Constrained by cognitive constraints, humans have had "beautiful misunderstandings" about many kinds of animals. Even whales are no exception, they are uncompromising mammals, but they were once considered a large fish by humans. What many people don't know is that whale ancestors were also amphibians. Without the efforts of paleontologists, this secret would forever be buried in the old paper pile of history.
So why are whales now confined to the water? Their ancestors "lived permanently" after they went into the water, is it because they can't stay on land?
<h1 class="pgc-h-arrow-right" data-track="6" Who were the ancestors of whales >? </h1>
At present, the mainstream view in the biological community is that the ancestors of whales are Pakistani whales (Bucky whales). This animal belongs biologically to mammals , even-hoofed order , cetaceans , and bucky cetaceans , hence the name given to the first discovery in Pakistan.
Judging from the restorations that humans have drawn from the fossil bones of Bucky whales, it is difficult to associate it with whales.
Bucky whale skeleton fossils
Whales are large and can easily reach weights of thousands of kilograms. Not only that, but its shape is closer to the appearance of aquatic animals. Its ears became inaccessible ear holes, and its limbs and tail evolved into pectoral and caudal fins.
Bucky whales may weigh even a fraction of a whale. In addition, bucky whales and whales are also very different in appearance. Bucky whales are closer to small and medium-sized land animals such as wolves, retaining the iconic limbs and ears of terrestrial animals.
Bucky whale restoration
<h1 class="pgc-h-arrow-right" data-track="10" >Why do bucky whales go into the water? </h1>
There are different theories about why Bucky whales decided to become aquatic animals. I personally think that the more reasonable is the predator theory.
Bucky whales, which lived 53 million years ago, already had amphibious capabilities at that time. Although it is also a carnivore, it is subject to the suppression of body size and does not have an advantage in the process of competition with other large carnivores. To survive, they are forced into rivers as well as shallow seas to hunt. Bucky whales that enter the water body are "like fish in the water", because it is less difficult to hunt prey in the water than on land.
Although bucky whales can already live in water, their appearance needs to evolve again. Because bucky whales have ears that are easy to enter water, they need to change their appearance to adapt to the aquatic environment, and although its fur can play a warm role on land, it is an obstacle in the water. In addition, the body structure of the terrestrial mammals of Bucky whales also needs to be greatly modified, otherwise it will be difficult to survive in the ocean.
The problem that plagues Bucky whales the most is the problem of movement. Bucky whales' limbs and tails are extremely convenient to use on land, but they are a huge burden if they are put in the water. The contour of its body is not completely streamlined, which makes it extremely difficult to swim against the resistance of the current.
Bucky whale's body causes it to expend more physical strength than other aquatic animals when it swims for long periods of time, and naturally it is unable to even out other physical strength for predation.
Bucky whales swimming
<h1 class="pgc-h-arrow-right" data-track="20" > how did bucky whales evolve? </h1>
In order to be able to live in the water, Bucky Whale began a painful and long evolutionary process. Archaeologists have confirmed that whales in the true sense of the word appeared 43 million years ago, and these whales are the descendants of Bucky whales that entered the ocean. Although they are not the size of a horse, their appearance has basically changed into the appearance of an aquatic animal.
In order to reduce the loss of energy, the once warm fur becomes a thick subcutaneous fat. The strength of the limbs and tail has increased, and the swimming speed is faster than when it was first launched. And those Bucky whales that were not launched in the water disappeared in the process of changing times.
<h1 class="pgc-h-arrow-right" data-track="24" >Why whales didn't evolve their gills? </h1>
After a long period of evolution, whales have finally fully adapted to the marine environment. Large whales are "dominant" in the ocean, and few other animals dare to provoke them. Whales, however, did not evolve gills endemic to fish.
Many people think that gills are more efficient in water than lungs, but this is actually a stereotype. Whales have naturally accumulated countless survival experiences over tens of millions of years of evolution. If the gills are more efficient than the lungs, they will definitely abandon the lungs and breathe with their cheeks.
Whale internal structure
The efficiency of the gills is actually very low, and the fish need to inhale oxygen and discharge carbon dioxide through water. If the oxygen content of the water body is reduced, it will directly affect the survival of the fish. Whales, on the other hand, can control the contraction of subcutaneous fat and float up to sea level to breathe.
The whale's lungs have also been adjusted to be able to breathe underwater. Most terrestrial mammals have respiratory tracts connected to the nose and mouth, which makes it extremely easy to choke in water. Whales that have completed their evolution use a water spray hole above their heads to breathe, through which they expel carbon dioxide-rich seawater before inhaling oxygen.
