For any animal, releasing sperm cells requires a little time and energy. Using too much energy can prevent them from doing the work required to survive, including finding food and water or sleeping. But what are the upper limits for gamete production? of a small fish called medaka (Orysias LatibMales have the ability to mate 19 times a day. Details of the results are provided in A The study was published January 8 in the journal Royal Society Open Science.
How do fish reproduce?
Most fish species mate using… External fertilization. Female will Depositing eggs outside the bodyUsually near the bottom of bodies of water or in a nest built of rocks and other sediments. The male fish then swims over the eggs and releases sperm several times a day. This helps Increase the chances of fertilizing more eggswhich leads to more offspring. Female fish may then collect the fertilized eggs and lay them on plants.
Medaka– also known as the Japanese rice fish – are only about 1.4 inches long and can be found in rice fields, ponds, swamps, quiet streams, and tidal pools in Japan. They are a Popular ornamental fish It has been used by scholars such as: A model for studying the genetic basis of diseases. Understanding the limits of mating can help scientists gain insight into what it takes for a species to survive.
“Medaka are among the spawning fish, where fertilization occurs after eggs and sperm are released into the water. “Due to the difficulty of collecting these gametes, the number of sperm released and the rate of fertilization during successive matings has remained a mystery,” says Yuki Kondo, co-author. in study and evolutionary ecologist at Osaka Metropolitan University in Japan. He said in a statement.
They mate 19 times a day in the laboratory
In this New studyKondo and his colleagues used a previously developed method to measure sperm count in medaka. The day before the experiment, males and females randomly selected from different rearing tanks were placed in separate Plexiglas tanks. The next day, a male and female were placed together in a tank and their behavior was observed until the end of mating or for approximately 20 minutes if mating did not occur. The male is then 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. In addition, eggs were gently removed from the abdomens of females after they had been collected and brought to Petri dishes to evaluate fertilization rates.
[ Related: Whale shark pre-mating ritual observed for the first time. ]
They found it A male medaka can mate an average of 19 times a day. In the first three mating sessions, the medaka released more than 50 percent of its daily sperm production. The fertilization rate was nearly 100 percent in early matings, but this decreased significantly after the tenth time. In some subsequent cases, there was no confirmed fertilization.
Female medaka can Egg production once daily. However, they release all of their eggs when they mate, and many of the eggs will be lost when they mate with males who have already released most of their sperm.
According to the team, these results suggest that there are significant reproductive costs to males and the potential for sexual conflict due to limited sperm availability. However, it does not take this into account Real world conditions encountered by midakas in the wild.
“Our experiments were not intended to mimic natural conditions, but rather to determine the limits of males’ daily mating capacity and the potential reproductive rate of medaka by removing factors that limit their reproductive success, such as limited nutrition and mate availability.” the team wrote in the study.
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