The science news of the week: In a few weeks, the United States is expecting a rare phenomenon – the return of Generation X. Billions of so-called periodical cicadas, which have been waiting for their moment in the pitch black underground for 17 years, will emerge into the light in synchrony. All the while, young cicadas, called nymphs, were feeding on the roots of the trees to undergo their final molt and become fully grown insects. Now they have only a few weeks to manage to sing their song loudly, find a mate, mate, lay eggs, and… do it all again in 17 years.
There are more than 3,000 species of cicadas in the world, most of which appear in a cyclical pattern every two to five years. However, only a small number of adults emerge each year, and only three species of North American cicadas meticulously adhere to a 17-year cycle. Periodic insects are an extremely rare phenomenon, and one of the explanations lies beneath a thick layer of ancient ice. “They extended their life cycle during the ice ages of the last few million years because they simply did not have time to complete their development during the growing season,” explains cicada expert and University of Connecticut professor Chris Simon. The second reason is the surface survival strategy. They simply do not have it. Well, it exists, but it does not depend on the cicadas themselves, because it is the so-called predator saturation effect, when there is so much food that they cannot eat any more. Synchronously emerging from underground, cicadas survive by their sheer numbers. It is interesting to note that not all cicada nymphs develop equally due to differences in feeding conditions, temperature regimes, and other factors, but by the time they reach the age of 17, they all catch up to the same level.
We explain quickly, simply, and clearly what happened, why it matters, and what’s next. The number of offers should remain: episodes. End of story: Podcast Advertising. “And then we come full circle,” says Professor Simon. “If they emerge at a different time, predators will quickly eat them – or they won’t be able to find a mating partner.” Despite a survival strategy perfected over millions of years (and seemingly countless numbers), periodical cicadas remain very vulnerable insects. Generations XI and XXI have practically disappeared, generation VII is in decline. Cicadas need a lot of trees to lay their eggs. In addition, climate warming and the lengthening of the growing season are forcing some cicadas to switch from a 17-year cycle to a 13-year cycle, as has already happened with the M. neotredecim species in the Midwestern United States. Periodic cicadas are an important part of the ecosystem. Nymphs serve as food for animals living underground, adults are eaten by many predators, and even those cicadas that are not eaten provide benefits by ultimately becoming fertilizer for the same trees. “Cicadas are delicate creatures, they do not bite or sting, they are not attracted by people, but by sound,” says Professor Simon, inviting everyone who is not afraid of noise and thousands of swarming insects to take a closer look at this seventh wonder of the world with the mobile application Cicada Safari.
It is said that tears cannot help with grief, but they are very useful for the eyes, so a malfunction of the tear glands can have serious consequences, up to blindness. The tear glands, located above the eyeball, perform an important function – they moisturize the eyes, and if their work is disrupted, the eye can become dry or, on the contrary, constantly watery. Some of these injuries can be treated with eye drops and sometimes surgery, but scientists acknowledge that there is currently no truly effective treatment because the tear glands are poorly understood. What molecular geneticists led by Hans Clevers of the Hubrecht Institute in the Netherlands have achieved is therefore a real breakthrough. First, they grew miniature, three-dimensional replicas of human tear glands from stem cells in a test tube, and these organoids demonstrated the structure and functions of a fully functioning gland: in the presence of the neurotransmitter norepinephrine, they swelled and produced tears. The scientists then decided to test the suitability of such organelles for transplantation. They transplanted human lacrimal gland cells into the lacrimal glands of mice. Within two weeks, the cells were able to colonize and begin to form their own structures. And even after two months, the cells continued to grow and divide – even producing tear protein. Of course, growing fully functional artificial tear glands and transplanting them into humans is still a long way off, but the results of a new study convince scientists that the first step in the right direction has been taken.
When the whaling industry began to make significant profits in the late 18th century, the number of whales killed reached hundreds of thousands. At that time, no one thought that whales were magnificent animals with high intelligence that needed to be studied and protected. Soon the whalers conquered both the Pacific and the Arctic Oceans, and by the 19th century whales were still being hunted. At some point, however, the logs of American whaling ships, which recorded the number of whales sighted and harpooned, began to show that hunting had become more difficult and that the number of successful hunts had dropped by more than half. As Scottish researchers studying sperm whales have found, the whales were able to understand that they were being targeted and began not only to avoid encounters with whalers themselves, but also to teach the younger generation to do the same. “We concluded that individual, inexperienced whales learned defensive measures from groups of whales that had already acquired and tested such experience in practice,” write the study’s authors. “The confrontation with the whalers could last for hours, and the sperm whales were able to hear each other and coordinate their actions over distances of several kilometers thanks to echolocation.” According to the leader of the research group, Dr. Luke Rendell of the University of St. Andrews in Scotland, the whalers themselves detailed and described the protection methods invented by the sperm whales. It turns out that these resourceful mammals have learned to exchange messages of danger within their groups, to elude whalers by swimming against the wind (a must in the era of sailing ships), and even to attack whaling ships. Scientists say that if whales were able to change their behavior to avoid human threats 200 years ago, there is nothing stopping them from doing so now, even though the level and volume of those threats have increased significantly.