Whales have a very strong lung capacity, and the air inhaled in one time can fill 90% of the lungs. In most mammals, the air inhaled at a time can only fill 15% of the lungs. This oxygen that enters the body is stored through the bloodstream and into the myoglobin of the muscle tissue. The amount of dissolved oxygen is extremely large, and the oxygen inhaled at one time can be used for an hour or two, and naturally does not need to surface frequently to breathe.
<h1 class="pgc-h-arrow-right" data-track="30" >why whales have lungs but can't go ashore? </h1>
Whales also use lungs to breathe, but they will die when they go ashore. This is because the whale's body has fully evolved into the appearance of an aquatic animal, and it is difficult to adapt to life on land anymore.
The limbs of whales have become fins over a long course of evolution, and although in the oceans whales rely on them to swim extremely fast, they cannot play a supporting role on land. The whale's body has also undergone structural changes in order to adapt to the water pressure of the ocean. As a result, whales that are accidentally photographed on the coast are difficult to withstand the pressure of the land, and their internal organs and bones are seriously damaged. Many whales that have been accidentally stranded die directly from asphyxia caused by damage to respiratory organs.
In addition to the internal structure, the whale's skin has also been adapted to marine life. The whale's skin is smooth and hairless and needs to be soaked in water for a long time to stay moist. If you stay on a dry, waterless beach for a long time, plus the sun burns for a long time. Whale skin is extremely susceptible to dryness, cracking, and increased body temperature, eventually dying directly from dehydration and heat. Therefore, whales that have accidentally landed ashore are spotted. The first thing people do is to pour water on them to keep their surface moist, rather than help them get back into the ocean.
If you don't know how bad the whales ashore are, think of the hippopotamus that come ashore. Hippos that stay on land for a long time not only have dry and cracked skin, but also become sluggish. At this time, the hippopotamus, when targeted by predators, will not fight back, so it is tragically preyed upon. Hippos and whales are related races, and the "fate" of whale stranding is similar to that of hippos.
Hippopotamus ashore
<h1 class="pgc-h-arrow-right" data-track="36" why are whales stranded so many times >? </h1>
Although whales cannot be disembarked, there have been many incidents of whale strandings. Sadly, even with the help of well-wishers, stranded whale mortality rates remain high.
For whales, stranding is a painful and long way to die. Whales photographed on the beach will gradually die while remaining conscious. This process is accompanied by severe pain from internal organs and bone damage, as well as dehydration due to dryness on the surface of the body. The scary thing is that this process can be as short as hours and as long as days!
The reason why the whales ran aground has also aroused the curiosity of biologists. After a series of studies, they have concluded several reasons:
Topography – This view was held by the Dutch scholar Van Shedddock. He argues that:
Whale strandings may be related to meteorological conditions in coastal terrain. Because they mostly occur on coasts with gentle slopes. When a whale sends an ultrasonic signal here, its echo signal is distorted, making it unable to detect the location of the deep water at all, leading to a loss.
But studies have shown that gentle shores do not cause confusion of echo signals, plus straits and cliffs do not lead to stranding. Therefore, the theory of topography simply does not stand.
Aberration – Some argue that whales may be frightened or have the misfortune to land and run aground while fleeing human harassment. This is not nonsense, as traditional whaling in the Faroe Islands, Denmark, is carried out by driving whales to land and run aground.
Guiding theory – Some whales are social animals and have an older whale as the patriarch of the group. The patriarch was responsible for guiding the whales' activities and predation, and when the patriarch ran ashore under the torment of illness, the whales also made its funerary offerings.
Etiology – Whales may develop lung disease, which causes them to have reduced breathing capacity and extreme weakness. In order to breathe air, they can only float on the surface of the sea for a long time. These sick whales, while breathing, are washed directly onto the beach because they cannot control their physical activity.
Feeding theory – Whales have a habit of nearshore feeding, entering shallow seas to prey on small fish and mollusks that migrate to spawn. Due to gluttony, it was too late to return to the ocean at low tide, and finally washed up on the beach and stranded.
Atavism – The whale's ancestor, bucky whale, was an amphibian whose descendants partially retained terrestrial habits. Although whales cannot return to the mainland, they are still driven by instinct to rush to the beach and run aground.
With the exception of topographical theory, most of them explain well why whales ran aground. Only by truly exploring the cause of whale stranding can we better study the countermeasures to rescue whale stranding and reduce the mortality rate of stranded whales.
After tens of millions of years of painful evolution, whales have adapted optimally to life in the ocean and become the top of the ocean's food chain. However, the seemingly indestructible whale is controlled by its own instincts and is confused and dies.
This is really a lament: the whale's biggest enemy is actually himself!
bibliography
[1] LIU Hui. Why whales run aground[J].Fang Yuan, 2020(21)