Whales live in the ocean and swims on its fins, but instead of breathing with gills like fish, it breathes with lungs like other mammals. There is a big difference between breathing with lungs and breathing with gills. When fish use their gills to breathe, they can breathe directly in the water, but whales cannot be in the water when they breathe with their lungs. Because the oxygen content in the water cannot meet their requirements, they need to go to the surface to breathe. Whales have a very large amount of exercise and consume more energy, but they can remain unbreathing for a long time after one breath. This is very different from the different breathing conditions of humans and most other animals.
In mammals, there are two important proteins related to oxygen, which are hemoglobin and myoglobin. According to an article "How do whales breathe?" from Whale & Dolphin Conservation USA, it said that "Whales have twice the amount of hemoglobin in their blood then we do. So while your blood is 30% hemoglobin, a whale’s blood is 60% hemoglobin – allowing them to store twice as much oxygen for long dives. In addition to more hemoglobin, whales’ bodies have a higher percentage of blood – allowing even more oxygen storage. Blood takes up 10-20% of a whale’s body volume, while our blood volume to body ratio is only around 7%.We also store oxygen directly in our muscle tissue in a protein called myoglobin. Whales’ myoglobin concentrations in their muscle are up to 30% higher than their terrestrial relatives. This molecule is distributed throughout the muscles in the body and holds up to 35% of whales’ oxygen stores. This is crucial as it’s important for oxygen to not only last as long as possible, but also be constantly supplied to the brain while they are under water. "[1]
The whale has a blowhole on its head. When the oxygen stored in the whales is exhausted, they will rise to the surface of the water again for the usual gas exchange. At this time, the whales will produce a mist of water when they exhale.
How do Whales Eat
There are many types of whales, and different types of whales consume different types of food in the ocean.
According to an article "What Do Whales Eat?" from Harbor Breeze Cruises, it mentioned that "The type of whale food a whale eats is largely determined by whether they have teeth or not.
Baleen Whales: Unlike toothed whales, baleen whales (humpbacks, minkes, and right whales) do not have teeth. Instead, they possess bristles, much like the bristles of a comb, that act as a net to capture prey. Baleen whales are known to engage in filter feeding, a unique method of hunting, which involves grazing the surface of the ocean to capture tiny morsels of whale food.
Toothed Whales: Toothed whales (sperm whales, white whales, beaked whales) use a very specific hunting method to catch their prey: Echolocation. Echolocation occurs when the whale emits a collection of busing and clicking noises. The whale will then listen to the echoes of the sounds made that bounce off of nearby objects. The length of time required for the echo to return to the whale indicates the distance of whale food, the density of the whale food, and even if the whale food is moving or sitting still. "[2]
Baleen whales mainly eat shrimp and small fish. When they swim in the ocean, they open their mouths and suck many small fishes and shrimps into their mouths together with the sea water, and then close their mouths to filter out the sea water. So small fish and shrimps were swallowed into their stomachs. One meal can eat more than two thousand kilograms. Toothed whales mainly eat larger creatures, such as penguins and seals. When they encounter food, they pounce on it fiercely, bite with sharp teeth, and eat it quickly. They are like "tigers in the sea".
How Do Whales Communicate
Communication in the water is also a challenge for whales. Taste is useless, vision is limited, and touch requires a little skill.
According to the information form NOAA's National Ocean Service, it mentioned that "Whales are very social creatures that travel in groups called “pods.” They use a variety of noises to communicate and socialize with each other. The three main types of sounds made by whales are clicks, whistles, and pulsed calls.
Clicks are believed to be for navigation and identifying physical surroundings. Clicks can even help to differentiate between friendly creatures and predators. Clicks have also been observed during social interactions, suggesting they may also have a communicative function. Whistles and pulsed calls are used during social activities. Pulsed calls are more frequent and sound like squeaks, screams, and squawks to the human ear. Whales also use their tails and fins to make loud slapping noises on the surface of the water to communicate nonverbally. "[3]
The most surprising thing is that whales do not need to exhale air to make a sound. Water is an excellent transmission medium for sound. Whales can rely on sound to "see" the ocean and receive information from the ocean.
How Do Whales Sleep
As higher animals living in the sea, whales need to sleep just like humans. We know that although whales live in water, they still breathe with their lungs. So how do whales sleep?
According to an article "Do Whales Sleep?" by Katie T. from Whales of Iceland, she said that "Luckily whales and dolphins are well adapted to their lives underwater. While all whales sleep, it seems that different species have different sleeping requirements and methods. The amount of sleep and the way that they sleep can vary greatly between species – and since it is quite difficult to study their sleep in the wild, varying information has been reported. There are a few more common sleeping positions: resting quietly in the water (horizontally or vertically), sleeping while swimming slowly next to another animal or in a group, or floating on the surface (often called logging). Dolphins in captivity have also been recorded sleeping for short periods of time at the bottom of their tanks. Humpback whales seem to be most often found resting motionless on the surface for increments of up to 30 minutes. They cannot sleep much longer than this without losing too much of their body temperature when inactive."[4]
Therefore, for whales, when they sleep, it is like a human being holding their breath. When whales are sleeping, they will float in the water without breathing at all. We know that the lung capacity of whales is very large, and there is no problem for whales without breathing for more than 20 minutes. After they finish this nap, they will wake up and float on the surface of water to breathe.
