There is a devil's hole in the Mojave Desert in Nevada, USA, where one of the world's rarest fishes lives- the medaka, which sounds like a terrible fish, but it is actually just a very special small fish, and there is nothing terrible about it from the appearance.
But according to biologists, they have been living in this high-temperature, oxygen-deficient, food-deficient environment since 50,000 years ago, which is simply a miracle, why they can survive for so long, which has aroused the curiosity of biologists.
<h1 class="title__title__e436dd806a uc-nf-fontsize-change-dom" > the tortuous and helpless evolution of the medaka</h1>
The medaka is a kind of desert fish, due to its living conditions, it is now only found in the devil's cave in the "Death Valley" national park in Mojavesha, and was not discovered until 1930, and its body length is only about 2.5 cm, which is about the same size as the newly hatched small trash fish in the creek, which is very inconspicuous. But it is the only species of ray-finned carp in the suborder Carpenteridae, and all the medaka in the world are in this devil's hole, up from 38 in 2016.
The living environment of the medaka
The Devil's Cave where the medaka live is in very harsh conditions, "Death Valley" is the lowest, hottest and driest area in North America, fortunately the Devil's Cave is very deep, and the water surface at the bottom of the cave is 15 meters away from the mouth, so the cave preserves the last trace of shade in the Mojave Desert. But even so, the water temperature at the bottom of the cave remains at about 32 ° C all year round, which is almost the temperature limit for most fish survival, and because of seasonal reasons, the sun is moving south, and the bottom of the devil's cave cannot be directly exposed to sunlight for at least two months.
This means that the oxygen content of the water where the medaka is located is extremely low, because there is no water replenishment in this closed water body, only the water source that seeps in, and on the day when there is no sunlight, the photosynthesis efficiency of algae in the water is very low, and the medaka lives in this clear, but the conditions are extremely harsh in the water desert, this day is imaginable!
The evolution of the medaka
Devil's Cave has been formed for more than 500,000 years, but the medaka came to this cave 50,000 years ago, near the end of the last ice age, and the 50,000 years of isolation are enough for a species to evolve subspecies, and the medaka belongs to a species of desert fish, this fish is very adaptable, especially its growth after hatching is very susceptible to environmental influences, this flexibility is called phenotypic plasticity, which leads to the diversity of desert fish. According to biologists in a simulated environment, it only takes 5 years for the medaka to differentiate slightly in appearance.
This super plasticity allows the medaka to independently evolve skills to cope with the harsh environment in this hole, and high temperatures, lack of oxygen, and lack of food cannot affect their survival, so in 50,000 years, no matter how the outside world changes, the desert fish tenaciously survives.
<h1 class="title__title__e436dd806a uc-nf-fontsize-change-dom" > the biggest crisis in the history of the medaka's survival, comparable to the "extinction of the dinosaurs"</h1>
The medaka has suffered two crises in its history, the first being that increased human activities led to a sharp increase in irrigation water for local agriculture and animal husbandry, which led to a decline in groundwater sources in Devil's Cave, and the water temperature also began to rise after the amount of water decreased. In the spring of 1995, there were more than 300-500 medaka, but by 2013 there were only 35 left! And in this moment of life and death, the medaka is threatened by an asteroid impact that is no less than the extinction of the dinosaurs.
In April 2016, three visitors (Edgar Reyes and Steven Schwenkendorf of North Las Vegas and Trenton Sargent of Indian Springs) broke into the Devil's Cave after drunkenly breaking into the Devil's Cave and swimming naked and vomiting in the only water inhabited by the medaka, which coincided with the breeding period of the medaka, and after being destroyed by these three drunks, a large number of fish eggs died, and the medaka reached a dangerous moment of imminent extinction.
Finally, after environmental protection organizations worked hard to improve the living environment of the medaka, it finally recovered to 187 in 2018, finally making everyone breathe a sigh of relief!
Devil's Hole video during the earthquake
On July 5, 2019, Death Valley National Park was affected by a 7.1-magnitude earthquake near Trona, California, which set off large waves in the waters at the bottom of Devil's Cave, but in the morning the crew found that there were no stranded medaka on the shore, and the medaka escaped again.
But the medaka is still on the brink of extinction!
Since the Cambrian explosion of life, the earth life experienced 5 mass extinctions, many friends think that 65 million years later there will be no major events, in fact, it is not at all, the latest life mass extinction is after the emergence of human beings, from the beginning of human expansion on the earth, accompanied by the extinction of this species, and since the Industrial Revolution, this extinction rate may be visible to the naked eye at an increase.
I hope that there will be no lonely human beings left on the road to future development!