They have survived the ice age to the present, survived the cold, survived the desert drought, and have lived in extreme environments for tens of thousands of years, but their number is getting smaller and smaller.
The medaka was discovered in 1928, when only 500 fish remained were crammed into a deep-water hole in the Mojave Desert. By 2006, their number had dropped to a pitiful 38, and it had only been 78 years.
(Devil's Cave, the habitat of the medaka fish)
<h1 class="pgc-h-arrow-right" data-track="5" > "evolutionary miracle" medaka</h1>
Medaka fish congregate in a subterranean aquifer ,Devil's Hole in Death Valley National Park, Nevada, USA. During the Ice Age, Death Valley was originally a vast ocean, after the earth underwent great changes, the ocean became a desert, leaving only a waterhole in the lowest and deepest part of the desert, the water surface is about 18 meters away from the desert ground, although the water has not been evaporated, but there is no water source around the pool, it is a pool of stagnant water, and the amount of water is maintained by a small amount of rainfall in the desert every year. The water temperature of this waterhole is maintained at about 33 ° C all year round, and the oxygen content is very low, and the salt content is four times that of ordinary seawater.
(Medaka)
It was in this case that the medaka, which was less than 3 centimeters long, survived here for nearly 60,000 years and survived a magnitude 7.1 earthquake. If you can survive in this desperate situation, why is the medaka still on the verge of extinction?
<h1 class="pgc-h-arrow-right" data-track="5" > conjecture about the cause of the endangerment</h1>
The number has plummeted for unknown reasons
Paul Barrett, a staff member of the American Fish and Wildlife Conservation Association, said that the sharp decline in the number of medaka may be a genetic problem that makes it difficult to reproduce, but the specific reason is still unknown, leaving them helpless.
The water level decreases
The United States has developed agriculture tens of kilometers away from the Devil's Cave, pumping a large amount of groundwater from the waterhole, and after the water level has dropped, it has also revealed the spawning ground of the medaka, inhibiting the reproduction of the medaka.
(Water level measuring instruments are set up all year round)
Food is scarce
The medaka feeds on algae in the water, and the growth of algae requires sunlight, but due to the lower water level, the sun cannot shine in the water, the algae plants are less and less, and the medaka lacks food and is more difficult to grow and reproduce.
Easy to mutate
Biologists have brought them back to the lab to study, and they have found that the fish is actually very adaptable, like a chameleon, able to change its traits according to external conditions. For example, in water with high oxygen content, the color will be more vivid, the food will become larger, and it will also cross with other fish to form a new variety of fish.
Not valued
American scientists realized that to protect this small fish, they could only protect their habitat first. In 1976, the medaka was listed under the Endangered Species Protection Act, and the U.S. Supreme Court required the minimum water level in devil's holes to be retained and prohibited groundwater extraction. But the little medaka may be too inconspicuous, unlike pandas, vultures, and other eye-catching big guys, who have not been taken seriously.
In 2016, three drunks also drove into the Medaka Sanctuary, swimming in the devil's cave, and not only that, but also left vomit in the waterhole. Although the three drunks were finally punished as they deserved, they came during the breeding season of the medaka, and it is not known how many eggs they destroyed.
<h1 class="pgc-h-arrow-right" data-track="5" > other efforts to protect them</h1>
When watching a species come to an extinction, scientists certainly don't sit idly by. In order to expand the fish population, three new waterholes such as water quality and water temperature were built nearby, and some of the medaka were put in, but after 5 years they found that there were no medaka in the new habitat. This habitat cannot be completely replicated, but a slight difference can cause medaka to mutate into other species.
In the decades since the establishment of the reserve, the number of medaka has not increased significantly. Biologists at Death Valley Park remain convinced that they are important and keep experimenting with artificial breeding. By the end of 2019, it had successfully recovered to 187 articles. But the crisis has always existed, and even if more than 100 have been successfully bred, the decrease in their number is without warning, and it is possible that in two years it will decrease sharply.
But this result has to make people suspicious. The medaka is heading for extinction, should humans intervene?
<h1 class="pgc-h-arrow-right" data-track="5" > whether to continue to protect the medaka</h1>
That view of protection
The latest research shows that human activities on Earth have seriously affected the living environment of animals, causing hundreds of wild animals to be endangered. There are 500 species of mammals, birds, amphibians, and reptiles in danger.
Some scientists believe that the current extinction crisis is inextricably linked to pollution and climate change, and that humans, as the culprits of all this, have a moral responsibility to protect them or remind others to protect them.
Let it go to extinction views
But some argue that humans didn't deal a fatal blow to the medaka, and they have no predators in their habitats. The extinction of the medaka may be the result of natural selection, a species eliminated by natural selection, and is it a violation of the laws of nature that humans are trying to protect?
And because humans are so fond of exploring that they can't wait to study a new species when they discover it, does that disturb their normal activities? Whether it's taking them out for study or recreating habitats for them, the effects are counterproductive, and whether human interference causes organisms to reverse evolution and become less and less adaptable to the environment.
Others wonder if they can adapt to the changes since they can survive outside and hybridize with other fish. It may be wrong to focus only on avoiding species extinction while ignoring the evolution and emergence of new species. Perhaps the way the medaka adapted to the current Earth was by interbreeding with other fish to become a new species.
However, a species that goes extinct may not have any direct impact on us. But protecting this humble little animal is also to make us less numb to the extinction of species, otherwise hundreds of species will become endangered in the future, and we will all sit idly by, and in the end, we may still hurt humans. Do you think you should continue to study the protection of the medaka, or let it develop until it becomes extinct?