How do Whales Excrete
Whales are the largest mammals in the ocean. They eat a lot each time, so the amount of their excretion should also be very large. The digestive system of whales is similar to the consumption system of terrestrial mammals. After whales swallow food, the food reaches their stomach, and then the food reaches the intestines. The nutrients in food are absorbed into the blood. The remaining waste is discharged into the ocean through the anus.
According to the article "Whale Poo: The Ocean's Miracle Grow" by Wynne Parry from Live Science, it said that "While many mammals produce excrement in clumps, whale poop is more of a slurry. Whale poop doesn't sink to the bottom of the ocean. Rather the fluffy plume floats at the surface."[5]
Also, according to the research of whale biologist, Joe Roman from University of Vermont, these large amounts of excrement provide the ecosystem with higher nitrogen. And since most of the whale's excrement is liquid, these nutrients will stay on the surface of the ocean instead of sinking. This will greatly enhance the quality of life of phytoplankton. At the same time, it also has a great help in regulating the marine ecosystem.[6]
Whale excrement is not only important for the ecosystem, but also as a spice. Ambergris is a famous and important spice ingredient, and its formation is also related to sperm whale excretion.
Pressure Tolerance
The ancestors of whales lived on land, but whales have lived in the ocean for tens of thousands of years. After long-term evolution, whales have adapted to this harsh environment, and their organs, tissues and certain functions have also undergone tremendous changes.
According to the article "How do deep-diving sea creatures withstand huge pressure changes?" from Scientific American, it stated that "Diving to depth can result in mechanical distortion and tissue compression, especially in gas-filled spaces in the body. Such spaces include the middle ear cavity, air sinuses in the head, and the lungs." [7]
When a whale dives deep, the lungs will receive a lot of pressure, the alveoli will be compressed, and the remaining air pressure will enter the large trachea. When the exchange surface of the alveoli is completely compressed, the whale’s lungs will exchange little or no gas. One of the reason why whale can dives deep is that they have a very high levels of hemoglobin and myoglobin, which could help them store O2 in the blood and muscles. In addition, the long-term underwater life makes the whale's epidermis become a very thin film, which can fill the whale's physiological tissue with water, maintain sufficient resistance to pressure, and maintain the balance of internal and external pressure.[8]
Freeze Tolerance
Whales are endothermic, or warm-blooded mammals. Endothermic animals refer to animals that can regulate their own body temperature in zoology. Their mobility is not dependent on the outside temperature like the temperature-changing animals. In birds and mammals, a stable body temperature is generated through metabolism. This is reflected in the basal metabolic rate.
According to Whale Forever, it is listed some possibilities for maintaining the body temperature of whales. "The following methods are used to regulate and maintain a healthy body temperature in whales:
Blubber
Blubber is a thick layer of fatty tissue that lies just beneath the surface of the skin. This acts as very effective insulation for the whale, even when it is in the icy waters of the Arctic Ocean. In addition, this blubber provides energy when food sources are scarce, which keeps the metabolism strong and the metabolic functions efficient. This is all vital to ensuring that the animal’s core temperature does not begin to plummet.
Vascular System
By means of an ingenious network of veins and arteries, the blood of the whales is kept warm. This is achieved by a counter-current heat exchange system, which means that blood that is returning to the heart from the extremities (and is cold as a result) runs right next to warm blood that is leaving the heart and going towards the extremities. Heat from the warm blood flows from the arteries to the veins (carrying the cold blood) and heats it up.
Body Shape
The fusiform body shape of cetaceans is another mechanism that aids in the regulation of their core body temperature. Their surface area is kept to a minimum (by not having complex limbs, etc...). This decreases the amount of total area that is exposed to the cold waters."[9]
Limbs Adaptation
We all know that most land animals originated in the ocean. However, some marine animals originated on land, the most famous example is whales. Whales are mammals in the ocean, but few people know that the ancestors of whales lived on land. They once had 4 legs. The ancient ancestors of whales were also animals that lived on land. They crawled on all fours like crocodiles. After that, they gradually started a half-terrestrial and half-aquatic amphibious lifestyle. With the change of survival mode, the body shape of whale ancestors gradually changed to adapt to life in the water. The original limbs evolved into fins, and the shape of the tail became very similar to that of fish.
According to Charles Q. Choi's article "Early Whales Had Legs" in Live Science, he mentions that "The ancestors of whales once strode on land on four legs, just as other mammals do. Over time, as they evolved to dwell in water, their front legs became flippers while they lost their back legs and hips, although modern whales all still retain traces of pelvises, and occasionally throwbacks are born with vestiges of hind limbs."[10]
Why did the ancestors of whales abandon land and turn to marine life? Some scientists speculate that the ocean is rich in food, and there are few ferocious beasts, making it more suitable for relatively mild large animals to survive. This may be the main reason why whale ancestors chose the ocean.
Pavid, K. (n.d.). Secrets of the deepest diving whales. Retrieved December 18, 2020, from https://www.nhm.ac.uk/discover/secrets-of-deep-diving-whales.html
