoprotein that receives oxygen from hemoglobin and stores it in the tissues until needed ) bind oxygen. The second way is the efficient use of oxygen. During dives the heart rate is slowed down. Humans do that, too, by the way. Consequently the blood flow is decreased. Additionally blood flow to pankreas and liver which tolerate oxygen shortage is decreased to 1/20 and there is no blood flow to the intestine during the dive. Heart and brain are supplied with the same amount of blood during the dive and on the water surface. Why do Whales and Dolphins in the Polar Regions not Freeze?The conductivity is 25 times higher in water than in air. Consequently marine mammals loose their heat 25 times faster than terrestrial mammals. So why do they not freeze? Why don't we freeze in winter? Because we wear warm clothes. Whales don't wear clothes, of course, but they have up to 50cm thick fat layer under their skin which is called blubber. This layer increases the distance between the water and the body cavity.
Imagine the following: if you like to knit a pullover for your 7 years old child you probably need 8 balls of wool. If you like to knit a pullover for yourself you would need 13 balls of wool and not 16 although the pullover will be twice as big as the one of your child. That's because the volume growths faster than the surface area. So you can put a body in the pullover which is twice as big as your child's one but you don't need the double amount of wool to knit it. You need less. If the whales have a small surface related to their volume, they loose less heat. So it makes sense for them to be big.
Orca How do Whales Sweat?Whales have a countercurrent heat exchanger. A What? Countercurrent heat exchangers are mainly found in areas without blubber, the thick fat layer under the whale's skin. Areas without blubber are mainly the dorsal fin, the pectoral fins/flippers and the fluke. Arteries bring warm blood from the heart to these areas to supply them with oxygen.
Additionally the blood from the two blood vessels flows in opposite directions which makes the system more efficient because heat exchange takes place all along the way of the system. So whales and dolphins have the possibility to get rid of heat at their fins. That is how they sweat. But if the cold blood would go directly back to the body, the temperature of the whale would sink fast. To keep the body temperature constant the blood in the veins is warmed by the blood in the arteries before it returns to the heart. If the whale is hot and therefore has to loose alot of heat quite fast, the heat exchanger can be bypassed. Then the cool venous blood goes directly into the body for a short time period.
Orca on the water What are Baleens?Baleens are plates made of keratin, the same material wich builds the humans hair and finger nails. Baleens can be found in the mouth of baleen whales (mysticeti) e.g. blue whales and fin whales, where they build a feeding apparatus. Each whale has two rows of baleens attached to the gum of the upper jaw, one on the left and one on the right side. All baleen plates togehter work like a brush which filters food out of the sea water. The food gets stuck in the baleens and the water leaves through the gaps in between the baleens. The number, size, colour and shape of baleen plates depend on species. Bowhead whales have up to 400 baleens in each row which can be 4m long. the 140 baleens in each row of a gray whale reach a length of only 0.5m. Baleens grow through the whole life of the whale. Because there is a difference in the amount of food eaten between the two main seasons: summer and winter, growth zones can be found on the surface of each baleen like the annual rings of a tree. But since the baleens are continuously used only 5 or 6 growth zones stay on them. Therefore baleens are not very useful for age estimation of the whale. How do Whales Hear?Toothed whales (odontoceti), e.g. dolphins, have a different system to receive sound. Their ears are surrounded by bones and they don't have a connection to the surface of the head. They are almost isolated from the rest of the skull. What is that for? An arriving sound wave will be transferred from the water to the lower jaw! In the lower jaw is a fatty region which is called the mandibular fat. The sound crosses the mandibular fat which starts behind the teeth and extends to the ear bone. The ear bone is very thin in this region. So the sound wave goes through that bone to the middle ear and further to the inner ear of the toothed whale.
Humpback waving picture courtesy of Free Nature Pictures. What else is Different in the Skull of the Whales?The skull of cetacea (whales, dolphins and porpoises) is very different from the human skull. Whales and dolphins have a long snout which is called rostrum. The nostrils are moved to the top of the head and behind the eyes. This allows a quick gas exchange without raising the whole head out of the water. There are two blow holes in baleen whales but toothed whales have only one. In contrast to humans the respiratory tract and the food tract of whales and dolphins are completely separated. So they can not choke. Besides the different bones of the head overlap which is called telescoping. Whereas humans have different types of teeth like incisors, canines, premolars and molars all teeth of toothed whales look the same. This is called homodonty. The number of teeth is very different and depends on species. The common dolphin has more than 200 teeth, some beaked whales have only two and sperm whales have teeth only in the lower jaw. The lower jaw of baleen whales can be opened at almost 90° to the whale's body which allows e.g. fin whales and sei whales to take a big amount of water in their mouth, filter it and take in a huge quantity of food at once. As written above, the lower jaw of toothed whales has not only a function in food acquisition but also in sound reception. Where is the Testes of the Whale and How Long is the Whale's Penis?The testes and the penis are hidden in the body close to the belly. So that the reproductive organs are protected and the body shape is more streamlined. But in humans the testes is outside and there is a reason for that. The temperature in the testes should always be 1.1° below the body core temperature to ensure development of functioning sperm. e.g. bottlenose dolphins have a big heat exchanger close to the testes which cooles this organ by cool blood comming from the skin. This is even more important since big muscles used for swimming pass close to the testes and emit additional heat. The length of the whales' penis depends on species. In big baleen whales like blue whales it can be up to 3m long. Back to the top of the page
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Pectoral fins and fluke of the humpback whale
