For any animal, releasing sperm cells requires a bit of time and energy. Using up so much energy can keep them from the other required work of survival, including finding food and water or sleeping. But just what are the upper limits of gamete production? For a tiny fish called the medaka (Oryzias latipes), males have a mating capacity of 19 times per day. The findings are detailed in a study published January 8 in the journal Royal Society Open Science.How do fish reproduce?Most fish species mate using external fertilization. The female will deposit eggs outside of the body, usually near the bottom of a body of water or in a nest built out of rocks and other sediment. The male fish will then swim over the eggs and release sperm several times per day. This helps increase the chances that more eggs will be fertilized, leading to more offspring. Female fish may then collect the fertilized eggs and deposit them on plants.Medakaaka the Japanese rice fishare only about 1.4 inches long and can be found in rice paddies, ponds, marshes, quiet streams, and tide pools in Japan. They are a popular aquarium fish and scientists have used them as a model to study the genetic basis of diseases. Understanding the limits of mating can help scientists gain insights into what it takes for aspecies to survive.Mekeda are a popular aquarium fish. CREDIT: Osaka Metropolitan University Medaka are among the fish that spawn, where fertilization occurs after the eggs and sperm are released in water. As these gametes are difficult to collect, the number of sperm released and the fertilization rate during successive matings had remained a mystery, Yuki Kondo, a study co-author and an evolutionary ecologist at Osaka Metropolitan University in Japan, said in a statement.Mating 19 times per dayin a labIn this new study, Kondo and colleagues used a previously developed method to measure the sperm count of medaka. The day before the experiment, randomly selected males and females from different breeding tanks were put into separate glass tanks. The next day, a male and a female were put into a tank together and their behavior was observed until the end of mating or for about 20 minutes if mating did not occur. Then, the male was removed from the tank and placed in another tank with a new female. The team repeated this process until the male failed to mate with the three females in a row. Additionally, the eggs were gently removed from the females abdomens after they scooped them back up and brought them into Petri dishes to assess fertilization rates.[ Related: Whale shark pre-mating ritual observed for the first time. ]They found that male medaka can mate 19 times per day on average. In the first three mating sessions, the medaka released over 50 percent of their daily sperm output. The fertilization rate was nearly 100 percent in the early matings, but this significantly decreased after the 10th time. In some later cases, there was no confirmed fertilization.Female medaka can produce eggs once per day. However, they release all of their eggs when mating and many of the eggs will go to waste when and if they mate with males who have already released most of all of their sperm.According to the team, these results suggest that there are substantial reproductive costs for males and a potential for sexual conflict due limited sperm availability. However, it does not take into consideration the real world conditions faced by medakas in the wild.Our experiments were not intended to mimic natural conditions, but rather to identify the limits of males daily mating capacity and the potential reproductive rate of medaka by experimentally removing factors that limit their reproductive success, such as limited nutrition and mate availability, the team wrote in the study.The post These fish can mate 19 times per day appeared first on Popular Science.

Skip to contentNewsAnimalsPoop is on the menu for a surprising number of animalsA new tally finds dozens of species willing to give food a second go-round Perfectly normal animals at times eat poop. A baby koala (top left) starting its life of eating chemically defended leaves may pick up helpful gut microbes from moms droppings. Other vertebrates routinely glean left-behind nutrients from other species at sea (parrotfish, top right) or on land (pika, bottom left). The time crunch of early parenthood drives unusual snacking among Eurasian jays (bottom right) and other guardians minimizing departures from nests.From top left, clockwise: JeannetteKatzir/iStock/Getty Images Plus; Mike Goodwin/500px/Getty Images Plus; Federica Grassi/Moment/Getty Images Plus; George D. Lepp/Corbis Documentary/Getty Images PlusBy Susan Milius59 seconds agoFeces dont get enough credit as food.The stinky stuff is not just an end product after food gets eaten, digested and finally discarded by animal guts. Poop can also be something nutritious, useful and actually eaten (again) in its own right, three researchers point out in the December issue of Animal Behaviour. Tallying just the examples from vertebrates reported in scientific journals, the authors document coprophagy in more than 150 species, from adult black bears to baby koalas.

Nature, Published online: 08 January 2025; doi:10.1038/d41586-024-04176-6A good day.

Nature, Published online: 08 January 2025; doi:10.1038/d41586-024-04217-0It began with concerns about the orbits used to explain the motion of electrons in atoms but quantum theory ended up upending reality itself.

Nature, Published online: 07 January 2025; doi:10.1038/d41586-025-00028-zWe examine evidence that global warming might be speeding up and ask what happened to the egalitarian CucuteniTrypillia culture.

Hemsworth, a colossal funnel-web spider recently donated to the Australian Reptile Park, could make significant contributions to the park's life-saving venom-milking program, keepers say.

Trichuris incognita is a newfound intestinal roundworm closely related to the whipworm parasite. However, it is significantly more resistant to treatment.

Next month, Capcom will bring Monster Hunter Wilds to players just over seven years since the last mainline game, Monster Hunter: World, debuted in 2018. There was an open beta for players in October, and now Capcom has announced that a second open beta in February. The news was accompanied by the following video, which features Monster Hunter Wilds producer Ryozo Tsujimoto using the create-a-character function to place himself in the game. In terms of content, the new beta will be very similar to the one from last year. Players will still be able to use the character creator, try out the story trial, and complete the Slay Doshaguma quest. However, this version of the demo will also include Gypceros, a monster from the previous games who was absent in the first demo.According to Tsujimoto, characters created in the first beta can be carried over to the second beta and to the final version of the game as well. However, game progress will not be transferable. The second open beta will be held over two weekends on Xbox Series X|S, PlayStation 5, and PC. It will also be cross-platform, and the beta is open to all players regardless of whether they have Game Pass or PlayStation Plus.Continue Reading at GameSpot

A Shadow of the Colossus movie has been in the works for more than a decade already, and despite nothing materializing yet, the project's director has issued a hopeful statement about it. In a recent interview, Andy Muschietti said Shadow of the Colossus is a "masterpiece" and that he's played it several times. Now, after 10 years, the "possibility of making [the movie] is opening up," he said.Muschietti told La Baulera del Coso on Radio TU that he's been impressed by the script he's seen, but whether or not he'll actually get to make the movie may come down to financing."Shadow of the Colossus is a cult game, but to make a good film, there is a studio that puts the numbers and says how much it is worth to give the director $200 million, $150 million, or $100 million," he said (via Eurogamer). "There are different versions of the film, and obviously, I want them to give me $200 million, but this is another factor to take into account."Continue Reading at GameSpot

In the absence of any official news about the Switch 2, rumors and reports about it are popping up all over the place, including at the Consumer Electronics Show this week in Las Vegas. The latest rumor stems from peripheral company Genki, which is showing off accessories for the Switch 2 at CES and even reportedly telling one journalist that the system will launch in April.Accessory manufacturers like Genki might get advance notice of upcoming hardware announcements, but there is no indication here that it's the case. Genki is also displaying what it claims to be a genuine replica of the Switch 2. The company apparently created a mock-up of the Switch 2 as a stand-in to show how Genki's accessories, including a docking station and case, will work for it.The report from Numerama (via VGC) also states that the Switch 2's new Joy-Cons have an optical sensor and a "C" button, the purpose of which is unknown. Again, all of this information should be taken with a grain of salt.Continue Reading at GameSpot